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Bismuth vanadate (BiVO4) is a promising photocatalytic material for use in environmental protection and water splitting. However, its short photogenerated carrier lifetime and narrow visible-light response restrict its extensive application. Herein, a novel electrospinning method was developed to prepare bismuth (Bi)-modified BiVO4 (Bi/BiVO4) porous nanofibers. The morphologies, structures, and chemical states of the obtained samples were characterized using a series of analytical techniques. The photocatalytic performance of the Bi/BiVO4 porous nanofibers was evaluated via the photocatalytic degradation of methylene blue (MB) under visible-light irradiation. The enhanced visible-light photocatalytic activity of Bi/BiVO4 can be attributed to the Bi nanoparticles, which exhibit a surface plasmon resonance (SPR) effect and have semiconductor character, extending the optical absorption of BiVO4 and restraining the recombination of electron–hole pairs during the photocatalytic degradation process, respectively. In this work, new insight is provided into the fabrication of a Bi/BiVO4 composite, which can act as an outstanding visible-light responsive photocatalyst, facilitating its application in the field of environmental protection. [ABSTRACT FROM AUTHOR]

Ceramic matrix nanocomposites containing graphene possess superior mechanical properties. However, these nanocomposites are very difficult to be prepared using the conventional methods due to severe grain growth and simultaneous degradation of the graphene at high sintering temperatures and long dwell time. Herein, the dense ZrO2/rGO (reduced graphene oxide) nanocomposites are successfully fabricated by flash sintering of the green compacts consisting of ZrO2 nanoparticles and graphene oxide (GO) at 893–951℃ in merely 5 seconds under the alternating current (AC) electric fields of 130–150 V cm−1. The GO can be in situ thermal reduced during the flash sintering. The as‐prepared ZrO2/rGO nanocomposites exhibit excellent mechanical properties. This study presents a green and simple approach to fabricate the dense ceramic matrix nanocomposites reinforced with graphene at low temperatures in a short time. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) nanosheets are promising candidates as earth-abundant and low-cost catalyst for hydrogen evolution reaction (HER). Nevertheless, compared with the benchmark Pt/C catalyst, the application of MoS2 nanosheets is limited to its relatively low catalytic activity, especially in alkaline environments. Here, we developed a dual-cation doping strategy to improve the alkaline HER performance of MoS2 nanosheets. The designed Ni, Co co-doped MoS2 nanosheets can promote the tandem HER steps simultaneously, thus leading to a much enhanced catalytic activity in alkaline solution. Density functional theory calculations revealed the individual roles of Ni and Co dopants in the catalytic process. The doped Ni is uncovered to be the active site for the initial water-cleaving step, while the Co dopant is conducive to the H desorbing by regulating the electronic structure of neighboring edge-S in MoS2. The synergistic effect resulted by the dual-cation doping thus facilitates the tandem HER steps, providing an effective route to raise the catalytic performance of MoS2 materials in alkaline solution. [ABSTRACT FROM AUTHOR]

Ni-based heterostructures have been regarded as promising catalysts for the hydrogen evolution reaction (HER) in alkaline solutions due to its high efficiency in catalyzing the water dissociation process. Therefore, an in-depth understanding of the water-dissociation-related activity of Ni species within varied structures and coordination environments is significant for the design of novel catalysts. Herein, we synthesized three types of Ni-based heterostructures, namely NiS/MoS2, NiSe/MoS2 and NiSe2/MoS2 by a controllable route to investigate their catalytic trends and origins of the HER under alkaline conditions. Combined with experimental data and theoretical calculation results, we revealed that the alkaline HER activity of the heterostructures relies on the catalyzing ability of Ni species in the Volmer step, which is associated with the d-band center, and is further related to the coordination condition of the Ni atoms in the chalcogenides. With the highest valence state and d-band center among the samples, Ni atoms in NiS exhibit the fastest reaction rate in the Volmer step, thus providing the best catalytic activity for the NiS/MoS2 heterostructure in the alkaline HER. Furthermore, an activity trend for the Ni chalcogenides in the Volmer step, in the order of NiS > NiSe2 > NiSe, has been proposed, which is expected to contribute insights into the design of novel heterostructured catalysts. [ABSTRACT FROM AUTHOR]

