Engineering Atomic-Step Architectures in 2D WSe through Kinetic Modulation for Efficient Hydrogen Evolution in PEM Electrolyzers.

Hydrogen evolution reaction (HER) in proton exchange membrane (PEM) electrolyzers currently depends predominantly on platinum-based catalysts, whose high cost and limited natural abundance drive the urgent need for developing efficient non-precious alternatives. Among various candidates, tungsten-based transition metal dichalcogenides (TMDs, where X = S, Se, Te) have shown particular promise as cost-effective catalysts, yet their performance still falls short of practical requirements. Recognizing that the edge sites of TMDs serve as the primary active centers for HER, a strategy is developed to dramatically enhance WSe's catalytic efficiency by creating abundant atomic steps through a precisely controlled kinetically-driven selenization process. The engineered stepped WSe exhibits exceptional HER performance, achieving a remarkably low overpotential of 97 mV at 100 mA/cm with a Tafel slope of 38.69 mV/dec. Furthermore, it demonstrates outstanding practicality in PEM electrolyzers, requiring only 1.82 V to reach 1000 mA/cm and maintaining stable operation for 200 hours. DFT calculations reveals that the atomic steps create nearly thermoneutral hydrogen adsorption Gibbs free energy, which accounts for the superior activity. This work establishes an innovative approach for designing high-efficiency HER electrocatalysts via atomic-scale edge structure engineering, presenting a viable solution to reduce reliance on precious catalysts in PEM electrolyzer technologies.