Construction of Highly Dispersed Ni Sites on N-rich Carbon Nitride for Enhanced Photocatalytic NO Removal

Intelligent active site engineering to harness photogenerated charge carriers and motivate surface reactions is at the core of catalysis. Herein, highly dispersed Ni sites are planted on C3N5, an N-rich carbon nitride, by a facial two-step annealing method to construct a Ni-C3N5 material. The incorporation of Ni sites can significantly enhance the e(-)/h(+) separation efficiency of C3N5 under light irradiation and promote the activation of O-2 to produce reactive oxygen species. Compared with pristine C3N5 (with NO removal ratio of approximate to 35%), the as-prepared 0.1- or 0.25-Ni-C3N5 material can remove approximate to 54% continuous-flowing NO (initial concentration: 600 ppb) quickly in less than 25 min under white LED light irradiation. The long-term photocatalytic performance demonstrates that the catalyst is stable without obvious attenuation in activity. The findings of the trapping experiments and in situ diffuse reflectance infrared fourier transform spectroscopy tests suggest that O-center dot(2)- may mainly convert NO into NO2, while (OH)-O-center dot and O-1(2) play a significant role in the NO2 to NO3- conversion reaction. The present work brings new insights into the design of active sites on semiconductor photocatalytic materials for the treatment of NOx species.