Rational design of bimetal phosphide embedded in carbon nanofibers for boosting oxygen evolution

The development of non-precious metal electrocatalysts for oxygen evolution reaction (OER) is crucial for generating large-scale hydrogen through water electrolysis. In this work, bimetal phosphides embedded in electrospun carbon nanofibers (P-FeNi/CNFs) were fabricated through a reliable electrospinning-carbonization-phosphidation strategy. The incorporation of P-FeNi nanoparticles within CNFs prevented them from forming aggregation and further improved their electron transfer property. The bimetal phosphides helped to weaken the adsorption of O intermediate, promoting the OER activity, which was confirmed by the theoretical results. The as-prepared optimized P-Fe₁Ni₂/CNFs catalyst exhibited very high OER electrocatalytic performance, which required very low overpotentials of just 239 and 303 mV to reach 10 and 1000 mA cm^-2, respectively. It is superior to the commercial RuO₂ and many other related OER electrocatalysts reported so far. In addition, the constructed alkaline electrolyzer based on the P-Fe₁Ni₂/CNFs catalyst and Pt/C delivered a cell voltage of 1.52 V at 10 mA cm^-2, surpassing the commercial RuO₂||Pt/C (1.61 V) electrolyzer. It also offered excellent alkaline OER performance in simulated seawater electrolyte. This demonstrated its potential for practical applications across a broad range of environmental conditions. Our work provides new ideas for the ration design of highly efficient non-precious metal-based OER catalysts for water electrolysis.