Efficient CO2 reduction to C2 products in a Ce-TiO2 photoanode-driven photoelectrocatalysis system using a Bnanometer Cu2O cathode

Abstract

Excessive emission of CO2 into the atmosphere has caused significant environmental issues. Photoelectrocatalytic (PEC) reduction of CO2 is an effective method that combines the benefits of both photo- and electrocatalysis. This process effectively minimizes CO2 emissions, enhances the efficiency of CO2 reduction, and diminishes energy consumption during the reduction process. In this work, we have successfully developed a photoelectrochemical (PEC) system, integrating a Ce-doped TiO2 film as the photoanode and Cu2O as the dark cathode, in which the 4% Ce-TiO2 film photoanode demonstrated the best performance. Electrochemical performance data revealed that the Cu2O catalysts, characterized by their octahedral geometry that optimally presents active sites for CO2 reduction, displayed superior activity in converting CO2. Through a straightforward hydrothermal synthesis, we crafted three-dimensional, flower-like TiO2 thin films. The strategic incorporation of cerium into the TiO2 matrix not only enhanced the material's crystallinity but also resulted in a uniform and compact morphology. This modification significantly narrowed the band gap of TiO2, thereby boosting its photocatalytic capabilities. In the system where a 4% Ce-TiO2 thin film photoanode was used to drive the PEC reduction of CO2, the octahedral Cu2O catalyst demonstrated the highest selectivity for C2 products. This occurred at a reaction voltage of −1.4V vs. RHE, resulting in a total Faraday efficiency of 67.33%. Notably, this Faraday efficiency is double the one produced from the electrocatalytic (EC) system. This work demonstrates that the use of a 4% Ce-TiO2 film as a photoanode is able to solve the photocorrosion problem of the Cu2O catalyst while employing a photovoltaic combination to enhance the selectivity to C2 products.