The metal/metal oxide semiconductor materials with special photoelectric properties have been widely used for the development of novel photoelectric devices. However, electron transfers at the interfaces of metal and metal oxide are unclear under a photoexcitation process. Herein, the pure WO3 nanorods and Ag nanoparticles (NPs)-loaded WO3 (AWO) nanorods were synthesized by a hydrothermal technique and a two-step method, which includes hydrothermal and magnetron processes. Their corresponding electron excitation and relaxation properties have been revealed by absorption/emission spectra and transmission curves under nonlinear excitation of an ultrafast laser. The dependence relationship for the morphology and structure of one-dimensional (1D) WO3 nanomaterial orientation on the parameters’ adjustment (reaction time and reactant concentration) and formation mechanism was studied. The 1D WO3 nanomaterials show obvious longitudinal growth in the (200) orientation, as well as lateral growth in the (001) and (110) orientations. The size and distribution effects of Ag NPs on the optical properties of WO3 have also been investigated. On the basis of quantum particle coupling between metal (Ag) and metal oxide materials (WO3 nanorods), electron–hole pairs were generated in the semiconductor and strongly enhanced the radiative recombination. The Z-scan results illustrated that the maximum nonlinear absorption coefficient of the AWO (6 W) nanorods was obtained. When charge transfer happens in Ag NPs, the density of the electronic states in the excited/defect states of the WO3 can be regulated. For AWO nanorods, the ground state of Ag undergoes a saturation absorption process and results in reverse saturation absorption of the excited/defect states. Because of their remarkable nonlinear-optical properties, the proposed AWO nanorods will be potential nanocomposite materials for the development of nonlinear absorption modulator devices.
Kanjun Sun,Fengting Hua,Shuzhen Cui,Yanrong Zhu,Hui Peng,Guofu Ma
A novel asymmetric supercapacitor (ASC) is assembled on the basis of an inerratic hexagonal-like WO3 nanorod bundle as a negative electrode and graphene-like alfalfa-derived porous activated carbon (APAC) as the positive electrode in 1 M H2SO4 aqueous electrolyte. The WO3 nanostructures prepared at pH of 1.6, 1.8, 2.0, 2.5 and 3.0 display hexagonal disc-like, nanorod bundle, inerratic hexagonal-like, sphere-like, and needle-shaped nanorod morphology. WO3-2.0, which was prepared at a pH of 2.0, exhibits high specific capacitance (415.3 F g−1 at 0.5 A g−1). APAC-2, which had the mass ratios of dried alfalfa and ZnCl2 as 1 : 2, showed a 3D porous structure, large surface area (1576.3 m2 g−1), high specific capacitance (262.1 F g−1 at 0.5 A g−1), good cycling stability with 96% of initial specific capacitance after 5000 consecutive cycles. The ASC assembled with WO3-2.0 and APAC-2 exhibits high energy density (27.3 W h kg−1 at a power density of 403.1 W kg−1), as well as good electrochemical stability (82.6% capacitance retention after 5000 cycles). Such outstanding electrochemical behavior implies that the electrode materials are promising for practical energy-storage systems.
The appropriate construct of Z-scheme heterostructure composite with high photocatalytic activity has created new opportunities for environmental protection. Herein, graphitic carbon nitride quantum dots/tungsten trioxide (CNQDs/WO 3 ) was firstly fabricated using CNQDs decorated onto the surface of WO 3 nanorod grown along the [110] orientation in hydrothermal environment to construct a Z-scheme heterostructure composite. By various characterization methods, the crystal structure, micro morphology, atomic valence state and surface functional groups of the catalyst were systematically revealed. The results indicated that Z-scheme heterojunctions between CNQDs and WO 3 were successfully constructed. Compared with pure WO 3 , CNQDs/WO 3 exhibited prominent photoreduction performance under visible light irradiation. The optimal 5% CNQDs/WO 3 could reduce almost 100% Cr (VI) under acidic condition with the best photocatalytic activity within 90 min. More than this, 5% CNQDs/WO 3 also displayed excellent stability and recyclability even after five cycles of photoreduction experiments. Based on the free radical quenching experiments, the possible photoreduction reaction mechanism had been proposed in detail. The Z-scheme heterostructure provided the possibility of the generation, rapidly transfer and efficient separation of photogenerated electrons, which were major active species in the Cr (VI) photoreduction process.
危险品化学品经营许可证（带存储）