Hierarchically CdS Decorated 1D ZnO Nanorods‐2D Graphene Hybrids: Low Temperature Synthesis and Enhanced Photocatalytic Performance

Abstract

A simple, low‐temperature synthesis approach is reported for planting CdS‐sensitized 1D ZnO nanorod arrays on the 2D graphene (GR) sheet to obtain the ternary hierarchical nanostructures, during which graphene oxide (GO) as the precursor of GR acts as a flexible substrate for the formation of ZnO nanorod arrays. The hierarchical CdS‐1D ZnO‐2D GR hybrids can serve as an efficient visible‐light‐driven photocatalyst for selective organic transformations. The fast electron transport of 1D ZnO nanorods, the well‐known electronic conductivity of 2D GR, the intense visible‐light absorption of CdS, the unique hierarchical structure, and the matched energy levels of CdS, ZnO and GR efficiently boost the photogenerated charge carriers separation and transfer across the interfacial domain of hierarchical CdS‐1D ZnO‐2D GR hybrids under visible light irradiation via three‐level electron transfer process. Furthermore, the superior reusability of ternary hybrids is achieved by controlling the reaction parameters, i.e., using visible light irradiation and holes scavenger to prevent ZnO and CdS from photocorrosion. This work demonstrates a facile way of fabricating hierarchical CdS‐1D ZnO‐2D GR hybrids in a controlled manner and highlights a promising scope of adopting integrative photosensitization and co‐catalyst strategy to design more efficient semiconductor‐based composite photocatalysts toward solar energy capture and conversion.

A Review on the Fabrication of Hierarchical ZnO Nanostructures for Photocatalysis Application

“…For example, nanoscale tree-like CdS/ZnO nanocomposites with a hierarchical architecture showed the ability for selective oxidation of thioanisole and anaerobic reduction of nitro compound 4-nitroaniline under irradiation of artificial solar light [108]. In addition, hierarchical CdS-decorated 1D ZnO nanorod-2D graphene hybrids exhibit enhanced photocatalytic activity and recycling performance toward selective reduction process under visible light irradiation [29]. In the other case, we recently reported a highly efficient direct Z-scheme Ag 3 PO 4 -ZnO hierarchical photocatalysis by depositing Ag 3 PO4 particles on defect-rich ZnO hierarchical nanosheets used for degeneration of RhB under visible light irradiation [19].…”

Water Splitting By Photocatalytic Reduction

“…So far, many low-dimensional hybrid photocatalysts such as 0D-1D [183][184][185], 0D-2D [186][187][188][189], 1D-1D [190], 1D-2D [191][192][193][194][195][196][197], and 2D-2D [163,164,198,199] have been constructed and applied in environmental and clean energy areas. Here, we focus on the 0D-2D and 2D-2D hybrids and multijunction photocatalysts.…”

Morphology Transition of ZnO Nanorod Arrays Synthesized by a Two-Step Aqueous Solution Method

“…Among them, ZnO, as an important II-VI semiconductor with a direct band gap of 3.37 eV, larger exciton binding energy of 60 mV [9,10] at room temperature, and piezoelectricity [11], has attracted special interest. Especially, vertically aligned ZnO nanorod arrays (ZNAs), due to their non-toxicity, low-cost, large surface to volume ratio, and ease of large scale fabrication, can be employed in many devices, like solar cells, UV lasers, gas sensors, UV detectors, and photocatalysis [12][13][14][15][16][17][18][19][20]. Various methods have been used to synthesize ZNAs, including chemical vapor deposition (CVD) [21,22], pulsed laser deposition (PLD) [23], molecular beam epitaxy (MBE) [10,24], etc.…”