Electrochemical fabrication of Fe-based binary and ternary phosphide cathodes for proton exchange membrane water electrolyzer

Abstract

The development of high-performance gas diffusion electrodes is essential for the fabrication of efficient proton exchange membrane water electrolyzers (PEMWEs) and thus for clean hydrogen production. Herein, we electrodeposited Fe-based binary and ternary phosphides on porous carbon paper (CP) as a substrate and demonstrated that, under optimized deposition conditions (i.e. when the P content was maximum), amorphous FeCoP showed the highest intrinsic activity for hydrogen evolution in an acidic medium. This behavior was ascribed to appropriate electronic structure modification and the alloying effect. Further enhancement of hydrogen evolution performance was achieved by increasing the electrochemical surface area of FeCoP by using a porous Cu foam (CF) support. In a half-cell test, the FeCoP/CF/CP electrode featured an acceptably stable cathodic current of −10 mA/cm2 at an overpotential of −125 mV. A PEMWE single cell with an FeCoP/CF/CP cathode exhibited a current density of 0.95 A/cm2 at a cell voltage of 2.0 V, which is superior to or comparable with previously reported values. Thus, the developed electrode might be a promising alternative to Pt-based cathodes in practical PEMWE applications.