Modulating electronic structure of nickel diselenide by vanadium doping toward highly efficient and stable bifunctional electrocatalysts for overall water splitting

Designing low-cost and high-efficiency bifunctional electrocatalysts is one of the challenges in the clean production of hydrogen energy in electrochemical water splitting. Transition metal selenides (TMSes) have been widely studied because of their low price, intrinsic metal properties, and high catalytic activity. In addition, the synergistic effect between bimetallic selenides exhibits better performance than monometallic selenides in the electrocatalytic process. Herein, we synthesized V-doped NiSe2 nanowire arrays on pretreated nickel foam by a convenient two-step hydrothermal synthesis method. In the alkaline electrolyte, V-NiSe2/NF exhibited excellent OER catalytic activity (293.6 mV@50 mA cm–2). In addition, the introduction of heteroatom V induces stronger electronic interactions between the structural atoms of the catalyst, altering the electronic structure and causing V-NiSe2/NF to demonstrate excellent OER performance. In the long-term OER test, V-NiSe2/NF was converted into NiOOH and SeOx2–, which may be the “real” active species during catalytic reactions, and we also successfully captured the formation of intermediate NiOOH and selenite as active centers in the OER process through in-situ Raman. The theoretical calculation shows that the electron transfer modulates the electron structure, changes the adsorption-desorption energy of the reaction intermediates, reduces the potential barrier of the rate-limiting step, and improves the OER activity. The V doping engineering strategy and the unique nanowire array structure make TMSes exhibit excellent OER performance. This study provides a new idea for the design of TMSe catalysts with excellent electrocatalytic performance.