WO3 based solid solution oxide – promising proton exchange membrane fuel cell anode electro-catalyst

Abstract

There is a vital need to develop novel non-noble metals based electro-catalyst or reduced noble metal containing electro-catalyst with excellent electrochemical activity and stability fostering economic commercialization of proton exchange membrane fuel cells (PEMFCs). It is hence of paramount importance to identify and generate reduced noble metal containing electro-catalyst with high electrochemical active surface area, offering noble metal loadings in the ultra-low levels thus reducing the overall capital cost of PEMFCs. Using theoretical first principles d-band center calculations of tungsten trioxide (WO₃) based electro-catalysts containing IrO₂ as a solute for hydrogen oxidation reaction (HOR), we have identified, synthesized and experimentally demonstrated a highly active nanostructured (W_1−xIr_x)O_y (x = 0.2, 0.3; y = 2.7–2.8) electro-catalyst for HOR. Furthermore, experimental studies validate superior electrochemical activity of nanostructured (W_0.7Ir_0.3)O_y for HOR exhibiting improved/comparable stability/durability contrasted to pure WO₃ nanoparticles (WO₃-NPs), IrO₂ nanoparticles (IrO₂-NPs) as well as state of the art commercial 40% Pt/C system. Optimized composition of (W_0.7Ir_0.3)O_y was identified exhibiting ∼33% higher and almost similar electro-catalytic activity for HOR compared to IrO₂-NPs and commercial 40% Pt/C catalyst, respectively. Additionally, (W_0.7Ir_0.3)O_y showed significant enhancement in electrochemical activity for HOR compared to pure WO₃-NPs. Long-term life cycle test of (W_0.7Ir_0.3)O_y for 24 h also showed comparable electrochemical stability/durability compared to that of 40% Pt/C and pure WO₃-NPs. The results of half and full cell electrochemical characterization bode well with the theoretical first principles studies demonstrating the promise of the WO₃ based solid solution electro-catalyst.