Nitrogen and sulfur dual-doped high-surface-area hollow carbon nanospheres for efficient CO₂ reduction

The electrochemical reduction of CO₂ (CO₂RR) can substantially contribute to the production of useful chemicals and reduction of global CO₂ emissions. Herein, we presented N and S dual-doped high-surface-area carbon materials (SZ-HCN) as CO₂RR catalysts. N and S were doped by one-step pyrolysis of a N-containing polymer and S powder. ZnCl₂ was applied as a volatile porogen to prepare porous SZ-HCN. SZ-HCN with a high specific surface area (1510 m² g^−g1) exhibited efficient electrocatalytic activity and selectivity for CO₂RR. Electrochemical measurements demonstrated that SZ-HCN showed excellent catalytic performance for CO₂-to-CO reduction with a high CO Faradaic efficiency (~93%) at −0.6 V. Furthermore, SZ-HCN offered a stable current density and high CO selectivity over at least 20 h continuous operation, revealing remarkable electrocatalytic durability. The experimental results and density functional theory calculations indicated that N and S dual-doped carbon materials required lower Gibbs free energy to form the COOH* intermediate than that for single-N-doped carbon for CO₂-to-CO reduction, thereby enhancing CO₂RR activity.