Search

Exploring advanced electrocatalysts for the hydrazine oxidation reaction (HzOR) could expedite the applications of direct hydrazine fuel cells (DHzFCs) for zero-carbon economics.

Developing advanced electrocatalysts to convert CO2 into liquid fuels such as ethanol is critical for utilizing intermittent renewable energy. The formation of ethanol, however, is generally less f...

Copper doped ZnO hierarchical nanostructures have been synthesized with a facile solution route at room temperature. Structural properties of the as-synthesized nanostructures have been studied X-ray diffraction, field emission scanning electron microscopy with energy dispersive. Meanwhile, light-absorption properties were studied with UV–Vis absorption spectroscopy. Photocatalytic performance of Cu-doped ZnO hierarchical nanostructures were evaluated by the light-driven degradation of methylene blue. The results indicated that Cu doping lead to the augment of average crystallite size of ZnO crystals. Moreover, morphological evolution of ZnO nanostructures was found with the addition of Cu ions. The photocatalytic test showed that there is an optimum Cu doping concentration which results in the enhancement of photocatalytic performance of Cu doped ZnO hierarchical nanostructures, compared with pristine ZnO. A novel and reasonable mechanism was proposed. It is believed that the enhanced photocatalytic performance of Cu doped ZnO hierarchical nanostructures can be attributed to the formation of acceptor level (Cu2+–Cu+) in the midgap of ZnO, which improved the utilization of light and separation efficiency of photogenerated electron hole pairs.

Electrochemical reduction of carbon dioxide to value-added fuels offers a promising method to solve increasingly serious environmental problems and alleviate energy crisis. Herein, we report a facile method by coating Cu electrode with CeO2 nanoparticles to largely enhance the C2+ products selectivity during CO2 electroreduction. The Faradaic efficiency of C2+ products for optimal CeO2-coated Cu electrode reached a high value of 61 % at -1.05 V vs RHE, and exhibited good stability for over 9 h of CO2 electrolysis. The CeO2 nanoparticles were found to induce oxidative corrosion of the Cu foil, leading to a CuOx layer in contact with the CeO2 nanoparticles. The interface between CeO2 nanoparticles and oxide-derived Cu might be attributed to the enhanced catalytic activity for C2+ products by promoting the C C coupling process.

Nanoparticles possess improved properties which are supported by the specific characteristics such as size, distribution and morphology. The synthesis of zinc oxide nanoparticles (ZnO-NPs) has attracted a great deal of attention for their wide and advanced applications. Confined growth of ZnO-NPs in the channels has been more superior for it offers finer tailoring of size and shape based on the pore size of anodic aluminum oxide (AAO) membrane. In our research, we have conducted a comparative study of the synthesis of ZnO-NPs through three different methods with the template synthesis of AAO membrane. The results indicate that the electrochemical deposition is preferable to the other two for it gives a narrow and dense distribution of ZnO-NPs. The growth processes and mechanisms of these various methods have also been summarized thoroughly. This work may provide us with some new thoughts into the fabrication of NPs and give us a blueprint to “design” materials.

The integration of low dimensions nanoscale building blocks into 3D architectures has attracted great scientific attention. We have obtained the novel hierarchical flower-like ZnO nanostructures self-assembled by nanorods via a facile hydrothermal method. The as-synthesized samples were characterized with various technologies. The field emission scanning electron microscope (FESEM) images indicated that hydroxide ions play a significant role on the formation of hierarchical flower-like ZnO nanostructures. The X-ray diffraction (XRD) result proved that the nanocrystals were well crystallized hexagonal wurtzite structure. A possible growth mechanism of the nanostructures was proposed based on the effects of hydroxide ions. And the TEM imagines provided some important evidence for the proposed growth mechanism. UV–vis adsorption and photoluminescence (PL) spectra results indicated that the obtained ZnO nanostructurs have a good optical-absorption and photoluminescence property. The as-synthesized ZnO nanostructures exhibited superior photocatalytic performance, which was higher than that of commercially available ZnO.

In this work, a series of Zn-doped dendritic-like CdS structures have been synthesized by a simple hydrothermal method. The as-prepared samples have been characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive spectrometer (EDS), ultraviolet-visible (UV–vis) and room temperature photoluminescence (PL). Their photocatalytic activities have been evaluated by the photocatalytic degradation of methylene blue (MB) under simulated visible-light irradiation. XRD results indicate that the phase of Zn:CdS was hexagonal phase. XRD and EDS results indicate that Zn 2+ was successfully introduced into CdS. FESEM results indicate that low Zn 2+ doping concentration can keep the dendritic-like CdS structures, but the morphologies of Zn:CdS are flower-like structures at high Zn 2+ doping concentration. UV–vis results indicate that doping Zn 2+ can be used to improve the absorbing capability of dendritic-like CdS for visible light, and the content of Zn 2+ affects the band gap. PL results indicate that doping Zn 2+ can be used to improve the luminescence property of dendritic-like CdS. Photocatalytic results indicate that doping Zn 2+ is conducive to improve the photocatalytic efficiency of dendritic-like CdS to MB, and the highest degradation rate is 92.8%. And the photocatalytic mechanism of Zn-doped dendritic-like CdS to MB is also described.

