The influence of annealing on the Sb layer in the synthesis of [001]-oriented Sb2Se3 film for photoelectrochemical hydrogen gas generation

RESEARCH ARTICLE www.afm-journal.de The Influence of Annealing on the Sb Layer in the Synthesis of [001]-Oriented Sb2Se3Film for Photoelectrochemical Hydrogen Gas Generation Magno B. Costa, Moisés A. de Araújo, Joaquim Puigdollers, Pablo Ortega, Teresa Andreu, Cristobal Voz, Edgardo Saucedo,* and Lucia H. Mascaro* This work reports a new thermal treatment approach to obtain [001]-oriented Sb2Se3film, which consists of preliminary annealing of the Sb layer before its selenization. Among the different Sb annealing temperatures assessed, the one at 200 °C followed by selenization (Sb2Se3(Sb-A200)) results in a considerably high texture coefficient at the [001] direction, whereas the Sb2Se3film obtained only by selenization of the non-annealed Sb film (Sb2Se3(Sb-NA)) features preferential orientation at the [hk0] direction. In terms of photoelectrochemical (PEC) performance for H2generation, the Sb2Se3(Sb-A200)/CdS/TiO2/Pt film delivers a substantial photocurrent density of −5.65 mA cm−2at 0 VRHE, which is 10 times higher compared to the Sb2Se3(Sb-NA)/CdS/TiO2/Pt film. Additionally, the employment of the Sb annealing step results in stable PEC performance of the Sb2Se3film over 7000 s, meaning that the photocorrosion is minimized. The improved PEC performance of the Sb2Se3film is attributed to better crystallinity and composition closer to the stoichiometric condition, as well as the preferential orientation at the [001] direction that favors charger carriers’ transportation. At last, the findings of this work feature an innovative thermal treatment approach to obtain [001]-oriented Sb2Se3film to further improve H2generation from PEC water splitting. 1. Introduction The concern of depletion of energy resources based on fossil fuels has led lately to a considerable increase in the search for M. B. Costa, L. H. Mascaro Departamento de Química Universidade Federal de São Carlos (UFSCar) Rodovia Washington Luiz, km 235, São Carlos, São Paulo 3565-905, Brazil E-mail: [email protected] M.A.deAraújo InstitutodeQuímicadeSãoCarlos UniversidadedeSãoPaulo(USP) AvenidaTrabalhadorSancarlense,400,SãoCarlos,SãoPaulo13566-590, Brazil The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.202506401 © 2025 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. DOI: 10.1002/adfm.202506401 renewable energy sources that can potentially replace them. More worrying is that fossil fuel resources contribute about 90% of global energy consumption, which impacts the increase in the emission of carbon dioxide (CO2) into the atmosphere.[1]Although CO2is an essential gas for the maintenance of life, the ever-growing release of this gas into the atmosphere, from fossil fuel combustion, can considerably contribute to the intensification of the greenhouse effect and climate changes, and these can cause an increase in the average temperature of the planet and affect the entire existing ecosystem.[2]To circumvent these problems, sunlight has become one of the most promising alternative energy resources due to being abundant and environmentally friendly, ease of usage/harvest, less overall cost, and versatile.[3,4]Additionally, solar energy can be converted to thermal energy via solar water heaters, or electrical and chemical energy via photovoltaic and PEC devices, respectively.[5]Theconversionofsolar energy into chemical energy consists of storing energy in the bonds of hydrogen gas (H2) molecules, and this molecule is known as a dense energy carrier. H2has heat capacity and energy density much higher than batteries,[6,7]and the energy yield J. Puigdollers, P. Ortega, C. Voz, E. Saucedo Electronic Engineering Department Universitat Politècnica de Catalunya (UPC) Micro and Nano Technologies Group (MNT) Jordi Girona 31, Barcelona 08034, Spain E-mail: [email protected] M.B.Costa,J.Puigdollers,E.Saucedo BarcelonaCenterforMultiscaleScience&Engineering UniversitatPolitècnicadeCatalunya(UPC) AvEduardMaristany10-14,Barcelona08019,Spain T.Andreu DepartamentdeCiènciadelsMaterialsiQuímicaFísica UniversitatdeBarcelona(UB) MartíiFranquès,1,Barcelona08028,Spain Adv. Funct. Mater. 2025, 2506401 2506401 (1 of 16) © 2025 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH www.advancedsciencenews.com www.afm-journal.de of H2is 2.75 times higher compared to that of hydrocarbon fuels.[8]One way to obtain H2is via solar water splitting, which can be carried out in PEC cells or photovoltaic panels coupled to electrolyzers.[7] To drive solar water splitting into PEC cells, a variety of semiconductor materials have been under investigation, and among those antimony(III) selenide (Sb2Se3) thin film has stood out as a promising photocathode owing to its adequate intrinsic optoelectronic properties, earth-abundant elements, and low toxicity.[9,10] To exemplify the optoelectronic properties of Sb2Se3, this material has a high absorption coefficient, a, in the ultraviolet and the visible region of the solar spectrum (a>105cm−1),[11]suitable optical bandgap energy, Eg, of 1.1–1.3 eV,[12–14]high mobility (≈10 cm2V−1s−1for minority carriers),[15]long carrier lifetime (≈60 ns),[15]and appropriate energy band position to drive hydrogen evolution reaction (HER) under illumination.[14,16,17] In addition, Sb2Se3has a single orthorhombic crystalline phase composed of quasi-1D (Q1D) parallel ribbons of (Sb4Se6)nin one spatial direction.[18,19]These Q1D (Sb4Se6)nribbons present covalent Sb−Se bonds along the [001] direction, and the ribbons are stacked along the [100] and [010] directions, which are held together by van der Waals forces.[20]The different orientation growth of the (Sb4Se6)nribbons enables the existence of anisotropic crystallographic behavior, meaning that any preferred orientation in the [001] direction (ribbons vertically oriented to the substrate) favors the charge transport, as the charge carriers travel more easily along the ribbon-like structure. On the other hand, the (Sb4Se6)nribbons featuring [100] and [010] directions (ribbons horizontally oriented to the substrate) result in difficulty for charge carriers transport due to the hopping mechanism, that is, charge carriers must hop from one (Sb4Se6)nribbon to another.