High efficiency photothermal synergistic degradation of toluene achieved through the utilization of a nickel foam loaded Pt-CeO2 monolithic catalyst

Abstract

Recent research highlights the pressing need for innovative and practical oxidation degradation technologies for volatile organic compounds (VOCs). In this study, a monolithic catalyst was successfully developed by loading Pt-CeO2 onto nickel foam (NF) matrix through hydrothermal and reduction methods. The photothermal catalytic performance was investigated at room temperature for varying Pt content, toluene concentration, light source type, and water content. Remarkably, the toluene removal efficiency and CO2 selectivity stabilized at 98.8 % and 74.6 %, respectively, within less than 10 min of light activation. The d-d transition thermal effect of CeO2 and plasma effect of Pt enhanced light-to-heat conversion and active free radical generation (•O2– and •OH) through light absorption, respectively. The NF matrix's excellent thermal conductivity ensured a rapid increase in catalyst temperature upon visible light irradiation, reaching 173 °C. The study demonstrated that both the Mars-van Krevelen (Mvk) oxidation process, driven by temperature increase from near-infrared (NIR) absorption, and the free radical oxidation process, induced by higher energy illumination, synergistically contributed to toluene decomposition and mineralization. The catalyst's morphology, physical and chemical properties, surface synergistic oxidation process involving gaseous oxygen and free radicals, and toluene degradation pathway were thoroughly analyzed. We believe that this coexistence of thermocatalytic and photocatalytic mechanisms in a monolithic catalyst driven by renewable solar energy holds significant potential for practical applications and warrants further exploration.