Stable Tensile-Strained Pt Single Atomic Layer Catalysts on α-MoC for Efficient Alkaline Hydrogen Evolution

Developing Pt-based core-shell catalysts with ultralow Pt loading, superior performance, and extended durability holds tremendous potential for advancing electrochemical energy storage and conversion technologies. However, current synthetic limitations persist in achieving atomically efficient Pt monolayer deposition on nonprecious metal substrates, hindering the maximization of Pt atomic utilization for cost-effective catalyst design. Here, we demonstrate a galvanic replacement strategy to synthesize tensile-strained platinum single-atom-layer (Pt SAL) on α-MoC substrates. The Pt SAL catalysts enable cooperative catalysis between adjacent Pt sites while maintaining nearly 100% atomic utilization efficiency. For alkaline hydrogen evolution, the Pt SAL/α-MoC catalyst exhibits optimized reaction energetics, reducing activation barriers for water dissociation, hydrogen adsorption, and H₂ desorption compared to typical Pt/C. As a result, the Pt SAL catalysts exhibit superior hydrogen evolution reaction (HER) performance, with a mass activity of 1.71 A mg_Pt^-1 at an overpotential of 50 mV, surpassing commercial Pt/C by 6.35-fold and single-atom catalysts by 7.68-fold. Remarkably, the Pt SAL catalysts reveal negligible activity decay after 10,000 cycles, with density functional theory (DFT) calculations attributing this stability to strong Pt-Mo interfacial bonding. <i>In situ</i> Raman spectroscopic studies reveal dynamic interfacial water restructuring that accelerates reaction kinetics. This work establishes a versatile synthesis approach for noble metal SAL catalysts and explores their role in designing high-performance electrocatalysts for heterogeneous catalysis.