Pt Atom-Substituted\nMoC Single-Atom Catalyst for Enhancing\nH<sub>2</sub> Production

Single-atom\ncatalysts with a maximum atom utilization\nefficiency\nhave shown great potential for application in energy conversion and\nstorage fields. Herein, a highly stable single-atom Pt catalyst (Pt<sub>1</sub>/α-MoC) on α-MoC nanoribbons with Pt loading up\nto 2% is fabricated using an atom substitution strategy for the water–gas\nshift (WGS) reaction, which exhibits a very high H<sub>2</sub> production\nrate of 1094 μmol<sub>CO</sub>/g<sub>cat</sub>s at 200 °C,\nindicating one of the highest activity levels compared with the reported\nstate-of-the-art WGS catalysts. Complementary advanced characterizations,\nincluding aberration-corrected scanning transmission electron microscopy\n(STEM), synchrotron X-ray absorption spectroscopy (XAS), and density\nfunctional theory (DFT) calculations, demonstrate that single Pt atoms\nare uniformly dispersed on the outermost surface of α-MoC and\nstrongly confined within the crystalline lattice of molybdenum carbides.\nIn situ spectroscopic studies and DFT calculations reveal that the\nPt-MoC interface serves as a primary active site of the water gas\nshift (WGS) reaction, boosting H<sub>2</sub>O molecule activation,\nto form the key OH* intermediates. Our findings offer an efficient\nmethod for the rational design of high-activity single-atom catalysts\nand lay a good foundation for their industrial application.