V8C7 decorating CoP nanosheets-assembled microspheres as trifunctional catalysts toward energy-saving electrolytic hydrogen production

Abstract

Hydrogen production via water electrolysis for large scale application is still limited majorly by the huge energy consumption and high cost of catalyst materials. In this work, with rationally designing V/Co metal-organic framework (V/Co-MOF) as a precursor, a series of V8C7 decorating CoP nanosheets-assembled microspheres (V8C7/CoP) was synthesized via pyrolysis and a subsequent phosphidation. Thanks to the synergistic effect between V8C7 and CoP, the optimized V8C7/CoP as trifunctional catalysts exhibit remarkable performance toward hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and urea oxidation reaction (UOR). More importantly, we propose an acid-alkaline asymmetric-electrolyte electrolyzer (AAAE) by using the optimized V8C7/CoP electrode as both acidic cathode for HER and alkaline anode UOR, respectively. The optimum AAAE system only needs an applied voltage of 0.8 V to reach an electrolytic current density of 10 mA cm−2 for hydrogen production, which significantly reduces the energy consumption for hydrogen production owing to the assistance of electrochemical neutralization energy (ENE) and electrochemical urea oxidation energy.