Efficient Solar Light Harvesting CdS/Co₉S₈ Hollow Cubes for Z‐Scheme Photocatalytic Water Splitting

Abstract

Hollow structures with an efficient light harvesting and tunable interior component offer great advantages for constructing a Z‐scheme system. Controlled design of hollow cobalt sulfide (Co9S8) cubes embedded with cadmium sulfide quantum dots (QDs) is described, using hollow Co(OH)2 as the template and a one‐pot hydrothermal strategy. The hollow CdS/Co9S8 cubes utilize multiple reflections of light in the cubic structure to achieve enhanced photocatalytic activity. Importantly, the photoexcited charge carriers can be effectively separated by the construction of a redox‐mediator‐free Z‐scheme system. The hydrogen evolution rate over hollow CdS/Co9S8 is 134 and 9.1 times higher than that of pure hollow Co9S8 and CdS QDs under simulated solar light irradiation, respectively. Moreover, this is the first report describing construction of a hollow Co9S8 based Z‐scheme system for photocatalytic water splitting, which gives full play to the advantages of light‐harvesting and charges separation.

Hollow Nanostructures for Photocatalysis: Advantages and Challenges

“…The Z‐scheme largely relaxes the bandgap requirement of semiconductors, resulting in an expansion of candidates for various photocatalytic reactions. [20b,52] Very recently, the combination of Z‐scheme and hollow nanostructures composed of Co 9 S 8 and CdS was reported to achieve much better photocatalytic H 2 evolution performance compared with that of the solid counterpart (Figure c,d) . However, the mechanism understanding of the Z‐scheme system is still not fully understood and continuous efforts are required to achieve more efficient solar‐energy‐conversion systems.…”

“…d) Time course of photocatalytic H 2 evolution under light irradiation over different samples. Reproduced with permission . Copyright 2017, Wiley‐VCH.…”

“…For instance, a TiO 2 /CdS double‐shell heterojunction was obtained by a two‐step coating process with SiO 2 spheres as a hard template . In addition, Co 9 S 8 /CdS hollow cubes have been designed based on a multistep process (Figure b) . First, Co(OH) 2 hollow cubes were prepared with the Cu 2 O as the hard template.…”

Recent Advances in First‐Row Transition Metal Clusters for Photocatalytic Water Splitting

“…[107] Color Code: Fe, green; Sb, black; O, red. materials, [125] and modifying the morphologies [126] were developed to overcome the abovementioned problems.…”

Recent Advances of Ternary Layered Cu2MX4 (M = Mo, W; X = S, Se) Nanomaterials for Photocatalysis

“…Finally, the photocatalytic process occurs with the dye degradation or water molecules splitting on the surface of photocatalysts . So far, modifying traditional photocatalysts (e.g., TiO 2 , CdS, and BiWO 6 ) for enhanced activity or developing new type of photocatalysts (e.g., sulfides, oxides, and nitrides) have been regarded as two competitive strategies to meet the demand for solving energy and environmental problems. Among various new materials, layered Cu 2 MX 4 (M = Mo, W; X = S, Se), which is an important ternary transition metal chalcogenide (TTMC), has attracted much attention due to the outstanding properties with adjustable component, variable structure, diversified morphology, and unique electronic structure.…”