[20]Such an anisotropic charge carriers’ transportation suggests that a properly textured Sb2Se3film (i.e., featuring [hk1] direction) is the ideal condition for solar energy conversion applications.[20–22]Additionally, the combination of all these properties makes Sb2Se3a very promising semiconductor material to be used as a photocathode for PEC cells when compared to other semiconductors.[23–25] Although Sb2Se3has been extensively demonstrated to be an excellent alternative as a photocathode for solar-driven water splitting,[26,27]the electron-hole recombination process in bulk, and the presence of interfacial defects are recurrent issues[18] that limit to reach satisfactory PEC performance of this material for commercial application.[28]To overcome these issues, the improvement of crystallinity and the control of elemental composition of Sb2Se3have been attributed as the main factors to enhance the PEC performance of Sb2Se3photocathode.[29,30]Regarding, particularly the elemental composition effect, Caño et al.[31]have recently shown that nonstoichiometric Mo/Sb2Se3film gives rise to secondary phases, that is, Se-rich Mo/Sb2Se3film leads to the formation of MoSe2and Se phases, whereas the Sb-rich condition favors the occurrence of Sb2O3and m-Sb phases. In another recent study, Lian et al.[32]identified the presence of deep-level defects in Sb-rich Sb2Se3film, which, based on experimental results, were characterized as amphoteric SbSe defects. Moreover, according to the authors, the amphoteric defects in this material can trap both electrons and holes, resulting eventually in a recombination process. It was also shown that Se-rich Sb2Se3films have relatively less defect concentration as well as a reduced number of shallow energy levels. Besides the elemental composition effect, another limiting factor is that the [hk1]-oriented Sb2Se3, which is the ideal condition for PEC and photovoltaic cells, is not thermodynamically favorable compared to that of [hk0] orientation, as the [hk0] leads to the formation of Sb2Se3crystal facets with a lower formation energy.[33] To tackle this issue, studies have recently shown that [hk1]- oriented Sb2Se3film can be obtained by optimizing the selenization temperature of either the Sb or Sb2Se3film.[34,35]It is often reported that the employment of molybdenum (Mo) as the backcontact to grow [hk1]-oriented Sb2Se3film during the selenization step, however, Liang et al.[36]demonstrated that the in situ surface selenization of tungsten (W) can be used as a back-contact to enable the obtainment of Sb2Se3film featuring [hk1] preferred orientation. Furthermore, the authors reported that the thin layer of WSe2behaves as a hole transport layer, which means that this material can collect the photogenerated holes and block the photogenerated electrons from transferring to the back-contact, hindering the electron-hole recombination process. Herein, it is considered an alternative thermal treatment approach to obtain [001]-oriented Sb2Se3film. For this study, a new methodology was developed consisting of preliminary annealing of the Sb layer before the selenization step. Particularly, it was aimed to investigate the influence of the different annealing temperatures of the Sb layer and the different selenization conditions (i.e., temperature and dwelling time) of the annealed Sb layer to produce [001]-oriented Sb2Se3film. It was also targeted to assess how the crystallinity and elemental composition of the [001]-oriented Sb2Se3film directly affect the PEC performance for H2production via solar-driven water splitting. As will be shown in the Results and Discussion section, compared to the Sb2Se3 film obtained only via selenization, the annealing of the Sb layer before selenization led to the formation of Sb2Se3film with preferential crystallographic orientation to the [001] direction, better crystallinity, and suitable elemental composition. It will also be demonstrated that the Sb2Se3film obtained via annealing of Sb before selenization delivers a substantial improvement of PEC activity and stability for H2generation from the water splitting reaction. All in all, the annealing step developed in this work provides an alternative approach to considerably enhance PEC activity and stability of [001]-oriented Sb2Se3film for H2production. 2. Results and Discussion 2.1. Characterization of Single-Layered Films 2.1.1. Selenization of Non-Annealed Sb In this regard, the elemental composition of the Sb2Se3(Sb-NA) film submitted to selenization at 320 °C for 30 min was analyzed by XRF. According to Figure S3a, Supporting Information, the elemental composition of the film was Se-rich, presenting a maximum atomic percentage ratio of 3[Sb%]/2[Se%] ≈0.67, which is far from the stoichiometric value (3[Sb%]/2[Se%] =1, corresponding to 60 at.% Se and 40 at.% Sb). A brief investigation was performed over the range of selenization temperatures of 320 ±20 °C (i.e., 300 and 340 °C for 30 min), however, the films continued to present a Se-rich composition. Se-rich Sb2Se3films have also been reported as an effective stoichiometric condition Adv. Funct. Mater. 2025, 2506401 2506401 (2 of 16) © 2025 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH 16163028, 0, Downloaded from https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202506401 by Readcube (Labtiva Inc.), Wiley Online Library on [06/05/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License www.advancedsciencenews.com www.afm-journal.de for photovoltaic cell application due to the presence of benign defects, that is, SeSb antisites (shallow acceptors) and the difficulty of detrimental defects formation, such as selenium vacancies and SbSe antisites (deep donors).