SnO2 quantum dots anchored on g-C3N4 for enhanced visible-light photocatalytic removal of NO and toxic NO2 inhibition

Graphitic carbon nitride (g-C3N4) has been extensively applied for NO removal due to its striking visible-light response and outstanding stability. However, the toxic NO2 product is not completely suppressed in the reaction process due to its poor photo-oxidation ability. Herein, a series of SnO2/g-C3N4 composites were successfully prepared by the decorated of SnO2 quantum dots (QDs) onto g-C3N4 sheets. The experimental results demonstrated that SnO2/g-C3N4 exhibited excellent visible-light response and enhanced photo-oxidization ability to inhibit the generation of NO2. Moreover, the heterostructure between SnO2 and g-C3N4 promotes the separation of photogenerated electron-hole pairs, which is resulted in enhanced photocatalytic NO removal performance. More importantly, the in-situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) measurement and electron spin resonance (ESR) are conducted to investigate the reaction pathway via detecting the generated intermediates, products and active radicals during NO removal process. This study provides a facile and effective method to enhance the efficiency of photocatalytic NO removal and suppress the concentration of NO2 significantly.