In-Situ construction of hierarchically porous CoNiP/MP Ni electrocatalyst for overall water splitting

Constructing self-supported electrocatalysts is recognized as a practical implement to promote the electrocatalytic performance of water splitting. Herein, bimetallic phosphide CoNiP grown on a micro-sized porous nickel substrate (MP Ni) as electrocatalyst (CoNiP/MP Ni) has been developed to decrease the overpotentials of hydrogen evolution and oxygen evolution reaction. The micro-sized porous nickel substrate provides adequate specific surface area for loading active materials, and the hierarchically porous structure offers numerous interconnected channels, which together accelerates the mass transfer process in the electrocatalytic reaction. The CoNiP/MP Ni electrocatalyst achieves an ultra-low overpotentials of 37 mV at 10 mA center dot cm(-2) and 358 mV at 100 mA center dot cm(-2) for driving hydrogen evolution and oxygen evolution, respectively. The stable porous structure also enables the integrated CoNiP/MP Ni electrolyzer an excellent long-term operation stability. Meanwhile, first-principles calculations demonstrate that the CoNiP bimetallic phosphide possesses a low energy barrier and a strong interfacial bonding strength with micro-sized porous Ni from an atomic viewpoint. This work opens up a simple and new way of constructing low-cost, efficient and applicable self-supported electrocatalysts for water splitting.

Automated summary

Constructing self-supported electrocatalysts is important for enhancing the performance of water splitting. In this study, a bimetallic phosphide CoNiP grown on a micro-sized porous nickel substrate showed low overpotentials for hydrogen and oxygen evolution reactions. The micro-sized porous nickel substrate provided a large surface area for active material loading, and the hierarchically porous structure facilitated mass transfer in the electrocatalytic reaction. The CoNiP/MP Ni electrocatalyst achieved ultra-low overpotentials and stable operation, making it a promising candidate for water splitting.