Photocatalytic conversion of gaseous carbon dioxide to methanol on CuO/ZnO-embedded carbohydrate polymer films

A procedure that diminishes carbon dioxide in the atmosphere and converts it to alternative biofuels was reported. On zinc oxide (ZnO) nanoparticles synthesized in ethandiol, copper oxide (CuO) nanoclusters were deposited by femtosecond pulsed-laser irradiation. CuO-deposited ZnO was chemically bound with amine-terminated poly(amido amine) dendrimer using 3-glycidyloxypropyltrimethoxysilan, mixed with TEMPO-oxidized cellulose nanofibril, and molded to a film (CuO/ZnO-Den-TOCNF film). CuO/ZnO was also embedded in a chitosan (CS) matrix and molded to a film. Both films were used for adsorption and conversion of gaseous carbon dioxide. The amine groups in dendrimer loaded on TOCNF and in CS act as adsorption sites of carbon dioxide, and CuO/ZnO is a photocatalyst. On photocatalytic conversion, a composite film converted gaseous carbon dioxide to methanol (maximum 2.42 and 2.16 mmol/g(catalyst) on CuO/ZnO-Den-TOCNF and CuO/ZnO-CS films, respectively) and produced less acetaldehyde (0.030 and 0.037 mmol/g(catalyst), respectively) on irradiation with ultraviolet light for 6 h. The results indicate that the amine group is the vital component to adsorb carbon dioxide besides the catalyst (CuO/ZnO) for the conversion of carbon dioxide. Moreover, TOCNF and CS-based catalytic films are preferable with the objectives of easily removable systems from reaction vessels and of convenient environmentally compatible resources.