N-CQDs from reed straw enriching charge over BiO2_ x/BiOCl p-n heterojunction for improved visible-light-driven photodegradation of organic pollutants

Green bismuth-based photocatalysts have attracted extensive attention in the field of PPCPs photodegradation. The improved carrier separation efficiency still remains a key factor to enhance photocatalytic performance. Herein, N-doped biomass carbon quantum dots (N-CQDs) decorated p-n heterojunction photocatalyst BiO2_x/ BiOCl was prepared using a facile ion-etching strategy, and it displayed a markedly enhanced catalytic activity in the photodegradation of sulfonamide antibiotics. Calculated by the differential charge density, the doped NCQDs could gather photogenerated electrons, which indicated that the introduction of N-CQDs into BiO2_x/ BiOCl would effectively inhibit the recombination of photogenerated charge carriers. In addition, photocatalytic performance and density functional theory (DFT) calculation results revealed that the photogenerated electrons tended to transfer from p-BiOCl to n-BiO2_x through N-CQDs, which could generate .O(2)(- )and photogenerated h+ to oxidize the target pollutants. Benefiting from the synergistic effect of accelerated separation of e(-)-h(+) in p-n heterojunction and the electron-rich performance of N-CQDs, the superb TOC removal efficiencies (89.40% within 120 min visible-light irradiation) and toxicity reduction performance of photodegradation intermediates were achieved. As a consequence, this work will provide a design of high-quality photocatalysts and a greenpromising strategy for bismuth-based photocatalysts in the water treatment of PPCPs.

Automated summary

In this study, a p-n heterojunction photocatalyst decorated with N-CQDs showed significantly enhanced catalytic activity in the photodegradation of sulfonamide antibiotics. The introduction of N-CQDs effectively inhibited the recombination of photogenerated charge carriers, and facilitated the transfer of photogenerated electrons from p-BiOCl to n-BiO2_x, generating .O(2)(-) and photogenerated h+ to oxidize target pollutants.