Modulation of interface electric field over CoMoP-CoMoP2 heterostructure for high-efficiency oxygen evolution reaction

•CoMoP-CoMoP2 heterostructure nanofibers were prepared for the first time.•Built-in interfacial electric fields optimizing adsorption of key intermediates.•CoMoP-CoMoP2 heterostructure lowers the rate-determining step barrier of OER.•Overpotentials of OER are 184 mV and 302 mV to deliver 10 and 100 mA cm−2. The construction of a heterostructure can significantly enhance the intrinsic activity of the electrocatalysts. In this study, a simple electrospinning combined with post-treatment strategy is successively employed to fabricate novel CoMoP-CoMoP2 heterostructure nanofibers. Experimental results and density functional theory (DFT) calculations demonstrate that the formation of CoMoP-CoMoP2 heterointerface can optimize the kinetics of the oxygen evolution reaction (OER) and enhance the intrinsic catalytic activity. As anticipated, the resulting CoMoP-CoMoP2 electrocatalyst displays outstanding OER performance (184 mV @ 10 mA cm−2, and 302 mV @100 mA cm−2) as well as excellent stability in 1 M KOH. Moreover, the OER test results of CoMoP-CoMoP2 with varying CoMoP and CoMoP2 contents indicate that CoMoP-CoMoP2-1 (with a mass ratio of approximately 1.01/10.1) exhibits the highest OER activity. Utilized as the overall water splitting electrocatalyst, CoMoP-CoMoP2-1 demonstrates exceptional durability and outperforms Pt/C||RuO2 electrolyzer, achieving a current density of 10 mA cm−2 and a battery voltage of only 1.53 V during continuous operation for 260 h. These findings suggest the practical application potential of this material, confirming the promising nature of bimetallic phosphide-bimetallic phosphide heterostructure electrocatalysts.