Construction of efficient g-C3N4/NH2-UiO-66 (Zr) heterojunction photocatalysts for wastewater purification

Herein, g-C3N4/NH2-UiO-66 (Zr) heterojunction photocatalysts were successfully constructed by a solvothermal and in-situ deposition route. It presented high-efficiency photocatalytic hexavalent chromium (Cr (VI)) removal activity and promoted photocatalytic Cr (VI) reduction and tetracycline hydrochloride (TC-HCl) oxidation synergistically. The experimental and theoretical analysis confirmed that the photocatalytic removal efficiency of Cr (VI) by CU-20 wt.% forming heterojunction structure was 1.86 times that of pure NH2-UiO-66 (Zr) under visible light irradiation, and prepared photocatalysts exhibited significant stability and good repeatability. Simultaneously, the effects of different influencing factors such as the concentration of Cr (VI) and different pH values on the photocatalytic performance of CU-20 wt.% were clarified. Moreover, CU-20 wt.% could synergistically remove pollutants in the mixed solution system, and the efficiency of Cr (VI) reduction reached 100% within 90 min under visible light irradiation, and improved the efficiency of TC-HCl oxidation. A heterojunction structure constructed can effectively enhance the separation and transfer of carriers and synergistic effect, and furtherly improve the photocatalytic performance. This work proposes that photocatalysts with heterojunction structures would be effectively applied to wastewater purification.