First-Principles Calculations and Machine Learning of Hydrogen Evolution Reaction Activity of Nonmetallic Doped β-Mo₂C Support Pt Single-Atom Catalysts

The most widely used catalyst for the hydrogen evolution reaction (HER) is Pt, but the high cost and low abundance of Pt need to be urgently addressed. Single-atom catalysts (SACs) have been an effective means of improving the utilization of Pt atoms. In this work, we used a nonmetal (NM = B, N, O, F, Si, P, S, Cl, As, Se, Br, Te, and I) doped β-Mo₂C (100) C-termination surface as the support, with Pt atoms dispersed on the support surface to construct Pt@NM-Mo₂C. Using density functional theory (DFT) calculations, we selected catalysts with excellent HER activity. Among 117 candidate catalysts, 49 catalysts exhibited ideal catalytic performance with Gibbs free energy of hydrogen intermediate (H*) adsorption (Δ<i>G</i>_H*) values less than 0.2 eV. The Δ<i>G</i>_H* values of 16 catalysts were even lower than that of Pt (Δ<i>G</i>_H* ≈ 0.09 eV), with Pt_I@N_2/4-a-Mo₂C demonstrating the best performance (Δ<i>G</i>_H* = -0.01 eV). Combined with electronic structure analysis, we could understand the impact of charge transfer between Pt and the underlying NM atoms on the strength of the Pt-H bond, thereby promoting HER activity. Using machine learning (ML), we identified that the primary influencing factors of the HER catalytic activity in the Pt@NM-Mo₂C system were the Bader charge transfer of Pt (<i>N</i>_ePt), the d-band center of Pt (ε_dPt), and the atomic radius of NM (<i>R</i>_NM), with <i>N</i>_ePt having the greatest impact on the HER catalytic activity.