Palygorskite Immobilized Direct Z-Scheme Nitrogen-Doped Carbon Quantum dots/PrFeO3 for Photo-SCR Removal of NOx

Photocatalysis-selective catalytic reduction (photo-SCR) of NOx is recognized as a potential approach for the abatement of nitrogen oxides. However, the development of an efficient photocatalyst for photo-SCR is strongly desired. In the current work, nitrogen-doped carbon quantum dots (N-CQDs)-modified PrFeO3/palygorskite (Pal) was prepared by a sol-gel/impregnation method. Results indicate that Pal nanorod not only exhibits excellent adsorption performance for gas molecules but also behaves as an ideal support for the immobilization of perovskite particles, leading to enhanced charge separation and visible light absorption facilitated by the formation of Z-scheme heterostructure of N-CQDs/PrFeO3, as revealed by the photoluminescence spectra and Mott-Schottky characterizations. The influence of the mass fraction of N-CQDs relative to PrFeO3 (from 1 to 9 wt %) on the NOx conversion and N-2 selectivity was investigated under visible light irradiation. The 5 wt % N-CQDs/PrFeO3/Pal is found to display the highest efficiency of 93% and 100% N-2 selectivity favored by abundant acid sites and excellent reducibility, as indicated in NH3-TPD and H-2-TPR measurements. Additionally, the tolerance to SO2 and H2O shows no obvious deactivation due to the fact that N-CQDs and Pal can benefit the adsorption of SO2 and H2O and prevent NH3 from being sulfated by SO2 and the catalyst from being eroded by H2O, respectively.