Unified Descriptor for Designing Electrocatalyst toward Arsine Synthesis

Arsine (AsH3) is an important electronic specialty gas, yet its synthesis still relies heavily on hazardous thermochemical processes, motivating the development of safe and mild electrocatalytic routes. Here, we establish a unified descriptor framework based on Gad(AsH) to decode the complex six-electron-transfer reaction network involved in electrocatalytic AsH3 synthesis from HAsO2 and its competition with the hydrogen evolution reaction (HER). Sure independence screening and sparsifying operator (SISSO) analysis further reveals that AsH* adsorption is associated with anisotropic dyz and dz2 orbital interactions rather than the conventional averaged d-band-center picture. Within this framework, Cu is predicted to achieve an optimal balance between AsH* stabilization and hydrogen supply, thereby promoting AsH3 formation while suppressing the competing HER pathway, with both thermodynamic favorability and kinetic feasibility. Experimental results further validate the prediction, with Cu delivering the highest AsH3 output (>7.5 × 104 ppm within 3 h). This work provides mechanistic and electronic-structure insights into electrocatalytic AsH3 synthesis and offers a descriptor-guided strategy for the electrochemical production of high-value electronic specialty gases.