二氧化碳還原反應(CO2RR)是一種具有潛力的可持續能源轉換途徑。然而，實際應用上仍面臨諸多挑戰，包括高過電位、與氫氣析出反應(HER)之間的競爭、產物選擇性以及催化劑穩定性不佳等問題。在眾多 CO2RR 產物中，多碳(C2+)產物如乙烯與乙醇因其高能量密度與重要工業價值而備受關注。 本研究中，合成了以Ag與聚乙烯吡咯烷酮(PVP)雙重修飾的Cu2O基觸媒，以提升C2+的產率。X光電子能譜(XPS)分析顯示，Ag的引入促使Cu2+含量增加，是由於電子由Cu轉移向Ag所致。進一步的非原位X光吸收光譜(XAS)分析則證實，Ag與PVP的雙重修飾顯著改變觸媒的配位環境，促進了缺陷的生成，包括Cu氧化程度增加與Cu-O配位的增強。在-1.1 VRHE條件下，Cu2O-Ag-PVP觸媒展現出最高的C2+選擇性(FEC2+ = 72.2%)與乙醇選擇性(FEC2H5OH = 52.2%)，整體表現優於未修飾的Cu2O及單一修飾的對照樣品(Cu2O-PVP與Cu2O-Ag)。長時間穩定性測試顯示，Cu2O-Ag-PVP在連續反應 12 小時期間，能維持穩定且高效的乙醇產率。此外，控制實驗進一步發現，添加叔丁醇(t-BuOH)時，乙醇產率顯著下降，且乙烯生成對質子來源具有依賴性，這些結果證實了質子供應在產物分布中的關鍵作用。原位XAS分析顯示，Cu2O-Ag-PVP 在反應過程中展現出更好的Cu價態可逆性與結構穩定性。綜合以上結果，本研究揭示了Ag與PVP在調控Cu2O 電子結構與中間體吸附行為的關鍵作用，為通過雙重修飾策略精確控制CO2RR產物選擇性提供了新的設計思路。;Carbon dioxide reduction reaction (CO2RR) is a promising route for sustainable energy conversion. However, its practical applications remain limited by high overpotential, competition from the hydrogen evolution reaction (HER), low product selectivity, and poor catalyst stability. Among the various CO2RR products, multi-carbon (C2+) products such as ethylene (C2H4) and ethanol (C2H5OH) are particularly valuable due to their high energy density and industrial relevance. In this study, Cu2O-based catalysts modified by Ag and (polyvinylpyrrolidone) PVP have been prepared to enhance C2+ production. X-ray photoelectron spectroscopy (XPS) analysis reveals that Ag incorporation increases the Cu2+ content, attributed to electron transfer from Cu to Ag. Ex-situ X-ray absorption spectroscopy (XAS) analysis further confirms that the dual modification with Ag and PVP significantly alters the coordination environment and promotes defect formation, including increased Cu oxidation and enhanced Cu-O coordination. At -1.1 VRHE, the dual-modified Cu2O-Ag-PVP catalyst shows the highest C2+ selectivity (FEC2+ = 72.2%) and ethanol selectivity (FEC2H5OH = 52.2%), outperforming unmodified Cu2O and the singly modified samples (Cu2O-PVP and Cu2O-Ag). Stability tests show that Cu2O-Ag-PVP maintains higher and more stable Faradaic efficiency for ethanol production over 12 hours. The observed suppression of ethanol formation in the presence of t-BuOH and the proton sources dependence of ethylene formation confirm the critical role of proton supply in determining product distribution. In-situ XAS shows that Cu2O-Ag-PVP exhibits improved reversibility of Cu valence-state and enhanced structural stability. This study reveals the critical role of Ag and PVP in tuning the electronic structure of Cu2O and modulating the adsorption behavior of key intermediates. These findings provide a new strategy for controlling product selectivity in CO2RR through dual catalyst modification.