[37–39] 2.1.2. Annealing Temperature Effect of Sb In the attempt to find out the reason for obtaining Se-rich Sb2Se3(Sb-NA) films, XRD measurements were performed for the as-deposited Sb film not subjected to annealing step (labeled as Sb-NA), as well as for those annealed at 150, 200, and 250 °C for 30 min (labeled as Sb-A150, Sb-A200, and Sb-A250, respectively). As shown in Figure S3b, Supporting Information, it was identified weak reflections for the (003), (006), and (202) planes of the Sb-NA film, which were assigned to the rhombohedral Sb phase (Powder Diffraction File (PDF) no. 35–732). These peaks featured low intensity, suggesting poor crystallinity of the SbNA film. That may have prevented the formation of a more stoichiometric Sb2Se3film and affected its composition during the selenization process. However, the results for the as-deposited Sb films annealed at the highest temperatures, namely, Sb-A200 and Sb-A250 films, showed strong reflections and therefore more crystalline films compared to those of the Sb-NA and Sb-A150 films, which have weak reflections. As additional evidence of the annealing effect, it can be observed that a decrease of up to 21.5% of the full width at half maximum (FWHM) values for the (006) plane (Figure S3c,Supporting Information), indicating an increase in the size of the Sb crystallite as the annealing temperature increases. Interestingly, the Sb-A200 and Sb-A250 films featured a secondary phase of Sb2O3(PDF no. 75–1565) as noted by the peaks indexed to the (111), (222), and (444) planes, which are indicated by circled regions in the XRD patterns (cf. Figure S3b, Supporting Information). Although the annealing was performed under Ar atmosphere, this result indicates that the Sb films underwent thermal oxidation at annealing temperatures higher than 200 °C. Despite the presence of the Sb2O3secondary phase, the selenization process (performed at 320 °C) can convert all oxidized phases into Sb2Se3. According to Equations (1)and(2), which consider the reaction between Sb(s) and Se(g), and the reaction of Sb(s) and O2(g) both at 320 °C (corresponds to 593 K),[40,41]the formation of Sb2Se3is thermodynamically more favorable than Sb2O3and the selenization also allows any oxide residues to be converted into the Sb2Se3. Furthermore, elementary Se has a melting point of 221 °C,[42]and high vapor pressure,[43]which contributes to the chalconization in the absence of oxygen gas. The reader is referred to the Supporting Information (SI) for details about the calculation of the values of the molar Gibbs energy of reaction at 593 K (∆rG(593 K)) for the reactions in Equations (1)and(2). 2Sb(s)+3Se(g)→Sb2Se3(s)ΔrG(593 K)=−670.9kJmol −1(1) 2Sb(s)+3 2O2(g)→Sb2O3(s)ΔrG(593 K)=−546.8kJmol −1(2) 2.1.3. Selenization of Sb Annealed at Different Temperatures The as-deposited Sb films annealed at different temperatures were subsequently submitted to selenization and assessed their elemental composition by the XRF analysis (Figure 1a). It is possible to observe that the annealing of the Sb improved the stoichiometry of the Sb2Se3films, allowing the 3[Sb%]/2[Se%] atomic ratio of these films to increase compared to those of the Sb2Se3films obtained without annealing the Sb. This is indicative that more crystalline Sb films may lead to better formation of Sb2Se3phase in the selenization process. The best annealing condition before selenization was at 200 °C, as favored a maximum 3[Sb%]/2[Se%] atomic ratio of ≈0.8. The improvement of adjusted chemical composition might be attributed to a lesser extent elemental Se condensation over the surface of the Sb2Se3(SbA) films compared to those of Sb2Se3(Sb-NA) films. The elemental Se condensation may have occurred during the selenization process of the Sb-A and Sb-NA films.[44]The presence of elemental Se on the Sb2Se3(Sb-A) films’ surface was verified by XPS analysis (see discussion further). The minimized condensation of elemental Se for the Sb2Se3(Sb-A) films might be associated with the crystal structure of the [001]-oriented Sb-A films (see discussion of Figure 1b,c) that possibly favors diffusion of sublimated Se atoms into the [001]-oriented crystal lattice of the Sb-A film that can subsequently react to form [001]-oriented Sb2Se3.[45] The Sb2Se3films obtained via selenization of annealed Sb, as well as the Sb2Se3(Sb-NA) film, were also characterized by XRD measurements (see Figure 1b). All the diffractograms featured diffraction peaks indexed to the (020), (120), (220), (230), (211), (221), (301), (311), (240), (231), (141), (411), (002) and (061) planes, and these peaks were assigned to the orthorhombic Sb2Se3phase (PDF no. 89–821). The diffraction peaks labeled with asterisks (*) are attributed to the Mo-coated glass substrates (PDF no. 42–1120). Furthermore, it was not identified the diffraction peaks of the secondary phase of Sb2O3, proved the efficacy of the method of fully converting the Sb and Sb2O3phases into the Sb2Se3phase during selenization, as shown in Equations (1) and (2). Another interesting aspect from Figure 1b is that all the Sb2Se3films obtained via selenization of the annealed Sb showed strong reflections for the (002) plane compared to those of the Sb2Se3(Sb-NA) film, indicating better crystallinity and preferential orientation in the [001] direction. To better understand the preferred orientation of the crystallographic planes of the Sb2Se3 films, the texture coefficient for a given (hkl) plane, TC(hkl), was calculated using Equation (3),[27]and the results are displayed in Figure 1c. TC (hkl)=I(hkl) I0(hkl){1 N N ∑ i=0 I(hkl) I0(hkl)}−1 (3) where I(hkl)and I0(hkl)are the diffraction peak intensities for a given (hkl) plane measured from the XRD and the database of XRD (Sb2Se3PDF no. 89–821) patterns, respectively, and Nis the number of planes considered for the calculation (10 planes in that diffractogram). According to Figure 1c, the TC for the (120), (301), (221), and (211) planes featured similar values and were lower than 1, meaning no preferential crystal orientation for these planes. However, TC(230) >1 was achieved for the Sb2Se3(Sb-NA) and Sb2Se3(SbA150) films, suggesting that the crystal of Sb2Se3has a preferential growth orientation parallel to the substrate ([100] and/or [010] orientation), which is not efficient for photogenerated charge Adv. Funct. Mater. 