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In this paper, we report the synthesis of ligand-free Au nanoclusters (NCs)/g-C3N4 ultra-thin nanosheets (NSs) composite via a facile wet-impregnation method with post-annealing. On the one hand, post-annealing was used for the exfoliation of multi-layered g-C3N4 to obtain ultra-thin NSs; on the other hand, after Au25(Cys)18 NCs were loaded, post-annealing was further adopted to remove the ligands to obtain clean surface on Au NCs. It is demonstrated that the loaded Au NCs were aggregating resistant by post-annealing. Constructing heterojunctions with appropriate inter-band structures between the ligand-free Au NCs and the ultra-thin g-C3N4 NSs, along with the mono-distribution of the Au NCs and their intimate contact with g-C3N4 NSs ensured the smooth interfacial charge transfer. As a result, the composite photocatalysts exhibited efficient visible-light-induced photocatalytic H2 generation, mainly due to the local electric field enhancement induced by excitation of Au NCs under visible light and the improved charge separation in g-C3N4. This work provides a general strategy for the synthesis of noble metal NCs based composites with clean surface as the efficient photocatalysts for solar energy conversion.
Graphical AbstractA stepwise post-annealing strategy is exploited to prepare g-C3N4 ultra-thin nanosheets modified with highly dispersed ligand-free Au nanoclusters for efficient photocatalytic hydrogen production.
相似文献The development of eco-friendly connection material instead of steel is a challenging problem in timber structures. Following densification, the mechanical properties of low-density species can be significantly improved. Densified wood may be a potential connection material in timber structures. This paper reviewed the different processing for densified wood, and obtained favorable mechanical properties and dimensional stability based on small specimen sizes, which are much less than the applicable sizes in practice. A densification processing with alkali pretreatment was adopted for poplar widely cultivated in the world to produce the densified poplar, which has been rarely reported as connection material. Various specimens of densified poplar were tested to obtain their main mechanical properties such as strength and deformability. The set recovery of densified poplar was also measured to observe their dimensional stability. In addition, the hygroscopic swelling strains for the diameter of densified poplar dowel were measured to present their moisture-dependent behavior. The improved mechanical properties and dimensional stability confirmed the fact that densified poplar with alkali pretreatment can be an optimal connection material.
Graphical abstract 相似文献