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Context : Previous theoretical studies have suggested that two-dimensional (2D) MBene materials might display adequate monatomic catalytic activity for the hydrogen evolution reaction (HER). Recently, a study reported the experimental synthesis of a 2D MBene (Mo4/3B2), re-defined as boridene, albeit no effort has been devoted to explore the single-atom catalytic activity for HER of this experimentally synthesized 2D material. Therefore, we herein investigate the single-atom HER performance of the boridene. Interestingly, with Mo defects mixed with single Au and Zn atoms shows excellent hydrogen evolution performance, and the change in the Gibbs free energy ( Δ G H ) value is close to 0 eV, which can even match the performance of Pt-based materials. Through analysis of the charge density difference and density of states, the mechanism affecting the HER performance is explained at the electronic level. This work provides a new direction for the use of the Mo4/3B2 monolayer two-dimensional materials in the field of single-atom catalysis for HER. Methods: This study used the DFT calculations in Vienna ab initio simulation package. The GGA-Perdew-Burke-Ernzerhof functional with DFT-D2 correction is used to describe the exchange–correlation interactions. The projection augmented wave is used with the plane wave cutoff of 500 eV. The convergences of energy and force are 10−5 eV and 0.01 eV/Å, respectively. A vacuum layer with a height of 20 Å is set in the Z direction. For geometry optimization, self-consistent, and DOS calculations, the k-point grids sampled in Brillouin zones are 3 × 3 × 1, 9 × 9 × 1, and 9 × 9 × 1, respectively. The AIMD simulation is performed in the canonical ensemble (NVT), and the temperature was maintained at 300 K by Nosé-Hoover thermostats with a time step of 2.0 fs. [ABSTRACT FROM AUTHOR]

Single transition‐metal atom coordinated graphite carbon nitride, including the metal atom doped g‐C3N4 system, displays catalytic activity comparable to that of the noble metal Pt catalyst with outstanding performance. Herein, we investigate the single atom catalytic performance of g‐C3N3 embedded by a single transition metal atom (M−C3N3; M=Mn, Fe, Co, Ni, Cu, Rh, Pd, Ag, and Pt) for hydrogen evolution reaction (HER) using density functional theory (DFT) calculations. The results indicate that all the M−C3N3 catalysts are thermally and dynamically stable systems. By comparing the Gibbs free energies, we found that the Rh−C3N3 catalyst exhibits the best HER electrocatalytic performance among the investigated systems. Subsequently, analysis of electronic structure indicates that the Rh−C3N3 system displays a metallic behavior, which is a beneficial feature for an adequate HER electrocatalyst. Finally, the charge density difference of the Rh−C3N3 structure further supports the rationality of our results. This study provides a new candidate of low‐cost, high‐performance, and highly active non‐noble metal electrocatalysts. [ABSTRACT FROM AUTHOR]