2025, 2506401 2506401 (3 of 16) © 2025 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH 16163028, 0, Downloaded from https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202506401 by Readcube (Labtiva Inc.), Wiley Online Library on [06/05/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License www.advancedsciencenews.com www.afm-journal.de Figure 1. a) Atomic percentage ratio obtained from the XRF analysis, b) XRD patterns, and c) TC(hkl) values of the Sb2Se3(Sb-NA) and the Sb2Se3(Sb-A) films. XRD patterns of the PDF database for the orthorhombic Sb2Se3(PDF no. 89–821) and the cubic Mo (PDF no. 42–1120) phases are displayed as vertical lines at the bottom of the diffractograms. The diffraction peaks labeled with * were assigned to the Mo back-contact. carriers transportation due to inter-ribbons hopping mechanism. For the (002) plane, the Sb2Se3(Sb-A200) film featured the highest TC(002) value (i.e., ≈3), indicating the ribbons of the Sb2Se3 are vertically grown to the substrate ([001] orientation), which favor efficient photogenerated charge carriers transportation owing to the transport of the carriers alongside the ribbons. It was also noted that the Sb2Se3(Sb-A200) film has the lowest value for the TC(120), indicating low contribution of the parallel orientation to the substrate. This preferential growth of the [001] direction for the Sb2Se3has likely occurred due to the influence of the improved intensity of the diffraction peaks for the (003) and (006) planes ([001]-oriented Sb) of the Sb-A200 and Sb-A250 films compared to those of the Sb-A150 and Sb-NA films (cf. Figure S3b, Supporting Information). The (003) and (006) planes enable continuous diffusion of sublimated Se to react with [001]-oriented Sb and form column growth of [001]-oriented Sb2Se3.[45]To better understand this phenomenon in terms of a possible selenization mechanism, the change in temperature during the annealing process directly influences the vapor pressure of Se atoms and their kinetic energy. At a given selenization temperature, the sublimated Se atoms may adsorb on the [001]-oriented Sb film surface with sufficient energy to react and form a Sb2Se3crystal nucleus. The sublimated Se atoms may continue to diffuse to the [001]-Sb/[001]-Sb2Se3interface along the van Waals gaps of Sb2Se3to extend the length of the [001]-Sb2Se3preferential growth.[34,46] However, despite the Sb-A250 film featuring the highest intensity of the Sb’s diffraction peaks for the (003) and (006) planes, the presence of the Sb2O3phase may have minimized its preferential orientation in the [001] direction compared to that of the Sb2Se3(Sb-A200) film. Therefore, the experimental condition for the preparation of Sb2Se3(Sb-A200) film was chosen as the optimum condition. Additional characterization of the Sb2Se3(Sb-NA) and the Sb2Se3(Sb-A) films was achieved by Raman spectra, as shown in Figure 2. The main vibrational modes of Sb2Se3are represented by well-defined bands within a range of 50 – 300 cm−1.[44]The bands located at 210 and 190 cm−1are related to the Agmode of the Sb–Se–Sb bending vibrations of the Sb2Se3, while the small band ≈154 cm−1is assigned to the A2u vibration mode of the Sb– Sb bond. The observed bands at 120 and 80 cm−1are attributed to the Se–Se bending.[44,47]It is important to mention that none of the samples displayed the characteristic bands of the Sb2O3secondary phase in the Raman spectra (corresponding to the main bands at 254 and 450 cm−1[44]), however, all the samples presented low-intensity bands at 98 and 250 cm−1assigned to the presence of Se6ring (rhombohedral Se).[44,48]It has also been reported that Se-rich chalcogenide film can provide rhombohedral Se signals in that region, which arise from the excess of Se deposited on the samples’ surface.[49,50]The Raman spectra in this work suggest that the selenization process may have contributed to the occurrence of elemental Se on the surface of all the samples, and this agrees with the XRF analysis, which indicates that the Sb2Se3are Se-rich (cf. Figure 1a). Nevertheless, it was not identified Se phase in the XRD data (cf. Figure 1b), probably indicating that Se phase may be present in small quantities. Figure S4a,b, Supporting Information show the Tauc plots as (𝛼hv)1/2 versus Eph (indirect transition) and (𝛼ℎ𝜈)2versus Eph (direct transition), respectively.[51]For an indirect and a direct transition, the linear extrapolation to the baseline rendered optical Eg Adv. Funct. Mater. 2025, 2506401 2506401 (4 of 16) © 2025 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH 16163028, 0, Downloaded from https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202506401 by Readcube (Labtiva Inc.), Wiley Online Library on [06/05/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License www.advancedsciencenews.com www.afm-journal.de Figure 2. (on the left) Raman spectra and their corresponding (on the right) expanded region of the spectra encompassing the main bands of Sb2Se3 for the Sb2Se3(Sb-NA) and the Sb2Se3(Sb-A) films. values of 1.33 and 1.34 eV, respectively, for all the samples. These results are slightly higher than those reported in the literature (i.e., 1.1–1.3 eV[12–14]), however, it is also reported that Sb2Se3with higher optical Egfor nanorod[52,53]or nanowires[54]morphologies. In addition, it was also assessed the Euof the films, which characterizes the structural disorder of the semiconductor.[55]An increase of Euvalue represents an enlargement of the width of the bands’ edges tail, which means a more pronounced structural disorder in the semiconductor. This parameter can be understood as the width of the tail of the conduction and valence band edges associated with the localized defect states within the Eg. Additionally, the presence of the bands’ edges tailing corresponds to transitions between extended states of the valence band and localized states of the conduction band.