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Synthesis and characterization of M(II) phosphonates (M = Fe, Co, Zn, Mn) as precursors for PEMFCs electrocatalysts

López Vergara, Adrián,Salcedo, Inés R.,Bazaga-García, Montse,Olivera-Pastor, Pascual,Cabeza-Díaz, Aurelio,Losilla, Enrique R.,Porras-Vázquez, José Manuel

Published
2018-11-01
Repository
riuma.uma.es
Language
en

Abstract

Metal phosphonates are promising precursors for applications such as proton conductivity [1] and catalysis [2]. Specifically, upon calcination metal polyphosphates are generated that can be used as non-noble metal alternatives [3] to the highly expensive commercial catalysts (Pt) for proton exchange membrane fuel cells (PEMFCs). In this work, we present the synthesis and characterization of metal polyphosphates obtained from transition divalent metal phosphonates (M= Fe, Mn, Co and Zn) both as monometallic and bimetallic systems (solid solutions). For the preparation of the metal phosphonate precursors, two types of organic linkers were selected, i.e. 2-R,S-hydroxiphosphonoacetic acid [HO3PCH(OH)COOH, HPAA] and nitrilotrismethylenephosphonic acid [N(CH2PO3H2)3, ATMP]. The as synthesized compounds were calcined between 700 and 1000 ºC under N2. Depending on the metal/phosphorous molar ratio in the precursor phases, different compositions were found, the corresponding metal pyrophosphate being the major component according to the crystallographic data. Interestingly, in most of cases the solid solutions were preserved in the final product, for instance Fe-Mn, Fe-Co and Fe-Zn. All calcined materials have been also characterized by XPS, SEM/EDS, FTIR-Raman.

Full text

XV Simposio de Jó enes In es igado es Químicos (Toledo, 2018) SYNTHESIS AND CHARACTERIZATION OF M(II) PHOSPHONATES (M = Fe, Co, Zn, Mn) AS PRECURSORS FOR PEMFCs ELECTROCATALYSTS A. López-Ve ga a1, I. R. Salcedo1, M. Bazaga-Ga cía1, P. Oli e a-Pas o 1, A. Cabeza1, E. R. Losilla1, J. M. Po as-Vazquez1. 1 Depa amen o de Química Ino gánica, Uni e sidad de Málaga, 290071-Málaga, Spain. [email p o ec ed] Me al phosphona es a e p omising p ecu so s o applica ions such as p o on conduc i i y [1] and ca alysis [2]. Speci ically, upon calcina ion me al polyphospha es a e gene a ed ha can be used as non-noble me al al e na i es [3] o he highly expensi e comme cial ca alys s (P ) o p o on exchange memb ane uel cells (PEMFCs). In his wo k, we p esen he syn hesis and cha ac e iza ion o me al polyphospha es ob ained om ansi ion di alen me al phosphona es (M= Fe, Mn, Co and Zn) bo h as monome allic and bime allic sys ems (solid solu ions). Fo he p epa a ion o he me al phosphona e p ecu so s, wo ypes o o ganic linke s we e selec ed, i.e. 2-R,S- hyd oxiphosphonoace ic acid [HO3PCH(OH)COOH, HPAA] and ni ilo isme hylenephosphonic acid [N(CH2PO3H2)3, ATMP]. The as syn hesized compounds we e calcined be ween 700 and 1000 C unde N2. Depending on he me al/phospho ous mola a io in he p ecu so phases, di e en composi ions we e ound, he co esponding me al py ophospha e being he majo componen acco ding o he c ys allog aphic da a. In e es ingly, in mos o cases he solid solu ions we e p ese ed in he inal p oduc , o ins ance Fe-Mn, Fe-Co and Fe-Zn. All calcined ma e ials ha e been also cha ac e ized by XPS, SEM/EDS, FTIR-Raman. Re e ences [1] A. Cabeza, P. Oli e a-Pas o , R.M. Pé ez Colod e o. O ganic-Ino ganic Ma e ials 2015 ed. E. B une , J.L.Colón, A. Clea ield, John Wiley & Sons, Inc.:Ch. 4, p. 137-192. [2] Clea ield, A.; Demadis, K.D. Me al Phosphona e Chemis y: F om Syn hesis o Applica ions, Royal Socie y o Chemis y, Camb idge, U.K., 2012. [3] I. Akhme o a, K. Schu jajew, M. Wilke, A. Buzanich, K. Rademann, C. Ro h, F. Emme ling. J. Ma e Sci. 2018, Volume 53, Issue 19, pp 13390–13399. 10 20 30 40 50 60 10 20 30 40 50 60 Fe2P2O7 FeHPAA Fe2P2O7+ Fe3O4 Fe2P2O7 Fe2P4O12 FeATMP Fe2P2O7 Fe2P2O7 700oC 900oC 1000oC RT