The direct electroreduction of CO2 provides a promising route to produce valuable chemicals and achieve a negative carbon cycle. However, its selectivity is still limited by the transport and surface coverage of key intermediates, especially the insufficient local CO2 supply and the inadequate *CO accumulation needed for C2+ formation. Here, we design an S-doped Cu2O catalyst (SP-Cu2O) with a tailored microstructure that simultaneously enhances CO2 delivery and enables the mechanistic evaluation of S-induced selectivity under CO2-enriched conditions. Hydrophobic surface engineering promotes the formation of a symmetric hydrogen-bond network, enriching CO2 near the catalyst interface. Operando FTIR-SEIRAS and DFT calculations reveal that this enriched microenvironment boosts *CO generation, while sulfur doping downshifts the Cu d-band center, facilitating the desorption and migration of *CO and *COH and suppressing excessive *COH hydrogenation─ultimately promoting C–C coupling. Consequently, 1% SP-Cu2O achieves a C2+ Faradaic efficiency of 79.4% and a partial current density of 302.4 mA cm–2 at −1.2 V vs the reversible hydrogen electrode. This strategy offers a generally applicable route to improving CO2 utilization efficiency across diverse catalyst systems, thereby enhancing the sustainability of future CO2.
Liu et al. (2026) studied this question.