Anchoring Pt single atoms on 3D flower-like NiMoP via PtNi bonding with enhanced hydrogen evolution reaction

Introducing Pt single atoms (Pt_SA) into bimetallic phosphides to enhance their performance at higher current densities remains a significant challenge under alkaline conditions. We successfully anchored Pt_SA on 3D flower-like NiMoP through a PtNi bonding method. The 3D flower-like catalyst (Pt_SA@NiMoP) exhibits remarkably low overpotentials, requiring only 35 mV to achieve 10 mA cm^-2 and 66 mV at 100 mA cm^-2. Moreover, Pt_SA@NiMoP demonstrates a Tafel slope of 29.1 mV dec^-1 and maintains stability for 50 h at different current densities in 1.0 M KOH solution. After the introduction of Pt_SA, the average NiNi bond length increases to 2.525 Å, accompanied by a significant decrease in the NiNi coordination number, indicating the successful formation of PtNi bonds. Density functional theory (DFT) calculations reveal that Pt_SA accelerates water dissociation on the NiMoP surface and facilitates electron transfer from Ni to P, enhancing H⁺ reduction and promoting the Volmer step. Additionally, the hydrogen adsorption Gibbs free energy (ΔG_H*) of Pt_SA@NiMoP is only -0.065 eV (close to 0 eV), which is favorable for H₂ evolution. Meanwhile, the Pt serves as an active site that further accelerates H₂ generation, synergistically improving the catalytic kinetics of the alkaline hydrogen evolution reaction (HER).