Atomically Thin Holey Two-Dimensional Ru₂P Nanosheets for Enhanced Hydrogen Evolution Electrocatalysis

The defect engineering of low-dimensional nanostructured materials has led to increased scientific efforts owing to their high efficiency concerning high-performance electrocatalysts that play a crucial role in renewable energy technologies. Herein, we report an efficient methodology for fabricating atomically thin, holey metal-phosphide nanosheets with excellent electrocatalyst functionality. Two-dimensional, subnanometer-thick, holey Ru₂P nanosheets containing crystal defects were synthesized via the phosphidation of monolayer RuO₂ nanosheets. Holey Ru₂P nanosheets exhibited superior electrocatalytic activity for the hydrogen evolution reaction (HER) compared to that exhibited by nonholey Ru₂P nanoparticles. Further, holey Ru₂P nanosheets exhibited overpotentials of 17 and 26 mV in acidic and alkaline electrolytes, respectively. Thus, they are among the best-performing Ru-P-based HER catalysts reported to date. In situ spectroscopic investigations indicated that the holey nanosheet morphology enhanced the accumulation of surface hydrogen through the adsorption of protons and/or water, resulting in an increased contribution of the Volmer-Tafel mechanism toward the exceptional HER activity of these ultrathin electrocatalysts.