CO2-to-Methanol Photo-Hydrogenation on CuO/ZnO cluster catalyst/metal organic framework composites in chitosan film☆

Both copper and zinc ions in water without oxidizer and protector were oxidized to metal oxide clusters by irradiating femtosecond pulse laser for one minute at room temperature. CuO was embedded inside ZIF-8 metal organic framework, while ZnO covered the CuO-embedded ZIF-8 nanoparticles. Chitosan was used as the adsorption site of CO2 gas and the embedding host of metal oxides/ZIF-8 composites. The photocatalytic reaction was conducted using UV-light, and the evaluated methanol production depended on the catalyst loading and reached to 10.6 mmol/g(catalyst). The result indicates that the ZIF-8-hosted nanocomposite-chitosan film exhibit the effective photocatalytic performance for the conversion of greenhouse CO2 gas to methanol. Then ZIF-8 condenses the catalysts in and on ZIF-8, chitosan surrounding the catalyst-holding ZIF-8 adsorbs CO2 gas to facilitate the photoreaction by neighboring catalysts, and cluster-sized semiconductors exert their photocatalytic activity with a merit having the large surface area resulting from their small size (similar to 1 nm). Thus, this research demonstrates the advantage of metal oxide quantum dot clusters, which were prepared by the innovative physical bottom-up synthesis based on the femtosecond pulse light source.