Based on interface effects and structural optimization, the properties of SiO2 and layered double hydroxides (LDHs) material were integrated to prepare SiO2/CoMnFeOx composites for denitration technology. The optimum SiO2(0.5)/Co0.5Mn1.5Fe1Ox catalyst had excellent NOx conversion (>90%) and N2 selectivity (>80%) at 150-250°C. In addition, the stability of SiO2(0.5)/Co0.5Mn1.5Fe1Ox against SO2 and H2O was much higher than that of Co0.5Mn1.5Fe1Ox (14~20%) and Co-Mn-Fe/SiO2 (56~61%) operating at 200°C for 30 h. The enhanced N2 selectivity of SiO2(0.5)/Co0.5Mn1.5Fe1Ox catalyst was achieved by inhibiting the formation of N2O by-products through “NOx + NH3 + O2” pathway. The abundant surface adsorbed oxygen and active species, appropriate surface acid and redox ability promoted the NH3-SCR reaction of SiO2(0.5)/Co0.5Mn1.5Fe1Ox catalyst. In situ DRIFTS analysis and density functional theory (DFT) calculations were conducted to discuss the adsorption/activation of reactive species, reaction pathways, and mechanism of resistance to SO2 and H2O poisoning. This work provided a new strategy for the development of low-medium temperature NH3-SCR catalysts with excellent resistance to SO2 and H2O.

Photocatalytic processes driven by visible-light irradiation offer a sustainable means of micropollutants removal from aquatic environments without the addition of reagents. In this study, an enhanced production of photogenerated carriers under visible light has been achieved using acidified graphitic carbon nitride (ag-C3N4) modified with atomically-dispersed Cu (Cu/ag-C3N4), which serves as an efficient photocatalyst for treating mi/’cropollutants. The optimized Cu/ag-C3N4 system achieved greater than 90% micropollutants removal efficiency within 30 min. A combination of experimental testing and density functional theory analysis has confirmed the formation of an active and stable CuN3 configuration, generated by the incorporation of atomic Cu species at C vacancies that effectively modulates surface charge redistribution and enables charge separation. The photocatalytic degradation of micropollutants is promoted by photogenerated holes (h+) in tandem with reactive oxygen species (·OH, O2¯·, 1O2), where O2¯· and 1O2 species play dominant roles in the Cu/ag-C3N4 system. The application of ultra-performance liquid chromatography-tandem mass spectrometry analysis has been used to identify possible degradation pathways and establish a synergistic degradation mechanism. This work provides a comprehensive understanding of heteroatom doping that enhances photocatalytic activity, offering a new strategy in designing highly efficient photocatalysts for treating micropolluted water.