Heterojunction of CdS Nanocapsules–WO₃ Nanosheets Composite as a Stable and Efficient Photocatalyst for Hydrogen Evolution

Abstract

CdS based nanocomposites are well reported for photocatalytic hydrogen evolution reactions because of their favorable band edge potentials. The preparation of well dispersed photocatalyst plays an important role in the enhancement of H2 production efficiency. Among all the other morphologies of CdS, nanorods gained considerable attention due to their channeled charge carrying ability and improved surface area. Herein, CdS nanocapsules, which offer short and extensive charge carrier transport and enlarged surface area, were synthesized via the solvothermal method. Poly­(vinyl pyrrolidine) was used as a capping agent for size control and better dispersion. Tungsten oxide nanosheets were synthesized via the hydrothermal route, and CdS nanocapsules were incorporated on the tungsten oxide nanosheets via the wet impregnation method. Photocatalytic hydrogen generation under solar light and simulated solar light irradiations with lactic acid as a sacrificial agent employing the prepared nanocomposite gave impressive and enhanced results, and furthermore the catayst was efficient and stable. The optimized photocatalyst showed a hydrogen production rate of about 146.2 mmol.h–1 .g–1 cat. This is the highest rate reported yet for the combination of CdS and WO3.The Z-scheme heterojunction formation between two different morphologies plays a key role in the enhancement of H2 generation.

Role of Ti3C2 MXene as Prominent Schottky Barriers in Driving Hydrogen Production through Photoinduced Water Splitting: A Comprehensive Review

“…The major constraint in the application of CdS as a photocatalyst is that they are typically subjected to photocorrosion. 84 It is indisputable that the low rate of hydrogen generation is indicatively caused by the low chemical stability of the photocatalyst, generally due to photocorrosion. Besides, the charge recombination in bulk CdS is considerably higher, restraining their functionality and applicability in largescale photocatalytic hydrogen production.…”

“…It is noted that CdS has appropriate band potential and a narrow bandgap of 2.4 eV, which are considered to be features of a good visible-active photocatalyst. The major constraint in the application of CdS as a photocatalyst is that they are typically subjected to photocorrosion . It is indisputable that the low rate of hydrogen generation is indicatively caused by the low chemical stability of the photocatalyst, generally due to photocorrosion.…”

Photocatalytic degradation and mineralization of dye pollutants from wastewater under visible light using synthetic CuO-VO2/TiO2 nanotubes/nanosheets

“…The results match the XRD pattern, XPS, and element distribution map analysis. It is well documented that long narrow channels play an important role in electron transferring, light conversion, and enhanced ion diffusion at the semiconductor interface from tubular depth and tube wall [50][51][52][53][54].…”

Ultrathin tungsten-doped hydrogenated titanium dioxide nanosheets for solar-driven hydrogen evolution

“…3 To date, a variety of semiconductor-based photocatalysts have been widely used for photocatalytic hydrogen production by water splitting, such as Fe 2 O 3 , WO 3 , Cu 2 O, TiO 2 , and CdS. [4][5][6][7] Among them, titanium dioxide (TiO 2 ) is famous for its abundance and stable photochemical performance. 8,9 However, TiO 2 with a large bandgap of about 3.2 eV can only absorb ultraviolet light, which accounts for less than 5% of the total solar spectrum.…”