This study constructs 196 transition metals (TM)@S_xN_y single-atom catalysts (SACs) (x = 0–4 and y = 0–4) and employs the eXtreme Gradient Boosting (XGBoost) classification model in machine learning (ML) for effectively distinguishing qualified and unqualified catalysts. The prediction accuracy rate is high, up to 95%. The SHapley Additive exPlanations (SHAP) analysis reveals that the N≡N bond length and the number of outermost d electrons (N_d) can well describe the nitrogen (N₂) reduction reaction (NRR) activity. The relationships between N≡N, N_d, the adsorption energies of different intermediates ( $\mathrm{\Delta }{E}_{{\ast }_{{\text{N}}_2}}$, $\mathrm{\Delta }{E}_{{\ast }_{{\text{N}}_2\text{H}}}$, and $\mathrm{\Delta }{E}_{{\ast }_{{\text{N}\text{H}}_2}}$), the general descriptor (φ), and the Gibbs free energy of key steps ( $\mathrm{\Delta }{G}_{{\ast }_{{\text{N}}_2}}$, $\mathrm{\Delta }{G}_{{\ast }_{{\text{N}}_2-}{\ast }_{{\text{N}}_2\text{H}}}$, and $\mathrm{\Delta }{G}_{{\ast }_{{\text{N}\text{H}}_2-}{\ast }_{{\text{N}\text{H}}_3}}$) indicate that moderate nitrogen activation can enhance the reaction activity. Among the 17 screened SACs, Mo@S₃N₁, and W@S₃N₁ demonstrate the best catalytic performance, with limiting potential (U_L) values of only −0.26 and −0.25 V under implicit solvation conditions. The electronic properties and variations in N≡N and TM–N bond lengths are investigated to reveal the origin of NRR activity. This study provides the decisive features and NRR dataset for ML research, as well as a feasible strategy for rational design of NRR SACs.

Grain boundaries (GBs) play a crucial role on the structural stability and mechanical properties of Cu and its alloys. In this work, molecular dynamics (MD) simulations are employed to study the effects of Fe solutes on the formation energy, excess volume, dislocations and melting behaviors of GBs in CuFe alloys. It is illustrated that Fe solute affects the structural stability of Cu GBs substantially, the formation energy of GBs is reduced, but the thickness and melting point of GBs are increased, that is, the structural stability of Cu GBs is significantly improved owing to the Fe solutes. A strong scaling law exists between the formation energy, excess volume, thickness and melting point of GBs. Therefore, Fe solid solute plays an important role in the characteristics of GBs in bi-crystal Cu.

III-V semiconductors such as GaAs are widely studied as promising candidates for high-speed integrated circuit. Despite these applications for conventional bulk structures, their fundamental physical properties in the nanoscale limit are still in scarcity, which is of great importance for the development of nanoelectronics. In this work, we demonstrate that the III-V semiconductor MX (M = Al, Ga, In; X = P, As, Sb) in its two-dimensional (2D) limit could exhibit double layer honeycomb (DLHC) configuration and distorted tetrahedral coordination, according to our first-principles calculations with HSE06 hybrid functional. It is found that surface reconstruction endows 2D III-V DLHCs with pronouncedly different electronic and magnetic properties from their bulk counterparts due to strong interlayer coupling. Mexican-hat-shape bands emerge at the top valence bands of pristine AlP, GaP, InP, AlAs, and InAs DLHCs, inducing the density of states showing a sharp van Hove singularity near the Fermi level. As a result, these DLHCs exhibit itinerant magnetism upon moderate hole doping, while the rest GaAs, AlSb, GaSb, and InSb DLHCs become magnetic under tensile strain with hole doping. With an exchange splitting of the localized p_z states at the top valence bands, the hole-doped III-V DLHCs become half-metals with 100% spin-polarization. Remarkably, the InSb DLHC shows inverted band structure near the Fermi level, bringing about nontrivial topological band structures in stacked InSb DLHC due to the strong spin-orbital coupling. These III-V DLHCs expand the members of 2D material family and their exotic magnetic and topological properties may offer great potential for applications in the novel electronic and spintronic devices.

The catalyst innovation that aims at noble-metal-free substitutes is one key aspect for future sustainable hydrogen energy deployment. In this paper, a nickel cobalt sulfoselenide/black phosphorus heterostructure (NiCoSe|S/BP) was fabricated to realize the highly active and durable water electrolysis through interface and valence dual-engineering. The NiCoSe|S/BP nanostructure was constructed by in-situ growing NiCo hydroxide nanosheet arrays on few-layer BP and subsequently one-step sulfoselenization by SeS₂. Besides the conductive merit of BP substrate, holes in p-type BP are capable of oxidizing the Co²⁺ to high-valence and electron-accepting Co³⁺, benefiting the oxygen evolution reaction (OER). Meanwhile, Ni³⁺/Ni²⁺ ratio in the heterostructure is reduced to maintain the electrical neutrality, which corresponds to the increased electron-donating character for boosting hydrogen evolution reaction (HER). As for HER and OER, the heterostructured NiCoSe|S/BP electrocatalyst exhibits small overpotentials of 172 and 285 mV at 10 mA cm⁻² (η₁₀) in alkaline media, respectively. And overall water splitting has been achieved at a low cell potential of 1.67 V at η₁₀ with high stability. Molecular sensing and density functional theory (DFT) calculations are further proposed for understanding the rate-determine steps and enhanced catalytic mechanism. The investigation presents a deep-seated perception for the electrocatalytic performance enhancement of BP-based heterostructure.