Exquisite restructuring of the electronic structure of cobalt phosphide via rationally controlling iron induction for water splitting under industrial conditions

Abstract

Rational designing of high-efficiency bifunctional electrocatalysts for industrial water splitting and the understanding of their intricate catalytic mechanisms remain a huge challenge. Herein, ultrathin iron-doped cobalt phosphide (Fe–CoP) nanosheets were prepared via hydrothermal, oxidation and phosphating routes. The incorporation of Fe in the CoP matrix greatly ameliorated the electronic structure and charge transfer ability of the targeted product. In addition, the Fe–CoP substance with a unique ultrathin nanosheet architecture increased the number of active sites and promoted electron transfer, leading to improved oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities. As anticipated, the Fe–CoP catalyst displayed outstanding bifunctional properties with overpotentials of only 249 and 78.5 mV at 10 mA cm⁻², and Tafel slopes of 43.1 and 60.7 mV dec⁻¹ were obtained for OER and HER, respectively. Simultaneously, an electrolyzer was assembled with Fe–CoP as the two electrodes required just 1.37 V to reach 10 mA cm⁻² for water splitting along with good stability in an industrial environment (60 °C, 6.0 M KOH). The density functional theory (DFT) calculations disclosed that the incorporation of Fe into CoP efficaciously optimized the electronic structure to accelerate the adsorption and desorption of *H and the formation of the crucial intermediate*OOH, thereby yielding excellent electrocatalytic performance. Our findings provide a facile and feasible approach for designing highly active catalysts for actual electrolytic water applications.