Key role of light in highly efficient photothermocatalytic steam cellulose reforming on Co/CeO2–Al1Mg3O4.5

Abstract

Photothermocatalysis provides an effective approach to sustainably produce renewable fuels by utilizing the energy of the whole solar spectrum. Here, merely with focused solar spectrum illumination, highly efficient photothermocatalytic steam cellulose reforming is achieved on Co/CeO₂–Al₁Mg₃O_4.5. The catalyst exhibits extremely high H₂ and CO production rates (3374.4 and 1872.1 mmol g_catalyst⁻¹ h⁻¹) along with a 7.8% light-to-fuel efficiency, attributed to the light-driven thermocatalytic process on Co nanoparticles that utterly differs from traditional photocatalysis. The undesired tar mainly produced by cellulose pyrolysis is substantially reduced by the reaction of H₂O with carbon-containing species. The active lattice oxygen (O_lattice) of CeO₂ is involved in the reaction by transferring to the surface of Co nanoparticles (Co NPs) loaded on the CeO₂. The oxygen vacancies left on the surface of CeO₂ nanoparticles can subsequently be replenished by oxygen from H₂O dissociation, thus substantially enhancing the reaction of H₂O with carbon-containing species, which is key to improving catalytic activity and reducing undesired tar yield. In addition to being the single heating source, the illumination exhibits a significant photoactivation effect on promoting the O_lattice of CeO₂, and surface oxygen species of Co NPs to react with the carbon-containing species, thus considerably facilitating the reaction of H₂O with carbon-containing species.