Coupling ZnO with carbon materials using a suitable integration method to form ZnO–carbon composites has been established as a promising strategy to ameliorate the photocatalytic performance of semiconductor ZnO. In this perspective article, we describe the recent advances and current status of enhancing the photocatalytic activity and anti-photocorrosion of semiconductor ZnO by coupling with versatile carbon materials, e.g., C60, carbon nanotube, graphene and other carbon materials. The primary roles of carbon materials in boosting the photoactivity and photostability of ZnO have been outlined and illustrated with some selected typical examples. In particular, the three main kinds of mechanisms with regard to anti-photocorrosion of ZnO by coupling with carbon have been demonstrated. Finally, we give a concise perspective on this important research area and specifically propose further research opportunities in optimizing the photocatalytic performance of ZnO–carbon composites and widening the scope of their potential photocatalytic applications.
Recently, loading ligand-protected gold (Au) clusters as visible light photosensitizers onto various supports for photoredox catalysis has attracted considerable attention. However, the efficient control of long-term photostability of Au clusters on the metal-support interface remains challenging. Herein, we report a simple and efficient method for enhancing the photostability of glutathione-protected Au clusters (Au GSH clusters) loaded on the surface of SiO2 sphere by utilizing multifunctional branched poly-ethylenimine (BPEI) as a surface charge modifying, reducing and stabilizing agent. The sequential coating of thickness controlled TiO2 shells can further significantly improve the photocatalytic efficiency, while such structurally designed core-shell SiO2-Au GSH clusters-BPEI@TiO2 composites maintain high photostability during longtime light illumination conditions. This joint strategy via interfacial modification and composition engineering provides a facile guideline for stabilizing ultrasmall Au clusters and rational design of Au clusters-based composites with improved activity toward targeting applications in photoredox catalysis.
One-dimensional (1D) nanostructures are believed to play a significant role on the horizon of material science, and are a promising class of ideal high performance candidates for energy storage and conversion owing to their unique optical, structural and electronic properties. In particular, 1D nanostructure-based photocatalysts have been attracting ever-growing research attention. In this review article, we mainly focus on systematically summarizing the applications of 1D-based nanocomposites in photocatalysis, including nonselective processes for the degradation of pollutants, direct solar energy conversion to storable fuels and selective transformations for organic synthesis. Particularly, we explore the new directions for boosting the photocatalytic performances of 1D nanostructures, including graphene-1D nanocomposites, surface modification, 1D core–shell nanostructures and different exposed facet effects. It is hoped that this article will promote the efficient harnessing and rational development of the outstanding structural and electronic properties of 1D nanostructures to design more efficient 1D-based photocatalysts towards numerous applications in the field of solar energy conversion.
A series of uniform ZnO nanospheres–reduced graphene oxide nanocomposites (ZnO–RGO NCs) with different weight addition ratios of RGO are successfully synthesized via a facile yet efficient method by intimately coating ZnO nanospheres (NSs) with RGO, which is afforded by electrostatic attraction between positively charged ZnO NSs and negatively charged graphene oxide (GO) in an aqueous medium at room temperature. The photocatalytic test of degradation of Rhodamine B shows that the optimal ZnO–10% RGO NCs exhibit a 5-fold enhancement of photoactivity than bare ZnO NSs, which is ascribed to the integrative synergetic effect of enhanced adsorption capacity, the decreased recombination of the electron–hole pairs and the enhanced ultraviolet light absorption intensity. Significantly, the recycled photoactivity tests show that, for ZnO–RGO NCs, the anti-photocorrosion of ZnO NSs is improved remarkably which is attributed to the effective hybridization of ZnO NSs with the RGO sheet via intimate surface coating. Such a significant photoactivity enhancement and anti-photocorrosion phenomenon can not be obtained by simply integrating RGO with ZnO NSs that are not subject to surface charge modification, which thus indicates the importance of intimate surface coating of ZnO with RGO toward the efficiency of enhancement of photoactivity and particularly the anti-photocorrosion of ZnO.