Robust and highly active photocatalysts, CdS@MoS, for hydrogen evolution were successfully fabricated by one-step growth of oxygen-incorporated defect-rich MoS ultrathin nanosheets on the surfaces of CdS with irregular fissures. Under optimized experimental conditions, the CdS@MoS displayed a quantum yield of ∼24.2% at 420 nm and the maximum H generation rate of ∼17203.7 umol/g/h using NaS-NaSO as sacrificial agents (λ ≥ 420 nm), which is ∼47.3 and 14.7 times higher than CdS (∼363.8 μmol/g/h) and 3 wt % Pt/CdS (∼1173.2 μmol/g/h), respectively, and far exceeds all previous hydrogen evolution reaction photocatalysts with MoS as co-catalysts using NaS-NaSO as sacrificial agents. Large volumes of hydrogen bubbles were generated within only 2 s as the photocatalysis started, as demonstrated by the photocatalytic video. The high hydrogen evolution activity is attributed to several merits: (1) the intimate heterojunctions formed between the MoS and CdS can effectively enhance the charge transfer ability and retard the recombination of electron-hole pairs; and (2) the defects in the MoS provide additional active S atoms on the exposed edge sites, and the incorporation of O reduces the energy barrier for H evolution and increases the electric conductivity of the MoS. Considering its low cost and high efficiency, this highly efficient hybrid photocatalysts would have great potential in energy-generation and environment-restoration fields.
The development of effective approaches for the preparation of 0D quantum dots (QDs)/2D nanosheets (NSs) heterostructures, which have been proven to be favorable for heterogeneous catalysis, is highly desirable but remains a great challenge. Herein, 0D metal oxide nanocrystals-2D ultrathin g-C N nanosheets (Co O /CNNS) heterostructures are synthesized via a facile chemical reaction, followed by annealing in air. Ultrafine Co O QDs (≈2.2-3.2 nm) are uniformly and tightly attached on the surface of g-C N nanosheets. Detailed characterization reveals that the specially designed unique 0D/2D structure is critical to the high photocatalytic performance for the degradation of tetracycline (TC) via peroxymonosulfate (PMS) activation. The optimal catalyst, namely, Co O /CNNS-1100, exhibits excellent performance and ≈98.7% TC can be degraded under visible light irradiation. Moreover, TC degradation is almost completely insusceptible to several real water samples. Meanwhile, other dye pollutants can also be efficiently degraded by the Co O /CNNS-1100/PMS/vis system. The quenching tests display that that the h , ∙OH, O , and SO are responsible for TC removal. The improved photocatalytic performance can be attributed to the synergistic effect of the photocatalytic- and chemical-processes in the PMS activation. This work gives an insight into the development of multifunctional 0D/2D nanocomposites for further potential applications which are not limited to environmental purification.
Aqueous zinc ion batteries employing metallic zinc anode and aqueous electrolytes are highly attractive electrochemical energy storage technologies owing to their cost effectiveness, intrinsic safety, elemental abundance and competitive gravimetric...
The smaller particle sizes, better dispersion, and more heterojunction interfaces can enhance the photocatalytic performance of photocatalysts. Herein, ultradispersed amorphous silver silicates/ultrathin g-CN nanosheets heterojunction composites (a-AgSiO/CNNS) with intimate interfacial coupling effect were synthesized through the facile in situ precipitation of ultrafine a-AgSiO (∼5.2 nm) uniformly dispersed on the entire surface of hierarchical ultrathin CNNS. In this process, the ultrathin CNNS not only perform as the support to form heterostructures but also are employed as dispersant to confine the aggregation of a-AgSiO nanoparticles. Notably, the optimum photocatalytic activity of a-AgSiO/CNNS-500 composite is ∼36 and 13 times higher than that of CNNS toward the degradation of rhodamine B and tetracycline, respectively. The excellent photocatalytic activity can be attributed to the synergistic interactions of heterojunction with strong interfacial coupling effect, improved visible light absorbance, abundant heterojunction interfaces, and fully exposed reactive sites, which originate from the well-defined nanostructures such as uniform packing of the ultrasmall a-AgSiO, the intimate and maximum coupling interfaces between a-AgSiO and CNNS. We believe that such an easy and scalable synthetic strategy can be further extended to the fabrication of other ultrafine semiconductors coupled with g-CN for increasing its photocatalytic performance.
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