In situ growth of sulfide/g-CN nano-heterostructures with an adjusted band gap toward enhanced visible photocatalysis.

In this study, the nano-heterostructures of ZnCdS (0 < x < 1) nanoparticles and small g-CN nanosheets (ZnCdS/CN) were prepared via in situ growth. Bulk g-CN was first delaminated into thin layers by an acid and alkali assisted ultrasound method. ZnCdS nanoparticles were deposited on the surface of small g-CN nanosheets in situ to fabricate ZnCdS/CN photocatalysts. The absorption band edges of the as-prepared ZnCdS/CN composites shifted to a longer wavelength region compared to g-CN. The ZnCdS/CN heterojunctions revealed super-enhanced visible-light photocatalytic activities compared to pure g-CN and ZnCdS nanoparticles. To investigate the composition dependence, the mass ratios of ZnCdS and g-CN were adjusted. ZnCdS nanoparticles (5 wt%) grown in situ on g-CN nanosheets as sample 5-ZnCdS/CN revealed a very high photocatalytic activity compared to other ZnCdS/CN and CdS/CN samples where the degradation of RhB was up to 99% within 15 min under visible light irradiation. This was ascribed to the well-matched band gap structure, large specific surface area and intimately contacted interfaces. The controllable band gap of the ZnCdS/CN composites was a key factor for their enhanced photocatalytic performance. In addition, O was the leading reactive oxidative species in this photocatalytic process in the 5-ZnCdS/CN composite system.