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 CO 2 reduction (ECR), achieving precise control over multi-carbon (C 2+ ) products selectivity remains challenging. Thus, a sequence of catalysts with incorporation of CuO onto three-dimensional (3D) spherical CeO 2 were synthesized using a hydrothermal and calcination two-step method. The molar ratios of Cu(NO 3 ) 2 ·H 2 O to Ce(NO 3 ) 3 ·6H 2 O can manipulate morphology and oxygen vacancies (O v ) of Cu x Ce y catalysts, further influencing their product distribution in ECR . Materials characterization and electrochemical testing demonstrate that dual effects of spherical morphology and O v in the Cu x Ce y catalysts can enhance the activity and C 2 H 4 selectivity in ECR . To elaborate further on the topic, the pure CeO 2 exhibits excellent Faradaic efficiency (FE) of CH 4 with the value of 54.3 %. Cu 7 Ce 3 , among all Cu x Ce y catalysts, reaches a maximum value of 37.22 % at −1.2 V vs. RHE, possibly attributed to its highest O v concentration. More significantly, the possible reaction pathway was monitor by ATR-FTIR technique for Cu x Ce y during ECR is: CO 2  → *COOH →*CO → *CHO → *OCCOH → C 2 H 4 . The concept of dual tuning strategy by morphology and O v opens up a wide range of possibilities for the development of effective Cu-based catalysts for ECR.