New Way for CO2 Reduction under Visible Light by a Combination of a Cu Electrode and Semiconductor Thin Film: Cu2O Conduction Type and Morphology Effect

How to take advantage of CO 2 has been one of the main issues to be addressed around the world. Although there are many methods to convert CO 2 to organic fuel, the efficiency is still not high enough for practical application. Herein, we have accomplished better conversion of CO 2 by the combination of metal electrode and semiconductor thin films responsive to visible light. First, the deposition of p-type and n-type Cu 2 O thin films onto a Cu substrate is successfully achieved. Then, the prepared Cu/Cu 2 O samples are used for catalytic reduction of CO 2 in photoelectrochemical systems in comparison with that in photochemical and electrochemical systems. The results show that CH 4 and C 2 H 4 are the major hydrocarbon gas products, and the prepared Cu/Cu 2 O samples have much higher selectivity for C 2 H 4 formation compared with the pure Cu electrode. The best yield for CO 2 reduction is obtained in the photoelectrochemical system under visible light. Additionally, CO 2 conversion efficiency over the Cu/Cu 2 O (p-type) electrode is much higher than that over Cu/Cu 2 O (n-type) with similar morphology. The morphology of Cu 2 O has an effect on the CO 2 reduction activity in the photoelectrochemical system as well. The related mechanism is discussed in detail especially for the reaction in the beginning 15 min. The study will provide us a new way to utilize solar light for efficient conversion of CO 2 into organic fuel.