MoS₂ Quantum Dot Growth Induced by S Vacancies in a ZnIn₂S₄ Monolayer: Atomic-Level Heterostructure for Photocatalytic Hydrogen Production

Abstract

It is highly demanded to steer the charge flow in photocatalysts for efficient photocatalytic hydrogen reactions (PHRs). In this study, we developed a smart strategy to position MoS quantum dots (QDs) at the S vacancies on a Zn facet in monolayered ZnInS (Vs-M-ZnInS) to craft a two-dimensional (2D) atomic-level heterostructure (MoSQDs@Vs-M-ZnInS). The electronic structure calculations indicated that the positive charge density of the Zn atom around the sulfur vacancy (Vs) was more intensive than other Zn atoms. The Vs confined in monolayered ZnInS established an important link between the electronic manipulation and activities of ZnInS. The Vs acted as electron traps, prevented vertical transmission of electrons, and enriched electrons onto the Zn facet. The Vs-induced atomic-level heterostructure sewed up vacancy structures of Vs-M-ZnInS, resulting in a highly efficient interface with low edge contact resistance. Photogenerated electrons could quickly migrate to MoSQDs through the intimate Zn-S bond interfaces. As a result, MoSQDs@Vs-M-ZnInS showed a high PHR activity of 6.884 mmol g h, which was 11 times higher than 0.623 mmol g h for bulk ZnInS, and the apparent quantum efficiency reached as high as 63.87% (420 nm). This work provides a prototype material for looking into the role of vacancies between electronic structures and activities in 2D photocatalytic materials and gives insights into PHR systems at the atomic level.

Ion Sputtering–Assisted Double‐Side Interfacial Engineering for CdIn2S4 Photoanode toward Improved Photoelectrochemical Water Splitting

“…In Figure e, the presence of Ni peaks at 872.9 and 855.4 eV represents the characteristic signal of Ni 2+ in NiO. After coating with NiO, the peaks of Cd 2+ , In 3+ , and S 2− shift to lower binding energy, indicating that electrons transport from NiO to CdIn 2 S 4 . Meanwhile, the positive shift of the peaks of Ni 2+ and O 2− indicates that holes transport from CdIn 2 S 4 to NiO.…”

Defect Engineering of Photocatalysts for Solar Energy Conversion

“…The defects could be introduced into the semiconductors by plasma etching as a promising strategy . For example, as‐synthesized In 2 O 3− x /In 2 S 3 layers with OVs were fabricated by plasma treatment (Figure ).…”

“…Oxygen‐ vacancies‐confined in TiO 2 crystals were produced through Ar plasma etching strategy, enhancing charge separation and promoting PC performance of water splitting . Moreover, the defects could also be introduced into the nanomaterials through a liquid‐ammonia‐assisted lithiation strategy . For example, sulfur‐vacancies‐confined in ZnIn 2 S 4 (V s ‐ZnIn 2 S 4 ) nanosheets were fabricated through a lithiation‐chemistry approach (Figure ), manipulating the electronic structure and the PC performance of defective ZnIn 2 S 4 nanosheets.…”

“…For example, sulfur‐vacancies‐confined in ZnIn 2 S 4 (V s ‐ZnIn 2 S 4 ) nanosheets were fabricated through a lithiation‐chemistry approach (Figure ), manipulating the electronic structure and the PC performance of defective ZnIn 2 S 4 nanosheets. To promote the charge separation of ZnIn 2 S 4 , the high PC hydrogen generation rates, 6.884 and 11.9 mmol g −1 h −1 , were achieved using as‐synthesized hybrids of MoS 2 quantum dots/V s ‐ZnIn 2 S 4 and Z‐scheme NiS/WO 3 /V s ‐ZnIn 2 S 4 heterostructures due to the introduction of the defect and the construction of the heterostructure . Meanwhile, hydrogenated ZnIn 2 S 4 with the defects using UV irradiation presented the wide spectrum responsive photocatalysis .…”

“…Copyright 2019, Elsevier Ltd. b) Schematic synthesis of MoS 2 @V s ‐M‐ZnIn 2 S 4 heterostructures. Reproduced with permission . Copyright 2018, American Chemical Society.…”