Photoelectrochemical CO2 reduction to syngas by a ZnO–CdS–Cu nanocomposite

Abstract Syngas, the mixture of CO and H2, is an important feedstock for producing methanol and other liquid fuels. Herein, we demonstrated a photoelectrochemical system by employing cadmium sulfide (CdS)-decorated zinc oxide (ZnO) nanoparticles and Cu nanorods to boost the photoelectrochemical reduction of carbon dioxide (CO2) in an aqueous solution. Structural characterizations showed that the heterostructure and interfaces of semiconductors facilitated the photo-absorption as well as the fast transfer of photogenerated carriers from the semiconductors to catalytic sites. Compared to the condition with light off, the tri-component ZnO–CdS–Cu catalyst exhibited an enhancement of 6.2 times in the CO partial current density at relatively low applied potential of –1.16 V versus reversible hydrogen electrode under ∼1 sun illumination. In addition, the ratio of CO and H2 in the products was tuned in a wide range between 0.03 and 0.53, which was beneficial for the syngas production.