[56]According to Figure S4c, Supporting Information, it can be seen a narrow linear region in the inset of the Euplot before the Egvalues, which the Euwas estimated from the inverse of the slope of the straight lines in the graphs. Unlike the optical Egvalue in which there was no difference in comparison with the different samples, the Euhas shown a slight difference in their values. The lowest value of the Euwas 0.21 eV for the Sb2Se3(SbA200) film compared to those of the other films. This indicates that the annealing at 200 °C of the Sb film has contributed to the decrease of the structural disorder and the localized defects in the band edges of the Sb2Se3(Sb-A200) film. On the other hand, the Sb2Se3(Sb-A250) film featured the highest value of the Eu(i.e., 0.32 eV), indicating that this film has a higher number of localized defects in its band edges compared to the other films.[57] The Sb2Se3(Sb-A200) film, that is, representing the optimum condition, was chemically assessed by the XPS measurements, and the spectra are displayed in Figure 3.AsshowninFigure3a, the survey spectrum exhibits the main peaks of Sb, Se, O, and C elements, corresponding to Sb 4p, Sb 3d, Sb 4s, Sb 4d, Se 3s, Se 3p, Se 3d, O 1s, and C 1s core levels, respectively. Regarding the high-resolution XPS spectra (Figure 3b), the spectrum of the Sb 3d core level features two Sb 3d doublets: the first one with peaks at 529 (Sb 3d5/2) and 538.34 eV (Sb 3d3/2) are assigned to the Sb–Se bonds in Sb2Se3, whereas the second one having peaks at 530 (Sb 3d5/2) and 539.34 eV (Sb 3d3/2) are attributed to the Sb– O bonds.[58]Since XPS is a highly surface-sensitive technique, the presence of an Sb–O signal is a result of the sample being exposed to air before the XPS analysis,[59]and this has also been reported in the literature.[60–62]The presence of Sb–O signal (possibly Sb2O3) might be beneficial as it could passivate defects (i.e., Se vacancies) on the surface of Sb2Se3films.[62]Moreover, bearing in mind that XPS is surface-sensitive (penetration depth of 10 nm or less[63]), despite the possibility of superficial formation of Sb2O3, the bulk properties of Sb2Se3films remain unaltered, as can be verified from the discussion of XRD (cf. Figure 1)and Raman (cf. Figure 2). Still regarding Figure 3b, The O 1s peak at 531.7 eV is assigned to the adventitious oxygen weakly adsorbed on the surface, which could also be a result of atmospheric CO2 physisorption on the photoelectrode surface.[64]Concerning the Adv. Funct. Mater. 2025, 2506401 2506401 (5 of 16) © 2025 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH 16163028, 0, Downloaded from https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202506401 by Readcube (Labtiva Inc.), Wiley Online Library on [06/05/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License www.advancedsciencenews.com www.afm-journal.de Figure 3. a) The survey and high-resolution XPS spectra of b) Sb 3d and c) Se 3d core levels for Sb2Se3(Sb-A200) film. high-resolution spectra of the Se 3d core level (Figure 3c), one notices the presence of two Se 3d doublets: the first one containing peaks at 53.5 (Se 3d5/2) and 54.36 eV (Se 3d3/2) are assigned to the Se–Sb bonds in Sb2Se3, and the second one with peaks at 54.9 (Se 3d5/2) and 55.76 eV (Se 3d3/2) are attributed to the Se–Se bonds in elemental selenium.[58]As shown in the discussion of the Raman spectra (cf. Figure 2), the presence of elemental selenium arises from the excess of Se in the form of Se6rings on the samples’ surface during the selenization process or even as a side-product of the Sb2Se3air oxidation. Besides the chemical assessment, it has employed SEM analyses (Figure 4) to characterize the morphology on the surface and at the cross-section of the Sb2Se3(Sb-NA) and the Sb2Se3(SbA) films. As indicated in Figure 4a, it is possible to observe the formation of rod-like structures with lengths of more than 1μm, which are randomly oriented in all directions on the surface of the Sb2Se3(Sb-NA) film. The presence of these rod-like structures may indicate a preferential orientation of the Sb2Se3 crystal. Since the Sb2Se3(Sb-NA) film featured preferential orientation to the (230) plane (cf. Figure 1c), this implies that the rod structures might be associated with the existence of (Sb4Se6)nribbons oriented at the [hk0] direction (i.e., ribbons horizontally oriented to the substrate).[33]For the Sb2Se3(Sb-A) films (cf. Figure 4a), the Sb2Se3(Sb-A150) film features a mix of morphologies on its surface, ranging from microrods to roundshaped structures. The morphology of the Sb2Se3(Sb-A200) film mostly consists of compacted irregular structures, whose contours are well-defined. On the other hand, the morphology of the Sb2Se3(Sb-A250) film presents a less-defined shape, including elongated and misshapen grains. The cross-section micrographs in Figure 4b showed differences in the films’ morphology. The Sb2Se3(Sb-NA) and Sb2Se3(Sb-A150) films show lessdefined grains, whereas the Sb2Se3(Sb-A250) film displays voids between the Sb2Se3and the tri-layer Mo. For the Sb2Se3(Sb-A200) film, one notices the presence of homogeneous and well-defined grains vertically grown on the tri-layer Mo with no voids between them. The formation of these vertically oriented structures for the Sb2Se3(Sb-A200) film suggests formation of [001]-oriented (Sb4Se6)nribbons,[33]as was also observed by the highest TC(002) value of ≈3 (see Figure 1c). All the morphological features of the Sb2Se3(Sb-A200) film can be better observed in the micrographs zoomed out of the surface and cross-section (Figure 4c). Regarding the thickness of the films, although it is not possible to accurately measure the thickness due to the non-uniformity, one notices that the thickness of the Sb2Se3(Sb-A) films is higher compared to that of Sb2Se3(Sb-NA) film (cf. Figure 4b). This apparent increase in thickness of the Sb2Se3(Sb-A) films is probably due to enlarged crystallite size of Sb-A films upon the annealing process, which can be observed by the decrease of up to 21.5% of the FWHM values for the (006) plane (Figure S3c, Supporting Information), representing an increase in ≈11 nm (according to the Scherrer equation) of the Sb crystallite size. 2.1.4. Optimizing Selenization of Annealed Sb According to the results that have been presented so far, the optimum thermal treatment condition corresponded to the sample labeled as Sb2Se3(Sb-A200). Aiming to further evaluate the thermal treatment approach of the Sb2Se3films, it has also been assessed the effect of the selenization on the Sb-A200 films at different temperatures (i.e., 280, 300, 320, and 340 °C) and dwelling times (i.e., 30 and 60 min). The Sb-A200 films selenized at different temperatures and times were characterized in terms of their elemental composition, crystal structure, and photoelectrocatalytic performance toward HER, as presented as follows. From the XRF analysis (Figure 5a), one notices that the SbA200 films selenized at the lowest temperature and time (i.e., 280 °C and 30 min, respectively) featured the highest atomic ratio of 0.81, which is reasonably close to the expected stoichiometric value. Additionally, the Se-rich condition became more pronounced for the Sb-A200 films selenized at the highest temperature and time (i.e., 340 °C and 60 min, respectively), leading to a minimum value of atomic ratio of 0.69. Based on these results, one can infer that longer dwelling times and higher temperatures can lead to a sublimated Se-rich atmosphere and significantly affect the composition of the samples. This result means that the employment of the annealing step for the Sb film and the simple Adv. Funct. Mater. 2025, 2506401 2506401 (6 of 16) © 2025 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH 16163028, 0, Downloaded from https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202506401 by Readcube (Labtiva Inc.), Wiley Online Library on [06/05/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License www.advancedsciencenews.com www.afm-journal.de Figure 4. FEG-SEM micrographs of the a) surface (20k times magnification) and b) the cross-section (100k times magnification) for the Sb2Se3(Sb-NA) and the Sb2Se3(Sb-A) films. c) FEG-SEM micrographs zoomed out of the surface (10k times magnification) and cross-section (50k times magnification) of the Sb2Se3(Sb-A200) film. adjustment of the selenization temperature and time play an important role in improving the stoichiometry of the Sb2Se3films. Concerning the XRD analysis (Figure 5b), the diffraction peaks of all the samples were assigned to the orthorhombic Sb2Se3 phase (which follows the PDF no. 89–821), and no secondary phase, such as elemental Se and Sb2O3, was detected. Additionally, all the samples have shown strong reflections in the diffraction peak indexed to the (002) plane as the most intense one, indicating better crystallinity and preferential orientation of the Sb2Se3crystal to the [001] direction. As additional analysis from the XRD patterns, it was also calculated the mean of crystallite size, D, from the diffraction peak positions via Equation (4)[65] for the Sb2Se3(Sb-A200) films selenized at different temperatures and dwelling times. D=K𝜆 𝛽cos 𝜃(4) where Kis the shape factor (0.9, considering the orthorhombic nature of Sb2Se3[65,66]), 𝜆is the X-ray wavelength (1.54 Åfor Cu K𝛼1radiation), 𝛽is the FWHM for a given diffraction peak, and 𝜃is the diffraction peak position. As shown in Figure 5c, a slight tendency was noted for the Dvalues of the samples selenized at different temperatures and dwelling times. For the dwelling time of 60 min, Dpresented values ranging from 107.85 to 116.41 nm with increasing selenization temperature, suggesting an increase in the grain size as the temperature increases. This increase of Dmay indicate that the crystallinity and grain size of the Sb2Se3film are affected upon selenization. Since the film becomes Se-rich as the selenization temperature increases, the atoms of Se may incorporate into the Sb2Se3structure[66]and increase its size. Conversely, for the dwelling time of 30 min, Dpresented a maximum value of 112.61 nm for the selenization temperature of 300 °C and then this value decreased for higher selenization Adv. Funct. Mater. 2025, 2506401 2506401 (7 of 16) © 2025 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH 16163028, 0, Downloaded from https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202506401 by Readcube (Labtiva Inc.), Wiley Online Library on [06/05/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License www.advancedsciencenews.com www.afm-journal.de Figure 5. a) Atomic percentage ratio obtained from the XRF analysis, b) XRD patterns, and c) Dvalues for the Sb2Se3(Sb-A200) films selenized at different temperatures and dwelling times. XRD patterns of the PDF database for the orthorhombic Sb2Se3(PDF no. 89–821) and the cubic Mo (PDF no. 42–1120) phases are displayed as vertical lines at the bottom of the diffractograms. The diffraction peaks labeled with * were assigned to the Mo from the Mo back-contact. temperatures. This decrease in the Dvalues of the Sb2Se3at selenization temperatures >300 °C is probably related to the partial decomposition of the Sb2Se3crystallites, as Sb2Se3can undergo thermal decomposition and/or structural rearrangement under high temperatures.