Organic ligand-engineered MOFs-derived spinel CoMn2O4 with tailored nanostructures and chemical properties for synergistic low-temperature removal of NOx and VOCs.

Synchronous abatement of NOx and VOCs is essential for mitigating ozone and PM2.5 pollution, yet balancing NH3-SCR and VOCs oxidation concurrently at low temperature remains challenging. Herein, an organic ligand-oriented strategy was used to modulate nanostructure and chemistry properties of MOFs-derived spinel CoMn2O4 by carboxylate-based MIL-101 and imidazolate-based ZIF as precursors, achieving low-temperature synergistic removal of NO and toluene. CoMn/ZIF shows a porous, sheet-like morphology characterized by stacked nanosheets forming an open, interconnected framework. This structure facilitates active site exposure while mitigating nanoparticle agglomeration. Additionally, N-doped carbon matrix derived from ZIF introduces abundant oxygen vacancies and unsaturated metal sites, enriching weak-to-medium acid sites and promoting redox cycling. In contrast, CoMn/MIL-101 presents densely packed agglomerates due to structural collapse, exhibiting primarily strong acid sites with limited redox capability. Overall, CoMn/ZIF exhibits superior low-temperature catalytic activity with over 90.84 % NO conversion and the lowest T90 of 207 °C for toluene oxidation at 150-275 °C, surpassing CoMn and CoMn/MIL-101. Furthermore, NH3-SCR on CoMn/ZIF promotes the generation of reactive oxygen species by sustaining redox cycling and localized oxidative environments, while sustained NH3 consumption reduces competitive adsorption with toluene. This study provides guidance for designing multifunctional catalysts via MOFs-ligand engineering, aiming at low-temperature integrated purification systems.