Tantalum doping triggered electronic reconfiguration of cobalt phosphide for efficient and stable overall seawater splitting.

The design of pre-catalysts is crucial for constructing highly durable and active seawater oxidation catalysts. In this work, a Ta-CoP catalyst for overall seawater splitting was successfully synthesized via an orbital electron interaction strategy, where Tantalum (Ta) was selected as the doping element, which enables strong interaction with the d-orbital electrons of cobalt (Co). Ta doping significantly alters the coordination environment of Co, leading to a notable increase in the charge density within the Co(P) bond. This unique electronic structural feature effectively suppresses the continuous oxidation of the Ta-CoP catalyst during the oxygen evolution reaction (OER). During the electrochemical oxidation process in an alkaline solution, Ta-CoP nanosheets are in-situ transformed into Ta-CoOOH, forming a Ta-CoP@Ta-CoOOH core@shell structure. The inner Ta-CoP core optimizes the electronic structure of Co active sites in the outer Ta-CoOOH catalytic reaction layer, significantly enhancing catalyst stability by reducing Cl occupation of active sites and inhibiting Cl corrosion. The potential increase of Ta-CoP@Ta-CoOOH core@shell catalyst after stable operation for 100 h at a current density of 500 mA cm in a 1 M KOH + 0.5 M NaCl solution is only 3 mV, much lower than the potential increase of CoP@CoOOH (100 mV). Additionally, in natural seawater durability tests, the Ta component further enhances the material's long-term stability by suppressing catalyst structural collapse. Mechanistically, Ta-CoP strengthens the interaction between Co active sites and the *O intermediate, thereby improving OER catalytic activity. Moreover, Ta doping induces charge redistribution in Co atoms, achieving ideal electron mobility and enhancing hydrogen evolution reaction (HER) activity. This study highlights the potential of the orbital electron interaction strategy in the development of high-performance bifunctional electrocatalysts.