Engineering Cu/ZnO_x Interface For High Methane Selectivity In CO₂ Electrochemical Reduction

Thus far,Cu catalyst is still the sole known active metal for directly reducing CO₂to various hydrocarbons.Nevertheless,pure copper shows poor selectivity to single hydrocarbon,which greatly limits its application.Therefore,it is necessary to engineer Cu-based surface to tune its electronic structure and enhance the selectivity of desire reduction products.Recent studies suggest surface Cu sites of higher oxidation state may facilitate the formation of high energy density hydrocarbons.However,Cu^δ+are easily reduced under CO₂ reduction condition,leading to the obviously drop of CO₂reduction performance.Therefore,it is important to protect surface active Cu^δ+sites from being reduced for the CO₂ electroreduction catalysts.ZnO_x is prone to form strong interactions with other atoms via electron transfer,improving the stability of the catalysts structure.Therefore,from the perspective of stabilizing Cu^δ+sites on the surface to adjust the adsorption strength of reaction intermediates,we report a novel OD-Cu Zn catalyst with Cu/ZnO_x interface structure and its CO₂ electroreduction reaction mechanism.（1）We synthesized OD-Cu Zn catalyst by magnetron-sputtering and liquid-phase oxidation-reduction treatment and constructed Cu/ZnO_x interface structure,realizing the control of stable Cu^δ+content on the surface of catalysts.（2）Combined with SEM,XRD,XPS,AES,in-situ Raman and CO₂ reduction reaction test,it is revealed that the interface structure of Cu/ZnO_x stabilize surface Cu²⁺during CO₂ electroreduction reaction.Meanwhile,based on the positive correlation between the content of Cu²⁺on the surface and the selectivity of methane,we pointed out that Cu²⁺is likely to be the characteristic active site of CO₂-to-CH₄ conversion.（3）The theoretical calculations demonstrated that electron transfer between Cu foil and ZnO_xNPs is the reason why Cu²⁺can exist stably on the surface.And we performed the simulation calculation of CO₂ reduction reaction path to explain the CO₂electroreduction reaction mechanism of OD-Cu Zn catalyst.Therefore,our OD-Cu Zn catalyst has a broad application prospect in CO₂electroreduction to methane.