“Similar stacking”-inspired compressive strain of heterogeneous phosphide for efficient hydrogen evolution

Abstract

Strain effects have garnered significant attention in catalytic applications due to their ability to modulate the electronic structure and surface adsorption properties of catalysts. In this study, we propose a novel approach called “similar stacking” for stress modulation, achieved through the loading of Co₂P on Ni₂P (Ni₂P/Co₂P). Theoretical simulations reveal that the compressive strain induced by Co₂P influences orbital overlap and electron transfer with hydrogen atoms. Furthermore, the number of stacked layers can be adjusted by varying the precursor soaking time, which further modulates the strain range and hydrogen adsorption. Under a 2-h soaking condition, the strain effect proves favorable for efficient hydrogen production. Experimental characterizations using X-ray diffraction, high-angel annular dark-field scanning transmission election microscope (HAADF-STEM), and X-ray absorption near-edge structure spectroscopy successfully demonstrate lattice contraction of Co₂P and bond length shortening of Co–P. Remarkably, our catalyst shows an ultrahigh current density of 1 A cm^–2 at an overpotential of only 388 mV, surpassing that of commercial Pt/C, while maintaining long-term stability. This material design strategy of similar stacking opens up new avenues of strain modulation and the deeper development of electrocatalysts.

Keywords

compressive strain / heterogeneous phosphide / hydrogen evolution reaction / similar stacking

Author summay

Tianyi Xu and Dongxu Jiao contributed equally to this study.