Accelerating the Screening of Modified MA₂Z₄ Catalysts for Hydrogen Evolution Reaction by Deep Learning-Based Local Geometric Analysis

Machine learning (ML) integrated with density functional theory (DFT) calculations have recently been used to accelerate the design and discovery of single-atom catalysts (SACs) by establishing deep structure–activity relationships. The traditional ML models are always difficult to identify the structural differences among the single-atom systems with different modification methods, leading to the limitation of the potential application range. Aiming to the structural properties of several typical two-dimensional MA₂Z₄-based single-atom systems (bare MA₂Z₄ and metal single-atom doped/supported MA₂Z₄), an improved crystal graph convolutional neural network (CGCNN) classification model was employed, instead of the traditional machine learning regression model, to address the challenge of incompatibility in the studied systems. The CGCNN model was optimized using crystal graph representation in which the geometric configuration was divided into active layer, surface layer, and bulk layer (ASB-GCNN). Through ML and DFT calculations, five potential single-atom hydrogen evolution reaction (HER) catalysts were screened from chemical space of 600 MA₂Z₄-based materials, especially V₁/HfSn₂N₄(S) with high stability and activity (ΔG_H* is 0.06 eV). Further projected density of states (pDOS) analysis in combination with the wave function analysis of the SAC-H bond revealed that the SAC-dz² orbital coincided with the H-s orbital around the energy level of −2.50 eV, and orbital analysis confirmed the formation of σ bonds. This study provides an efficient multistep screening design framework of metal single-atom catalyst for HER systems with similar two-dimensional supports but different geometric configurations.