Manipulating dual effects of morphology and oxygen vacancies through the incorporation of CuO onto CeO2 nanospheres for electrochemical CO2 reduction

Despite significant advancements in the investigation of catalyst morphology in electrochemical CO2 reduction (ECR), achieving precise control over multi-carbon (C2+) products selectivity remains challenging. Thus, a sequence of catalysts with incorporation of CuO onto three-dimensional (3D) spherical CeO2 were synthesized using a hydrothermal and calcination two-step method. The molar ratios of Cu(NO3)2·H2O to Ce(NO3)3·6H2O can manipulate morphology and oxygen vacancies (Ov) of CuxCey catalysts, further influencing their product distribution in ECR. Materials characterization and electrochemical testing demonstrate that dual effects of spherical morphology and Ov in the CuxCey catalysts can enhance the activity and C2H4 selectivity in ECR. To elaborate further on the topic, the pure CeO2 exhibits excellent Faradaic efficiency (FE) of CH4 with the value of 54.3 %. Cu7Ce3, among all CuxCey catalysts, reaches a maximum value of 37.22 % at −1.2 V vs. RHE, possibly attributed to its highest Ov concentration. More significantly, the possible reaction pathway was monitor by ATR-FTIR technique for CuxCey during ECR is: CO2 → *COOH →*CO → *CHO → *OCCOH → C2H4. The concept of dual tuning strategy by morphology and Ov opens up a wide range of possibilities for the development of effective Cu-based catalysts for ECR.