To develop new phosphor materials for optical temperature sensing application, a series of Yb3+-Tb3+ and Eu3+ doped Ca2Gd8(SiO4)6O2 (CGS) phosphors were designed by solid-state reaction method. Upon 980 nm excitation, the green emission of Tb3+ was observed in the CGS:0.8Yb3+, xTb3+ (0.08 ≤ x ≤ 1.2) phosphors, which could be mainly owing to the cooperative energy transfer from Yb3+ to Tb3+. The corresponding upconversion (UC) luminescence mechanism was studied by using the dependence of UC emission intensity on excitation powder. The temperature-dependence indicates that the ratio of the Tb3+ emission intensities of I5D4 and I5D3 changes with temperature, which shows a linear relationship. The high absolute sensitivity was achieved to be about 0.431 K−1. Upon 463 nm excitation, the Eu3+ 5D0,1-7FJ transitions were found in the Eu3+-activated CGS. The investigation on temperature-dependence reveals that with increasing temperature the intensities of 5D0-7FJ transitions decrease but those of 5D1-7FJ transitions increase gradually, owing to the thermally coupled 5D0 and 5D1 levels. The fluorescence lifetime based temperature sensing properties was studied in this sample. [ABSTRACT FROM AUTHOR]

Carbon quantum dots/TiO2 nanotubes composites were prepared by a simple technical route through which TiO2 nanotubes prepared by electrospinning were dispersed in carbon quantum dots solution, and dried at 80 °C. The results indicated that the TiO2 nanotubes composites were combined with the carbon quantum dots. The photocatalytic activity of the carbon quantum dots/TiO2 nanotubes composites was investigated by the degradation of rhodamine B under visible light irradiation, and it was demonstrated to be significantly enhanced compared with that of pure TiO2 nanotubes. Through analysis, this enhancement of visible light photocatalytic activity was attributed to the carbon quantum dots with the unique up-converted photoluminescence behavior. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc ion batteries (AZIBs) have gained considerable attention owing to their low cost and high safety, but dendrite growth, low plating/stripping efficiency, surface passivation, and self-erosion of the Zn metal anode are hindering their application. Herein, a one-step in situ molecular engineering strategy for the simultaneous construction of hierarchical MoS 2 double-layer nanotubes (MoS 2 -DLTs) with expanded layer-spacing, oxygen doping, structural defects, and an abundant 1T-phase is proposed, which are designed as an intercalation-type anode for "rocking-chair" AZIBs, avoiding the Zn anode issues and therefore displaying a long cycling life. Benefiting from the structural optimization and molecular engineering, the Zn 2+ diffusion efficiency and interface reaction kinetics of MoS 2 -DLTs are enhanced. When coupled with a homemade ZnMn 2 O 4 cathode, the assembled MoS 2 -DLTs//ZnMn 2 O 4 full battery exhibited impressive cycling stability with a capacity retention of 86.6% over 10 000 cycles under 1 A g -1 anode , outperforming most of the reported "rocking-chair" AZIBs. The Zn 2+ /H + cointercalation mechanism of MoS 2 -DLTs is investigated by synchrotron in situ powder X-ray diffraction and multiple ex situ characterizations. This research demonstrates the feasibility of MoS 2 for Zn-storage anodes that can be used to construct reliable aqueous full batteries.

Molybdenum disulfide (MoS 2 ) nanosheets are promising candidates as earth-abundant and low-cost catalyst for hydrogen evolution reaction (HER). Nevertheless, compared with the benchmark Pt/C catalyst, the application of MoS 2 nanosheets is limited to its relatively low catalytic activity, especially in alkaline environments. Here, we developed a dual-cation doping strategy to improve the alkaline HER performance of MoS 2 nanosheets. The designed Ni, Co co-doped MoS 2 nanosheets can promote the tandem HER steps simultaneously, thus leading to a much enhanced catalytic activity in alkaline solution. Density functional theory calculations revealed the individual roles of Ni and Co dopants in the catalytic process. The doped Ni is uncovered to be the active site for the initial water-cleaving step, while the Co dopant is conducive to the H desorbing by regulating the electronic structure of neighboring edge-S in MoS 2 . The synergistic effect resulted by the dual-cation doping thus facilitates the tandem HER steps, providing an effective route to raise the catalytic performance of MoS 2 materials in alkaline solution., (© 2021 IOP Publishing Ltd.)