In-situ surface reconstruction of Si enables highly selective and stable electrocatalytic synthesis of ethylene glycol

The in-situ reconstruction of catalysts has increasingly garnered research interest due to its pivotal role in modulating selectivity and improving activity. The surface reconstruction of group IVA element-based compounds under reaction conditions has been rarely investigated, despite wide application as active sites or carriers in catalyst fabrication. In this work, the heavy-period element in group IVA exhibits high activity in the electrocatalytic reduction of formaldehyde (HCHO) with H2O, which is attributed to the accelerated proton-coupled electron transfer by strong HCHO adsorption. Remarkably, the proper reconstruction of metallic Si to Si-OH during the electrolysis accounts for the active surface, enabling a highly selective formation of ethylene glycol (EG). Competitive long-term stability (1500 h) is demonstrated at –200 mA cm–2 with a low-resistance Si sheet as the cathode, which highlights the industrialization prospects of this alternative route for EG production. In-situ catalyst reconstruction can tune electrochemical selectivity, but its role in group IVA element-based catalysts remains underexplored. Here, the authors show that controlled Si-to-Si-OH reconstruction promotes selective formaldehyde reduction to ethylene glycol.