Coordination Tailoring of Pt Single-Atom Catalysts at Room Temperature and Their Exceptional Performance in Hydrogen Evolution Reaction

Single-atom catalysts (SACs) have garnered interest in designing their ligand environments, facilitating the modification of single catalytic sites toward high activity and selectivity. Despite various synthetic approaches, it remains challenging to achieve a catalytically favorable coordination structure simultaneously with the feasible formation of SACs at low temperatures. Here, a new type of coordination structure for Pt SACs is introduced to offer a highly efficient hydrogen evolution reaction (HER) catalyst, where Pt SACs are readily fabricated by atomically confining PtCl₂ on chemically driven NO₂ sites in two-dimensional nitrogen-doped carbon nanosheets at room temperature. The resultant Pt SACs form the NO₂–Pt–Cl₂ coordination structure with an atomic dispersion, as revealed by X-ray spectroscopy and transmission electron microscopy investigations. Moreover, our first-principles density functional theory (DFT) calculations show strong interactions in the coordination by computing the binding energy and charge density difference between PtCl₂ and NO₂. Pt SACs, established on the NO₂-functionalized carbon support, demonstrate the onset potential of 25 mV, Tafel slope of 40 mV dec⁻¹, and high specific activity of 1.35 A mg_Pt⁻¹. Importantly, the Pt SACs also exhibit long-term stability up to 110 h, which is a significant advance in the field of single-atom Pt catalysts. The newly developed coordination structure of Pt SACs features a single Pt active center, providing hydrogen binding ability comparable to that of Pt(111), enhanced long-term durability due to strong metal-support interactions, and the advantage of room-temperature fabrication.