Design Principles and Structure-Activity Relationships of Single-Atom Catalysts for Low-Temperature VOCs Oxidation and Related Probe Reactions

Volatile organic compounds (VOCs) are key precursors of ozone and secondary organic aerosols and pose serious risks to human health. Consequently, stringent emission abatement is urgently required under realistic operating conditions such as low inlet concentrations, high gas hourly space velocities, and high humidity. Catalytic oxidation is widely regarded as one of the most competitive end-of-pipe technologies. However, low-temperature operation remains kinetically challenging. Oxygen activation is sluggish, reaction intermediates can bind strongly, and catalysts are prone to deactivation by water, chlorine/sulfur-containing species, and carbonaceous deposits. Single-atom catalysts (SACs) provide an atomic-level platform in which isolated metal centers exhibit unique electronic structures and metal–support interfacial chemistry. These features can fundamentally reshape oxygen activation and VOC oxidation pathways. This review summarizes recent advances in SACs for low-temperature VOC oxidation and discusses how anchoring motifs (M–Ox, M–Nx, and defect-localized sites), support redox properties, and microenvironmental factors (hydroxyls and hydrophilicity) synergistically regulate oxygen delivery (adsorbed oxygen vs lattice oxygen), intermediate evolution (formate/benzoate/carbonate species), and conversion stability. Finally, perspectives are provided on future design and application of single-atom catalysts.