Inherent vacancy of compressive Ru nanoparticles accelerate electro-catalytic hydrogen energy conversion

Single factor such as defect or strain is adopted to regulate Ru-based catalysts for HER and HOR, which usually fail to accurately describe the complex catalysis. Herein, ultrafine Ru nanoparticles with vacancies and compressive stress are formed on carbon (V-S-Ru/C) as revealed by electronic and spectroscopic characteriza-tions. This V-S-Ru/C has excellent HER activity with a low overpotential of 21 mV to deliver 10 mA/cm2, and the mass activity is 35.6 times that of commercial Pt/C at 100 mV overpotential. The V-S-Ru/C could also achieve 7.2 times mass activity of commercial Pt/C for HOR and has oxidation resistance in high potential range. The V-S-Ru/C shows lower barrier of rate-determining step, because the defect and strain synergistically induce the upshift of d-band center on Ru to promote the adsorption of key intermediates based on theoretical calculation. The cooperative regulation of defect and strain provide a new pathway for mechanism insight and designing catalyst.