One-Step Syntheses of Face-Centered Cubic Os_xPt_1-x/C with Near-Zero-Overpotential Hydrogen Evolution from...

The loading states and crystal structure control of solid solution catalysts, which greatly influence the catalytic performance, have not yet been achieved simultaneously due to the limitations of previous synthetic methodologies. In this work, a one-pot in situ polyol method is developed for the phase-control synthesis of face-centered cubic (fcc)-dominated and well-dispersed immiscible Os_xPt_1-x/C. Most fcc-Os_xPt_1-x/C catalysts exhibit superior hydrogen evolution reaction (HER) catalytic activities compared to those of Pt/C catalysts. Remarkably, the overpotential of fcc-Os_0.3Pt_0.7/C in 0.5 m H₂SO₄ at 10 mA·cm^-2 is only 1.0 mV as the top record. In Os_0.5Pt_0.5/C and Os_0.3Pt_0.7/C, the weakening of H adsorption on Pt sites, resulting from electronic state adjustments induced by Os alloying, modify the reaction pathways by promoting H₂ desorption from more favorable coupled sites, thereby achieving state-of-the-art HER catalytic activities.