Low power consumed PV-electrolysis with CoFeP nanowires for hydrazine-assisted hydrogen production

Abstract

Water electrolysis is becoming increasingly important in green hydrogen production. However, it consumes large amount of power due to sluggish oxygen evolution reaction (OER). Recently, hydrazine oxidation reaction (HzOR) attracted significant attention in replacing OER owing to its low oxidation potential. In this study, CoFeP nanowires (NWs) are presented as a novel effective HzOR electrocatalyst. An array of CoFeP NWs was directly synthesized on a cobalt foam (CF) by cation exchange and subsequent phosphorization. Fe doping on CoP changes rate determine step of hydrazine degradation, required less energy of 0.17 eV, confirmed by DFT calculation. Our CoFeP/CF exhibited high HzOR activity with a low potential of −7 mV for generating a current density of 10 mA cm−2 and a Tafel slope of 29 mV dec−1, which is superior to noble metal catalysts. The overall hydrazine splitting (OHzS) of the combined Pt/CF||CoFeP/CF required remarkably low cell potential of only 63 mV to generate a current density of 10 mA cm−2. Furthermore, the unassisted solar hydrogen production was realized by assembling Pt/CF||CoFeP/CF with a single perovskite solar cell, generating a high current generation of 23 mA cm−2. This value is about two times higher than that of an unassisted overall water splitting system with a solar to hydrogen efficiency of 13.1%, confirming a great potential of our OHzS system in lowering power consumption of electrolysis.