Defects and internal electric fields synergistically optimized g-C3N4-x/BiOCl/WO2.92 heterojunction for photocatalytic NO deep oxidation.

In this work, g-C3N4-x/BiOCl/WO2.92 heterojunction with "N-O" vacancies was prepared using NaBiO3 and WCl6 as raw materials and non-metal plasma of WO2.92 grew in-situ on the surface of BiOCl, resulting in the enhanced photocatalytic NO deep oxidation. XPS tests and DFT calculation indicated the formation of internal electric fields from g-C3N4-x to BiOCl, BiOCl to WO2.92, which induced the transition from Ⅱ-Ⅱ-type to double Z-scheme hetero-structure. High separation efficiency, prolong lifetime and strong redox ability of photo-generated electron-hole pairs were simultaneously achieved due to the charge capture effect of defects and double Z-scheme mechanism. Therefore, g-C3N4-x/BiOCl/WO2.92 exhibited the significantly increased NO removal rates from 21.17% (BiOCl/WO2.92) and 36.52% (g-C3N4-x) to 68.70% and the main oxidation product of NO was NO3-. This study revealed that the carrier dynamics of heterojunction photocatalysts could be optimized by the synergistic effect of defects and internal electric fields to achieve photocatalytic NO deep oxidization.