Confined Catalysts Application in Environmental Catalysis: Current Research Progress and Future Prospects

Abstract Space‐confined catalysis can help create unique nanoscale chemical environments partitioned from the surrounding bulk space and has become a feasible strategy for designing high‐efficiency catalysts for various reactions. Confinement effects can affect both the reacting molecules and confined metal/metal‐oxide nanoparticles. This review mainly documents the progress in the design and applications of confined catalysts used in environmental catalysis (selective catalytic reduction (SCR) of NO x with ammonia, catalytic oxidation of CO and volatile organic compounds (VOCs), photocatalytic oxidation of VOCs, and photocatalytic CO 2 reduction). Throughout the review, the impact of confinement effects on the activity, selectivity, and stability of catalysts is emphasised. Materials such as carbon nanotubes (CNTs), titanate nanotubes (TNTs), zeolites, mesoporous TiO 2 , and metal−organic frameworks (MOFs) are common confined hosts. In the NH 3 ‐SCR reaction, confined catalysts, which are non‐noble metals confined in titanate/carbon nanotubes catalysts, have been widely studied. The protection offered by the confined space can shield metal/metal‐oxide nanoparticles from toxic components (e. g., SO 2 , alkali metals, and heavy metals), while improving the activity of the catalysts. In the field of catalytic oxidation of CO and VOCs, noble metals are always confined in the host without aggregating, sintering, or poisoning and show enhanced activity. In the photocatalytic oxidation of VOCs and photocatalytic reduction of CO 2 , the application of confined catalysts can prolong the contact time of reactants and improve visible‐light absorption and electron transfer, leading to better catalytic performance.