Light-assisted ethanol dry reforming over NiZnOx hollow microspheres with enhanced activity and stability

Light-assisted thermocatalytic dry reforming of ethanol (EDR) utilizing the synergistic effect of photocatalysis and thermocatalysis is regarded as a promising route to convert greenhouse gas CO2 into value-added chemicals. In this work, double-shell NiZnOx hollow microspheres (NiZnOx-M) were synthesized as light-harvesting catalyst to enhance EDR performance under mild conditions. The characterization results of UV-vis-NIR and Photoluminescence Spectroscopy (PL) indicated that the band gap energy of NiZnOx-M catalyst was narrower because of the smaller Ni nanoparticles, thereby broadening its optical response range especially in visible light. The strong absorbance of light could greatly improve the activation of ethanol/CO2 and the gasification of carbon. With light irradiation, light could induce the transfer of photogenerated electron from semiconductor ZnO to active metal Ni, reducing the reaction energy barrier. Hence, NiZnOx-M catalyst showed superior photothermal catalytic activity along with good resistance capacity to coke accumulation and aggregation of active metal. Ethanol conversion was ca.2 times those obtained over NiZnOx-C prepared by conventional precipitation method. No obvious deactivation occurred after 100 h tests. This work provides some guidance for the design of high-performance photothermal catalyst to achieve the photo-thermal-chemical conversion of the greenhouse gases.