Direct Z-scheme PDA-modified ZnO hierarchical microspheres with enhanced photocatalytic CO2 reduction performance

To extend the light utilization of ZnO from UV to visible light, polydopamine (PDA) was introduced. The PDAmodified ZnO hierarchical microsphere was prepared through self-assembled method taking advantage of the functional groups on dopamine. The hybridization endowed the material with better light-to-fuel harvesting efficiency, which can be ascribed to the eximious light utilization and direct Z-scheme charge transfer mechanism (DZCTM). Importantly, the DZCTM between them was confirmed by in-situ X-ray photoelectron spectroscopy (ISI-XPS) characterization. This mechanism kept the strong redox abilities of the overall photocatalyst. Besides, abundant functional groups on PDA boosted CO2 adsorption. The research highlights the feasibility of loading organic molecule on inorganic substance for photocatalytic CO2 conversion.