Assembly of S-Scheme heterojunctions In2S3/Zr-bcu-22bipy44dc and In2S3/PCN-224: Polishing band states to boost highly efficient photochemical scavenging of X-, K- and KN-types reactive dyes and Cr(VI)

Abstract

Remarkable capability in utilizing visible light and the low CB potential makes In2S3 appealing in assembling MOFs-based heterojunctions. To achieve dual-functional photocatalytic decontamination of Cr(VI) and dyes via low-energy light, the focus remains on assembly of advanced heterostructures based on water-stable Zr-MOFs and In2S3. Herein, Zr-bcu-22bipy44dc and PCN-224 were deployed to fabricate two novel heterojunctions In2S3/Zr-bcu-22bipy44dc (IS/2244) and In2S3/PCN-224 (IS/P224), respectively. Indeed, IS/2244–2 and IS/P224–2 (with 50 % mass ratio of Zr-MOFs) exhibit the optimized optical-electronic properties. The new findings confirm that IS/P224–2, assembled from visible light-sensitive PCN-224, displays higher photocatalytic REDOX abilities than IS/2244–2 in degrading X-, K- and KN-types reactive dyes (RR2, RB13 and RB21) and reducing Cr2O72- ions. The elimination efficiencies of IS/P224–2 towards RR2, RB13, RB21 and Cr(VI) have reached 93.9 %, 95.8 %, 89.4 % and 98.0 % under 500 W xenon lamp, providing accelerated kinetic rates of 7.32, 14.04, 40.2 and 23.67 times of PCN-224, 112.8, 19.95, 10.58 and 3.38 times of In2S3, 5.04, 1.02, 1.39 and 1.78 times of IS/2244–2, respectively, which have been well maintained even after four photocatalytic cycles. More prominently, its performance has surpassed that of some reported MOFs-based materials and other photocatalysts. Mechanism studies have confirmed the potential active radical species, carriers transfer path and S-Scheme talents of two heterojunction materials. This study offers a feasible avenue to design low-energy light-driven bifunctional photocatalysts for water environment remediation.