[47,67] 2.2. Characterization of Multi-Layered Films Aiming to obtain a multilayer photocathode for the H2generation via solar-driven water splitting, the surface of the Sb2Se3(SbA200) film was initially etched with the KCN solution followed by the sequential deposition of the CdS and the TiO2layers onto their films’ surface to obtain the Sb2Se3(Sb-A200)/CdS/TiO2 films. Regarding the morphological analysis of the multilayer films, Figure S5 shows the surface micrographs obtained by FEGSEM at 20k times magnification for each of the layers present in the sample. The surface of the back-contact (tri-layer Mo) presented a worm-like morphology, whereas the Sb-A200 layer, which was deposited onto this back-contact, exhibited a morphology of irregular grains closely packed. For the Sb2Se3(SbA200) film, obtained by selenizing the Sb-A200 film at 320 °Cfor 30 min, one notices that the particles featured irregular shape and once the Sb2Se3(Sb-A200) film was etched with the KCN solution, the irregular shape of the particles was drastically affected by the etching process, suggesting a slight dissolution of the particles of this layer.[18]For the CdS layer, which was deposited over the KCN-etched Sb2Se3(Sb-A200) film, it was noted the presence of vertically grown plate-like structures and the occurrence of clusters distributed throughout the CdS film’s surface. For the upper layer, that is, TiO2, one notices the presence of a compact layer covering the whole film’s surface. As additional SEM image analyses, it was also obtained the cross-section micrograph of the SLG/Mo/Sb2Se3(SbA200)/CdS/TiO2film to measure the thickness of the layers (Figure 6a). The tri-layer Mo exhibited a total thickness of ≈0.9 μm, which was comprised of the denominated MoA (≈0.6 μm, lower region of the back-contact), and MoB+MoA (≈0.3 μm), corresponding to the porous (intermediate region of the Mo layer) and the sacrificial (upper region of the Mo layer) layers, respectively. It is worth mentioning that the difficulty in differentiating the porous and the sacrificial layers does not allow a proper distinction between them, however, the morphological characteristics of these layers are very similar to that reported in the literature.[68]It is also worth pointing out that the denomination of the layers in the tri-layer Mo (i.e., SLG/MoA/MoB/MoA) was based on the work developed by Lopez-Marino et al.,[68] who reported the tri-layer Mo was comprised of the MoAlayer (back-contact), deposited at high power and low pressure, MoB (resistant to selenization), deposited at low power and high pressure, and the MoAlayer (sacrificial layer). The MoAlayer is more compact and has excellent electrical properties, but it is easily overselenized, whereas the MoBlayer is more porous and has higher shunt resistance. The presence of a thin MoAlayer on the upper region acts as a sacrificial layer for the formation of MoSe2, and the interior selenization of the back-contact is prevented by the MoBlayer, leading thus the thick MoAlayer on the lower region unselenized, which acts as the back-contact for Adv. Funct. Mater. 2025, 2506401 2506401 (8 of 16) © 2025 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH 16163028, 0, Downloaded from https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202506401 by Readcube (Labtiva Inc.), Wiley Online Library on [06/05/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License www.advancedsciencenews.com www.afm-journal.de Figure 6. a) FEG-SEM cross-section micrograph (15k times magnification), b) EDS elemental mapping, and c) their respective elements for each layer present in the SLG/Mo/Sb2Se3(Sb-A200)/CdS/TiO2film. d) EDS scan line profile of the tri-layer Mo having on its surface the Sb2Se3(Sb-A200) film. the light absorber material. Regarding the cross-section micrograph of the other materials deposited on the tri-layer Mo, one notices a very compact layer of the Sb2Se3(SbA200)/CdS/TiO2 throughout the film’s cross-section with a thickness of ≈0.7 μm, presenting no voids between the absorber and the tri-layer Mo and no apparent delamination. The XRF analysis was used to estimate the thickness of Sb2Se3, whose value is ≈0.65 μm, sufficient to absorb photons within the wavelength range of 400– 1000 nm.[11,69]The CdS layer was estimated with a thickness of 50 nm, while TiO2was estimated with a thickness of ≈26 nm. The cross-section of the multilayer film was also chemically characterized via EDS elemental mapping, it was possible to distinguish the elements in the different layers (see Figure 6b,c,and Figure S6a, Supporting Information). Additionally, according to the EDS scan line analysis (Figure 6d) along the cross-section of the film, one notices the presence of Se (blue line) located within 0.6 and 0.9 μm (roughly below the Sb2Se3layer). That is due to the formation of a thick layer of MoSe2from the selenization of MoBand MoA(intermediate and upper region of Mo layer, respectively). The massive formation of MoSe2is prone to occur given that the molar Gibbs energies of the reaction of MoSe2and Sb2Se3are both negative (Equations (5)and(6)), considering the reaction between Mo(s) or Sb(s) with Se(g) at 320 °C (corresponds to 593 K).[40,41]For more details about the calculation of the values of the ∆rG(593 K) for these reactions, the reader is referred to the SI. The presence of an MoSe2interlayer can improve the contact quality between the absorber (i.e., Sb2Se3) and the back contact by forming a quasi-ohmic contact, resulting in a higher open-circuit voltage due to a reduced contact barrier and minimized series resistance.[70] Still concerning Figure 6d, it is noted that the presence of O (gray line) is located close to the lower region of the tri-layer Mo, and it is believed that this is from the glass substrate (i.e., SiO2). Also, no O signal was identified within the region of the Sb2Se3(Sb-A200) film, which ensures the absence of Sb2O3after the selenization process. Mo(s)+2Se(g)→MoSe2(s)ΔrG(593 K)=−503.9kJmol −1(5) 2Sb(s)+3Se(g)→Sb2Se3(s)ΔrG(593 K)=−670.9kJmol −1(6) The remaining elements, such as Si, Cd, and Ti did not affect the Sb2Se3layer, as can be seen in the EDS scan line complete analysis (Figure S6b, Supporting Information). Concerning the S element, it cannot be said how it affects the Sb2Se3since Mo and S elements have small energy differences (14 eV) by energy dispersive X-ray, and it is hard to distinguish Mo and S elements with the energy resolution in EDS.