Heterogeneous Bimetallic Phosphide Ni2P-Fe2P as an Efficient Bifunctional Catalyst for Water/Seawater Splitting

Developing high-performance and cost-effective bifunctional electrocatalysts for large-scale water electrolysis is desirable but remains a significant challenge. Most existing nano- and micro-structured electrocatalysts require complex synthetic procedures, making scale-up highly challenging. Here, a heterogeneous Ni2P-Fe2P microsheet is synthesized by directly soaking Ni foam in hydrochloric acid and an iron nitrate solution, followed by phosphidation. Benefiting from high intrinsic activity, abundant active sites, and a superior transfer coefficient, this self-supported Ni2P-Fe2P electrocatalyst shows superb catalytic activity toward overall water splitting, requiring low voltages of 1.682 and 1.865 V to attain current densities of 100 and 500 mA cm(-2)in 1mKOH, respectively. Such catalytic performance is superior to the benchmark IrO2 || Pt/C pair and also places this electrocatalyst among the best bifunctional catalysts reported thus far. Furthermore, its enhanced corrosion resistance and hydrophilic surface make it suitable for seawater splitting. It is able to achieve current densities of 100 and 500 mA cm(-2)in 1mKOH seawater at voltages of 1.811 and 2.004 V, respectively, which, together with its robust durability, demonstrates its great potential for realistic seawater electrolysis. This work presents a general and economic approach toward the fabrication of heterogeneous metallic phosphide catalysts for water/seawater electrocatalysis.

Automated summary

The study successfully synthesized a heterogeneous Ni2P-Fe2P microsheet electrocatalyst with superior catalytic activity and corrosion resistance, suitable for water and seawater electrolysis, demonstrating great potential. The catalyst has abundant active sites and a superior transfer coefficient, exhibiting performance even better than the currently reported best bifunctional catalysts.