Ag–AgBr/g-C3N4/ZIF-8 prepared with ionic liquid as template for highly efficient photocatalytic hydrogen evolution under visible light

Constructing photocatalysts with outstanding visible light utilization efficiency and a high-efficiency photo-generated charge transfer rate is the key to the photodegradation of organic pollutants in wastewater. Oxygen-doped graphitic carbon nitride (g-C3N4) responsive to a broad visible light range was prepared, to which CdS nanoparticles (NPs) were anchored to fabricate a Z-scheme heterojunction, constructing abundant charge transport orbitals that facilitate interfacial photo-generated charge separation. Meanwhile, density functional theory (DFT) calculations and electron spin resonance (ESR) tests proved that oxygen-doped g-C3N4/CdS-3 (O-CN/CdS-3) followed the Z-scheme charge transfer mechanism. The results showed that O-CN/CdS-3 degraded 10 ppm of 2-chlorophenol (2-CP) within 60 min, with a degradation rate constant (k = 0.10832) of around 11.5-fold that of g-C3N4 (0.00945). Furthermore, the active species and main intermediate products were also studied to explore the possible degradation pathway of 2-CP. Overall, this strategy provides insight for constructing other Z-scheme heterojunction photocatalysts for the efficient degradation of CPs. 

Enhanced photocatalytic degradation of 2-chlorophenol over Z-scheme heterojunction of CdS-decorated oxygen-doped g-C3N4 under visible-light

Copper indium sulfide quantum dots in photocatalysis.

Owing to the creation of a large number of surface active sites, surface modification is an efficient strategy for improving the catalytic performances of photocatalysts. Herein, zero-dimensional (0D) p-type NiS species were developed in situ on the large surface of NiAl-LDH by controlled vulcanization. Importantly, the development of the 0D p-type NiS species not only enriched the active sites but also triggered the in situ formation of a NiS/NiAl-LDH p–n heterojunction due to NiAl-LDH, which was utterly underdeveloped in the vulcanization modification procedure. This undoubtedly accelerated the faster separation and migration of charge carriers and yielded improved photocatalytic hydrogen evolution. The optimum hydrogen production rate of the NiS/NiAl-LDH photocatalyst could reach 3408 μmol·g–1·h–1 using a 5 W LED simulation visible light, which was 52-fold that of NiAl-LDH. The design and construction of the in situ p–n heterojunction may provide a perspective for the formation of p–n heterojunction photocatalysts with a closer contact interface and highly enhanced photocatalytic activity. 

Linlin Gao

Papers

Hollow CdS nanotubes with ZIF-8 as co-catalyst for enhanced photocatalytic activity.

AgBr Nanoparticles Anchored on CdS Nanorods as Photocatalysts for H2 Evolution