Xiaohui Ren

2D co-catalytic MoS2 nanosheets embedded with 1D TiO2 nanoparticles for enhancing photocatalytic activity

2D photocatalytic TiO2/MoS2 hybrid nanosheets (HNs) have been prepared via a facile hydrothermal process. X-ray diffraction patterns and Raman spectra are carried out and confirm a well crystalized anatase and 2H-MoS2 hybridization. Additional morphological and microstructural tests verify a distinct MoS2 framework, indicating the relatively stability of the MoS2 nanosheet platform with a high specific surface area. UV–vis spectra and electrochemical impedance spectra exhibit an enhanced light absorption ability and conductivity of TiO2/MoS2 compared to that of just TiO2. Photoelectrochemical (PEC) tests also demonstrate the photocurrent of 20 : 1 TiO2/MoS2 HNs is greatly improved compared to that of as-prepared TiO2. The saturation current density is about 33 µA cm−2 when the applied potential is 0.2 V, which is nearly twice that of pure TiO2 and four times as high as 5 : 1 TiO2/MoS2 HNs and 1 : 1 TiO2/MoS2 HNs. Besides that, the duration test exhibits no detectable distinction after processing 25 cycles. The improved photocatalytic activities are perhaps derived from the high conductivity and the increased active sites for the introduction of co-catalytic MoS2 nanosheets as well as the positive synergetic effect between the TiO2 and MoS2. This work demonstrates that the as-prepared TiO2/MoS2 HNs may have a great potential application in PEC hydrogen production.

A black/red phosphorus hybrid as an electrode material for high-performance Li-ion batteries and supercapacitors

A single elemental hybrid composed of black phosphorus (BP) and red phosphorus (RP) is synthesized via a feasible sonochemical method. BP and RP can construct a new single elemental heterostructure. This kind of structure with an excellent interfacial contact between BP and RP would be beneficial to electron transfer and exhibits a superior electrochemical performance. Compared with the sole RP, the as-prepared BP/RP hybrid exhibits enhanced electrochemical performances as an electrode material for both lithium-ion batteries and supercapacitors. For lithium-ion battery applications, the BP/RP hybrid provides a high cycling performance with an initial discharge capacity of 2449 mA h g−1 and a reversible capacity of 491 mA h g−1 after 100 cycles. For supercapacitor applications, the specific capacitance of the BP/RP hybrid achieves a high value up to about 60.1 F g−1 and a long cycling life with a capacity retention of 83.3% after 2000 cycles. The present study demonstrates that the BP/RP hybrid has potential for application as an electrode with high performances in electrochemical energy-storage devices.

Two-dimensional bismuth nanosheets as prospective photo-detector with tunable optoelectronic performance

Two dimensional Bi nanosheets have been employed to fabricate electrodes for broadband photo-detection. A series of characterization techniques including scanning electron microscopy and high-resolution transmission electron microscopy have verified that Bi nanosheets with intact lamellar structure have been obtained after facile liquid phase exfoliation. In the meanwhile, UV-vis and Raman spectra are also carried out and the inherent optical and physical properties of Bi nanosheets are confirmed. Inherited from the topological characteristics of Bi bulk counterpart, the resultant Bi nanosheet-based photo-detector exhibits preferable photo-response activity as well as environmental robustness. We then evaluate the photo-electrochemical (PEC) performance of the photodetector in 1 M NaOH and 0.5 M Na2SO4 electrolytes, and demonstrated that the as-prepared Bi nanosheets may possess a great potential as PEC-type photo-detector. Additional PEC measurements show that the current density of Bi nanosheets can reach up to 830 nA cm-2, while an enhanced responsivity (1.8 μA W-1) had been achieved. We anticipate that this contribution can provide feasibility towards the construction of high-performance elemental Bi nanosheets-based optoelectronic devices in the future.