| Semiconductor-mediated photocatalysis has received enormous attention as it holds great promise to address the worldwide energy and environmental issues, such as photocatalytic hydrogen generation and degradation of pollutants. To overcome the serious drawbacks of fast photogenerated carriers recombination, poor photostability and limited light absorption range of single semiconductor photocatalysts, many strategies have been developed in the past few decades and the most widely used one is to develop photocatalytic heterojunctions. The achieved progress in this field indicates that forming heterojunctions affords a promising route to enhance the photocatalytic efficiencies of photocatalytic semiconductors. However, the studies in this area are currently unsystematic, and the heterojunction systems with high efficiency, low cost and stability are needed to be further developed. Based on above background and our conditions, we designed serval semiconductor heterojunction photocatalysts for the application in solar water splitting and environmental remediation. Details are as follows:1. Vertically aligned nanosheet heterostructures with partly reduced MoO3 cores and adjustable MoS2 shells were fabricated via two-step chemical vapor deposition (CVD). The as-synthesized MoS2/MoOx heterostructures exhibit enhanced visible-light photocatalytic activity and good compatibility in a wide range of PH values for the degradation of organic dyes, both of which are of significance for practical applications. The vertically grown nanosheets form a three-dimensional mesh structure, creating a large specific surface area for the optical absorption and the catalytic redox reaction. In particular, the sulfidation-produced MoS2 coating layer provides an effective protective against photocorrosion in a wide PH window, and meanwhile modulates the energy band structure to promote the absorption of visible-light photons and the separation of photo-generated electron-hole pairs.2. We report the ZnO quantum dots (QDs) dispersed in hole scavenger (HS) matrix containing S2" and SO32- groups as a high-performance photocatalyst for H2 generation. The as-synthesized ZnO QDs were hybridized orderly with HS groups via water dissolving ethanol dynamic process, forming a stable ZnO QDs/HS hybrid hydrosol. Such a composite performs a recyclable H2 production with the high rate of 260 μmol h-1 g-1, which is around 50 times that of pure ZnO QDs. The improved photocatalytic activity and durability were attributed to the synergistic actions between ZnO QDs and HS groups in this hybrid catalyst for increasing surface area, capturing more photons, scavenging defects and holes, as well as collecting photogenerated electrons.3. Multi-component heteronanostructures are considered as attractive materials for energy conversion applications. There is a long-standing demand to construct more sophisticated heterostructures for steering charge-carrier flow in semiconductor systems. Herein we fabricate a large-scale of three-dimensional branched CuxO/ZnO@Au heterostructure consisting of CuO nanowires and grafted ZnO nanodisks decorated with Au nanoparticles via sequential hierarchical assemblies. This tree-like hetero-nanostructure ensures well-steered transfer of photo-generated electrons to the exposed ZnO while holes to the CuO backbone with concerted efforts from p-n junctions, polar ZnO facets and Au plasmon, resulting in the significantly enhanced photocatalytic hydrogen evolution performance.
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