Cellulose template designed porous ZnO based catalysts with different valence copper for solar photocatalytic CO2 conversion

Designing a green method to enhance the utilization of photocatalysts on solar energy was of great significance to alleviate energy problems. The porous ZnO-based catalysts with different valence copper (CuO−ZnO Cel-T and Cu−ZnO Cel-T ) were successfully obtained by using cellulose fibers as templates, which possessed three-dimensional structures and excellent photocatalytic activities. The dispersibility of CuO−ZnO Cel-T nanoparticle was influenced by surface groups of cellulose template, the more active sites of composite catalyst were exposed than CuO−ZnO catalysts with carbon fiber as the template and CuO−ZnO powders without any template. Moreover, to explore the effects of different valence states of Cu on the photocatalytic activity of ZnO nanoparticles, wheat straw was used to reduce CuO−ZnO Cel-T to Cu−ZnO Cel-T by using pyrolysis reduction treatment of wheat straw. The CO production rate of Cu−ZnO Cel-T (30.17 µmol*g −1 h −1 ) was significantly higher than CuO−ZnO Cel-T (8.61 µmol*g −1 h −1 ) based on the same catalyst morphologies, indicating that the surface plasmon resonance (SPR) effect of Cu was more favorable for improving catalytic activities of ZnO than the structure effect of CuO−ZnO Cel-T heterojunction. This work proposed an exciting idea for using biomass materials to tailor the photocatalytic performance of catalysts and reduce copper ions in a cleaner method. • Fibriform CuO−ZnO and Cu−ZnO catalysts were prepared using cellulose as template. • Cellulose fiber templates can disperse and immobilize catalyst nanoparticles well. • Wheat straw was introduced as a reducing agent to reduce Cu 2+ to Cu 0 . • CuO−ZnO and Cu−ZnO catalysts both exhibited excellent photocatalytic activities. • Cu enhancement for photocatalytic activity of ZnO was better than that of CuO.