A Fe-Ni5P4/Fe-Ni2P heterojunction electrocatalyst for highly efficient solar-to-hydrogen generation

Hydrogen generation through solar-driven water splitting is a promising green technology for the sustainable development of human society; however, its wide application is severely restricted by the expensive noble-metal electrocatalysts. Herein, a novel Fe-Ni5P4/Fe-Ni2P (H-FeNiP) heterojunction electrocatalyst is developed by simultaneously taking advantage of the heterojunction effect and the doping effect. It shows excellent activity for both the oxygen and hydrogen evolution reactions in alkaline solution, which only require overpotentials of 231 +/- 3 mV and 86 +/- 8 mV to deliver 10 mA cm(-2), respectively. Density functional theory (DFT) calculations reveal that the heterojunction structure can induce charge transfer from the underlying layer to the surface, which is effective in reducing the activation energy barrier for the HER and OER intermediates. This favorable activity enables the H-FeNiP couple to exhibit an impressive solar-to-hydrogen performance when connected with an organic solar cell (PTB7-Th/PC71BM/CO(i)8DFIC), the power conversion ratio of which (73.10%) is even higher than that of the commercial Pt||RuO2 couple (69.98%). Overall, this study conceptually provides an alternative avenue for cost-effective hydrogen generation in an environmentally friendly manner for the future.

Automated summary

This study developed a novel heterojunction electrocatalyst for efficient oxygen and hydrogen evolution reactions under alkaline conditions. The heterojunction structure induces charge transfer, reducing the activation energy barrier for these reactions. This alternative avenue for cost-effective hydrogen generation shows impressive solar-to-hydrogen performance.