A novel Mn doped flower-like ZnO hierarchical structures were successfully synthesized with a facile ion-exchange method. Structural properties of the synthesized photocatalysis have been investigated with XRD, FESEM equipped with energy dispersive spectroscopy, while UV–vis and PL spectroscopy were employed to study their optical properties. The inner structure of doped ZnO hierarchical structure can be finely transformed from nanosheets to nanorods and to nanoparticles with the increasing of doping contents. All the synthesized Mn/ZnO samples exhibit strong blue-violet emission. Furthermore, the optical absorption towards visible light of ZnO was significantly enhanced due to the incorporation of Mn ions. The photocatalytic results indicate that photocatalytic activity of ZnO was enhanced with the doping of Mn and there is an optimum Mn doping level, leading to the highest photocatalytic performance.

Novel urchin-like ZnO nanostructures were successfully synthesized via an electrodeposition-hydrothermal method and characterized using various analytical instruments. The as prepared samples were characterized by FESEM, XRD, UV–Vis, PL and photocatalytic test. And the effects of the electrodeposition time on the morphology, structure and optical properties have been investigated. In the FESEM, well defined shape of urchin-like ZnO nanostructures was generated. The band gaps of urchin-like ZnO nanostructures, determined from UV–Vis absorption spectra, are 3.13 eV. Photocatalytic investigation of ZnO nanostructures was carried out using methylene blue aqueous solution under UV–visible illumination. Urchin-like ZnO nanostructures prepared under 10 min showed enhanced photocatalytic performance in comparison with the others. The enhanced photocatalytic activity for urchin-like ZnO nanostructures might be resulting from the higher concentration of surface oxygen vacancies.

TiO2 nanotube arrays co-sensitized with SnS2 and CdS nanoparticles (SnS2/CdS/TiO2 NTs) were successfully fabricated by SILAR method. The as-synthesized SnS2/CdS/TiO2 NTs were characterized with X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS) and ultraviolet-visible (UV–vis). Their photocatalytic activities have been investigated on the degradation of methylene blue under simulated solar light irradiation. XRD results indicate that TiO2 NTs were mainly anatase phase, SnS2 and CdS were highly crystallized. FESEM results indicate that TiO2 NTs can keep the nanotubular structures at low deposition concentration. UV–vis results indicate that SnS2 and CdS can be used to improve the absorbing capability of TiO2 NTs for the visible light. And the band gap of SnS2/CdS/TiO2 NTs is 1.95 eV. Photocatalytic results indicate that SnS2 nanoparticles are conducive to improve the photocatalytic efficiency. And the highest degradation rate to methylene blue of SnS2/CdS/TiO2 NTs is 94.5%. At last, the photocatalytic mechanism of SnS2/CdS/TiO2 NTs to methylene blue is also described.

In this paper, a series of CdS/TiO 2 NTs have been synthesized by SILAR method. The as-prepared CdS/TiO 2 NTs have been analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), and ultraviolet–visible (UV–vis). And their photocatalytic activities have been investigated on the degradation of methylene blue under simulated solar light irradiation. XRD results indicate that TiO 2 NTs were anatase phase, CdS nanoparticles were hexagonal phase. FESEM results indicate that low deposition concentration can keep the nanotubular structures. UV–vis results indicate that CdS can be used to improve the absorbing capability of TiO 2 NTs for visible light, and the content of CdS affects the band gap. Photocatalytic results indicate that CdS nanoparticles are conducive to improve the photocatalytic efficiency of TiO 2 NTs, and the highest degradation rate can reach 93.8%. And the photocatalytic mechanism of CdS/TiO 2 NTs to methylene blue is also described.

Dendritic-like CdS and flower-like CdS structures have been prepared by hydrothermal method. The as-prepared CdS have been analyzed by X-ray diffraction, field emission scanning electron microscopy (FESEM), ultraviolet–visible and room temperature photoluminescence (PL). And the photocatalytic activities also have been investigated. FESEM results indicate the role of SDBS is to make the CdS crystals assemble together. The optical energy band gap of dendritic-like CdS is 2.46 eV, and flower-like CdS is 2.48 eV. PL results show that dendritic-like CdS and flower-like CdS emit both blue and green fluorescence. Photocatalysis results show that the catalytic efficiency of dendritic-like CdS is better than flower-like CdS.

This paper derives the relationship between drag coefficient and electrical power of generator by deducing the connection between drag coefficient and rotor power coefficient. The efficiency losing state of running is introduced to the simulation of aging of blade and control strategy and using variable-pitch control is utilized under the efficiency losing state of running. The simulation result of software Matlab display that wind turbine operates safely by using the strategy under efficiency losing state of running.

This paper derives the relationship between the drag coefficient and the electrical power of the generator by deducing the connection between the drag coefficient and the rotor power coefficient. The efficiency losing state of running is introduced to the simulation of the aging of the blade and the control strategy that combining the pitch control and generator torque-speed control is utilized under the efficiency losing state of running. The simulation results of the software Bladed display that the wind turbine operates safely by using the strategy under the failure operation.