Efficient photothermal conversion for oxidation removal of formaldehyde using an rGO-CeO2 modified nickel foam monolithic catalyst

Photocatalysis is a feasible method for degrading indoor formaldehyde (HCHO) pollutants. To improve the purification efficiency and lower the cost of using noble metals as the primary component of the catalyst, synergistic catalysis involving two catalytic modes, such as thermocatalysis/photocatalysis, has attracted significant attention. In this study, a monolithic catalyst was prepared by loading reduced graphene oxide (rGO) and cerium dioxide (CeO2) on a nickel foam (NF) matrix. It was observed that the HCHO removal efficiency could be > 93 % under xenon light. The pre-deposited rGO on the NF matrix served as the photothermal conversion layer and contributed to the uniform and stable loading of CeO2. The surface temperature of this synthesized monolithic catalyst could rapidly rise to 170 °C. In addition, the heat was distributed evenly because of the increased near-infrared (NIR) light absorption caused by the added rGO and high electron mobility owing to the heat-conducting property of NF. At this temperature, the oxidation of HCHO was stimulated not only by the lattice oxygen of CeO2 but also by the production of O2– via oxidation by photogenerated electrons. In addition, O2– would reoxidize Ce3+ to Ce4+ on oxygen vacancies and accelerate the lattice oxygen consumption and supply cycle to reinforce the existing Mars-van Krevelen (MvK) mechanism.