Modulating d-p orbital hybridization via W self-intercalation concentration in bilayer WSe_x (x ≤ 2) for...

Electrocatalytic water splitting serves as a green energy alternative and represents a crucial pathway for sustainable hydrogen production, yet its widespread application is hindered by the limited efficiency of catalysts. A fundamental challenge to the rational design of high-performance catalysts arises from the limited efficiency of catalysts and the high energy barriers in reaction processes, making their development a significant scientific endeavor, making the rational design of high-performance catalysts a significant scientific endeavor. Herein, we engineered bifunctional electrocatalysts for HER/OER based on W self-intercalation bilayer 2H/2 M-WSe_x (x ≤ 2) materials, where bilayer 2H-WSe_1.52 and 2 M-WSe_1.78 exhibit excellent catalytic activity with overpotentials of 0.17/0.51 V and 0.002/0.50 V, respectively. Mechanistic studies revealed that self-intercalation W atoms modulate the electronic structure by redistributing charge density, lifting orbital degeneracy, and inducing energy-level splitting, thereby enhancing electrical conductivity. Crucially, the concentration of W intercalants governs the degree of d-p orbital hybridization, which directly correlates with catalytic performance. To exploit this property, we systematically design bilayer 2H/2 M-WSe_x structures with tailored W intercalation concentrations to optimize their catalytic activity. Through comprehensive characterization-including overpotential analysis, d-band center evaluation, the Bader charge analysis, density of states (DOS), the crystal orbital Hamilton population (COHP), and work function measurements-we elucidate the influence of intercalation concentration on electronic properties. This work not only provides a strategic framework for phase engineering of high-efficiency electrocatalysts but also highlights the potential of self-intercalation materials for multifunctional synergistic applications.