[71]As long as the substrate is a thick layer of Mo (0 to 0.9 μm), it can be inferred that the huge signal in this range is related to the Mo element. Additional chemical characterization was carried out for the Sb2Se3(Sb-A200)/CdS/TiO2film having on its surface deposited Pt, which was used as a cocatalyst to further improve the HER under illumination. The surface of the Sb2Se3(SbA200)/CdS/TiO2/Pt film was assessed via EDS elemental mapping, as shown in Figure S6c, Supporting Information. The data verify the presence of Pt as well as Sb and Se, and these elements are well-distributed throughout the surface of the samples. 2.3. PEC Assessment The PEC performance of the Sb2Se3(Sb-A200) films obtained from the selenization of Sb-A200 films at different Adv. Funct. Mater. 2025, 2506401 2506401 (9 of 16) © 2025 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH 16163028, 0, Downloaded from https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202506401 by Readcube (Labtiva Inc.), Wiley Online Library on [06/05/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License www.advancedsciencenews.com www.afm-journal.de [58] J. F. Moulder, W. F. Stickle, P. E. Sobol, K. D. Bomben, Handbook of Xray Photoelectron Spectroscopy, 2nd ed. (Ed: J. Chastain), Perkin-Elmer Corporation, Eden Prairie, 1992. [59] T. Meyer, A. Girard, M. Bouška, E. Baudet, M. Baillieul, P. N˘ emec, V. Nazabal, C. Cardinaud, Plasma Sources Sci. Technol. 2023,32, 085003. [60] M. Luo, M. Leng, X. Liu, J. Chen, C. Chen, S. Qin, J. Tang, Appl. Phys. Lett. 2014,104, 173904. [61] A. K. Jain, C. Gopalakrishnan, P. Malar, J. Mater. Sci.: Mater. Electron. 2022,33, 10430. [62] S. Wen, X. Yin, H. Xie, Y. Guo, J. Liu, D. Liu, W. Que, H. Liu, W. Liu, J. Adv. Dielectr. 2020,10, 2050016. [63] F. A. Stevie, C. L. Donley, J. Vac. Sci. Technol., A 2020,38, 063204. [64] C. H. Don, H. Shiel, T. D. C. Hobson, C. N. Savory, J. E. N. Swallow, M. J. Smiles, L. A. H. Jones, T. J. Featherstone, P. K. Thakur, T.-L. Lee, K. Durose, J. D. Major, V. R. Dhanak, D. O. Scanlon, T. D. Veal, J. Mater. Chem. C 2020,8, 12615. [65] J. I. Langford, A. J. C. Wilson, J. Appl. Crystallogr. 1978,11, 102. [66] S. Kim, H. You, K. Yun, J. Kim, T. Seong, Adv. Opt. Mater. 2023,11, 2201974. [67] P. Vidal-Fuentes, M. Guc, I. Becerril-Romero, D. Sylla, X. Alcobé, Y. Sánchez, A. Pérez-Rodríguez, E. Saucedo, V. Izquierdo-Roca, Sol. RRL 2021,5, 2100517. [68] S. Lopez-Marino, M. Espíndola-Rodríguez, Y. Sánchez, X. Alcobé, F. Oliva, H. Xie, M. Neuschitzer, S. Giraldo, M. Placidi, R. Caballero, V. Izquierdo-Roca, A. Pérez-Rodríguez, E. Saucedo, Nano Energy 2016, 26, 708. [69] A. Mavlonov, T. Razykov, F. Raziq, J. Gan, J. Chantana, Y. Kawano, T. Nishimura, H. Wei, A. Zakutayev, T. Minemoto, X. Zu, S. Li, L. Qiao, Sol. Energy 2020,201, 227. [70] S.-N. Park, S.-Y. Kim, S.-J. Lee, S.-J. Sung, K.-J. Yang, J.-K. Kang, D.-H. Kim, Mater. Adv. 2022,3, 978. [71] J. Y. Kim, P. Lindgren, Y.-J. Zhang, S. K. Kim, T. M. Valentin, H.-T. Jung, A. A. Peterson, Mater. Adv. 2021,2, 4867. [72] M. B. Costa, M. A. de Araújo, R. Paiva, S. A. Cruz, L. H. Mascaro, J. Chem. Eng. 2024,485, 149526. [73] C. Batchelor-McAuley, Curr. Opin. Electrochem. 2023,37, 101176. [74] S. Chen, T. Liu, Z. Zheng, M. Ishaq, G. Liang, P. Fan, T. Chen, J. Tang, J. Energy Chem. 2022,67, 508. [75] Y. Wang, Y. Chen, Y. Yun, X. Hong, Y. Huang, H. Ji, Appl. Catal., B 2024, 358, 124375. [76] X. Chen, X. Li, Y. Peng, H. Yang, Y. Tong, M.-S. Balogun, Y. Huang, Adv. Funct. Mater. 2024,25, 2416091. [77] J. H. Kim, J. S. Lee, Adv. Mater. 2019,31, 1970146. [78] K. Lee, T.-H. Kim, S.-H. Jo, S. Yu, Chemosphere 2024,354, 141675. [79] D. Klotz, D. A. Grave, A. Rothschild, Phys.Chem.Chem.Phys.2017, 19, 20383. [80] K. J. Tiwari, M. Neuschitzer, M. Espíndola-Rodriguez, Y. Sánchez, Z. Jehl, P. Vidal-Fuentes, E. Saucedo, P. Malar, Sol. Energy Mater. Sol. Cells 2020,215, 110603. [81] M. Bär, B.-A. Schubert, B. Marsen, S. Krause, S. Pookpanratana, T. Unold, L. Weinhardt, C. Heske, H.-W. Schock, Appl. Phys. Lett. 2011, 99, 152111. [82] D.-C. Nguyen, K. Fukatsu, K. Tanimoto, S. Ikeda, M. Matsumura, S. Ito, Int. J. Photoenergy 2013,2013,1. [83] M. E. Erkan, V. Chawla, I. Repins, M. A. Scarpulla, Sol. Energy Mater. Sol. Cells 2015,136, 78. [84] Y. Guo, J. Jiang, S. Zuo, F. Shi, J. Tao, Z. Hu, X. Hu, G. Hu, P. Yang, J. Chu, Sol. Energy Mater. Sol. Cells 2018,178, 186. [85] O. Vigil-Galán, J. A. Andrade-Arvizu, M. Courel-Piedrahita, C. MejíaGarcía, E. Valencia-Resendíz, Y. Sánchez-González, M. EspíndolaRodríguez, E. Saucedo-Silva, R. González-Castillo, E. RodríguezGonzález, D. Seuret-Jiménez, D. Jiménez-Olarte, J. Mater. Sci.: Mater. Electron. 2017,28, 18706. [86] X. Zhang, G. Lu, Y. Wu, J. Dong, C. Wang, Catal. Sci. Technol. 2021, 11, 5505. [87] K. T. Fountaine, H. J. Lewerenz, H. A. Atwater, Nat. Commun. 2016, 7,1. [88] C. A. Schneider, W. S. Rasband, K. W. Eliceiri, Nat. Methods 2012,9, 671. [89] L. Zeng, Z. Zhao, F. Lv, Z. Xia, S.-Y. Lu, J. Li, K. Sun, K. Wang, Y. Sun, Q. Huang, Y. Chen, Q. Zhang, L. Gu, G. Lu, S. Guo, Nat. Commun. 2022,13, 3822. [90] R. R. Prabhakar, T. Moehl, S. Siol, J. Suh, S. D. Tilley, Chem. Mater. 2020,32, 7247. [91] N. Fairley, V. Fernandez, M. Richard-Plouet, C. Guillot-Deudon, J. Walton, E. Smith, D. Flahaut, M. Greiner, M. Biesinger, S. Tougaard, D. Morgan, J. Baltrusaitis, Appl. Surf. Sci. Adv. 2021,5, 100112. [92] M. Nowak, B. Kauch, P. Szperlich, Rev. Sci. Instrum. 2009,80,1. [93] P. Makuła, M. Pacia, W. Macyk, J. Phys. Chem. Lett. 2018,9, 6814. [94] L. Dejam, J. Sabbaghzadeh, A. Ghaderi, S. Solaymani, R. S. Matos, Ș. Ț˘ alu, H. D. da Fonseca Filho, A. H. Sari, H. Kiani, A. H. S. shayegan, M. A. Doudaran, Sci. Rep. 2023,13, 6518. [95] L. Wang, C. Lee, P. Schmuki, J. Mater. Chem. A 2013,1, 212. Adv. Funct. Mater. 2025, 2506401 2506401 (16 of 16) © 2025 The Author(s). Advanced Functional Materials published by Wiley-VCH GmbH 16163028, 0, Downloaded from https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202506401 by Readcube (Labtiva Inc.), Wiley Online Library on [06/05/2025]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License