Preparation of point-line Bi2WO6@TiO2 nanowires composite photocatalysts with enhanced UV/visible-light-driven photocatalytic activity

Bi₂WO₆@TiO₂ nanowires composite photocatalysts (BWO-TNWS) with point-line structures have been successfully fabricated by hydrothermalsynthesis method, and characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectra (UV–vis DRS), photoluminescence (PL) and electrochemical impedance spectroscopy (EIS). The effects of coupling narrow-band-gap semiconductor Bi₂WO₆ (BWO) to photocatalytic activity for degrading Rhodamine B (RhB) and Phenol under UV–vis light irradiation were investigated. The results demonstrate that the photocatalytic activities of the prepared photocatalysts are associated with the content of Bi₂WO₆ (BWO). 20% BWO-TNWS (containing 20 wt% BWO) composite exhibits the highest degradation rate for RhB and Phenol up to 78% and 33%, respectively. It can be concluded that the improved photocatalytic performance of the BWO-TNWS composite is mainly ascribed to its high photoinduced charge separation rate resulting from the effective heterojunction structure of BWO and TNWS, as well as the enlarged optical response range owing to coupling narrow-band-gap semiconductor BWO.     

Regeneration of novel visible-light-driven Ag/Ag3PO4@C3N4 hybrid materials and their high photocatalytic stability

Novel visible-light-driven Ag₃PO₄@C₃N₄PO₄ loaded with metal Ag were synthesised via an anion-exchange precipitation method and regenerated by H₂O₂ and NaNH₃HPO₄. The obtained Ag/Ag₃PO₄@C₃N₄ and regenerated Ag/Ag₃PO₄@C₃N₄ were characterised by XRD, XPS, SEM and UV–vis. The XRD and UV–vis results revealed that the crystal structure and light adsorption property of Ag/Ag₃PO₄@C₃N₄ were similar to that of regenerated Ag/Ag₃PO₄@C₃N₄. The XPS result showed that the metallic Ag⁰ deposited on the surface of Ag/Ag₃PO₄@C₃N₄ and regenerated Ag/Ag₃PO₄@C₃N₄. The Ag/Ag₃PO₄@C₃N₄ hybrids displayed remarkable photocatalytic activity and stability after regeneration. Compared with pure Ag₃PO₄ or C₃N₄, the Ag/Ag₃PO₄@C₃N₄ and regenerated Ag/Ag₃PO₄@C₃N₄ enhancement in the photodegradation rate towards methyl orange is observed over under visible light irradiation. The enhanced photocatalytic performance was attributed to the synergistic effect between Ag₃PO₄ and C₃N₄ and a small amount of Ag⁰ which suppresses the charge recombination during photocatalytic process. This work could provide new insights into the fabrication of high stability visible photocatalysts and facilitate their practical application in environment issues.     

Highly efficient visible-light driven AgBr/Ag3PO4 hybrid photocatalysts with enhanced photocatalytic activity

Highly efficient visible-light-driven AgBr/Ag₃PO₄ hybrid photocatalysts with different mole ratios of AgBr were prepared via an in-situ anion-exchange method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) technique. Under visible light irradiation (>420 nm), the AgBr/Ag₃PO₄ photocatalysts displayed the higher photocatalytic activity than pure Ag₃PO₄ and AgBr for the decolorization of acid orange 7 (AO 7). Among the hybrid photocatalysts, AgBr/Ag₃PO₄ with 60% of AgBr exhibited the highest photocatalytic activity for the decolorization of AO 7. X-ray photoelectron spectroscopy (XPS) results revealed that AgBr/Ag₃PO₄ readily transformed to be Ag@AgBr/Ag₃PO₄ system while the photocatalytic activity of AgBr/Ag₃PO₄ remained after 5 recycling runs. In addition, the quenching effects of different scavengers displayed that the reactive h⁺ and O₂^∙− play the major role in the AO 7 decolorization. The photocatalytic activity enhancement of AgBr/Ag₃PO₄ hybrids can be ascribed to the efficient separation of electron–hole pairs through a Z-scheme system composed of Ag₃PO₄, Ag and AgBr, in which Ag nanoparticles act as the charge separation center.     

Synthesis and characterization of g-C3N4/BiFeO3 composites with an enhanced visible light photocatalytic activity

The novel visible light-induced g-C₃N₄/BiFeO₃ composites were successfully synthesized by introducing BiFeO₃ into polymeric g-C₃N₄. The structures and optical properties of composites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), field-emission transmission electron microscope (TEM), UV–vis diffuse reflection spectroscopy (DRS), respectively. For the degradation of Rhodamine B (RhB), the g-C₃N₄/BiFeO₃ composites exhibited significantly higher visible light photocatalytic activity than that of a single semiconductor. The optimal percentage of doped g-C₃N₄ was 50%. Both photooxidation and photoreduction processes follow first order kinetics. In addition, the stability of the prepared photocatalyst in the photocatalytic process was also investigated. The enhanced photocatalytic performance could be due to the high separation efficiency of the photogenerated electron–holes pairs. The possible photocatalytic mechanism of g-C₃N₄/BiFeO₃ was proposed to guide the further improvement of their photocatalytic activity.     

Synthesis of micro-nano Ag3PO4/ZnFe2O4 with different organic additives and its enhanced photocatalytic activity under visible light irradiation

Several novel micro-nano Ag₃PO₄/ZnFe₂O₄ with excellent magnetic separation property and photocatalytic performance were successfully synthesized using different organic additives for the first time. In the composite, Ag₃PO₄ with flower-like, quadrangular prism and flake structures were obtained when the organic additive is hexadecyl trimethyl ammonium bromide (CTAB), sodium diethyldithiocarbamate (DDTC), or DL-malic acid (DLMA), respectively, while the ZnFe₂O₄ showed uniform spherical structure. From the results of the photocatalytic activity analysis, the Ag₃PO₄/ZnFe₂O₄ gained with the organic additive of DDTC showed the highest photocatalytic capability for 2, 4-dichlorophenol (2, 4-DCP) degradation under visible light irradiation compared with those of CTAB and DLMA as the additives. Moreover, the composition of the composite seriously influences the photocatalytic activity, and when the mass ratio of Ag₃PO₄ and ZnFe₂O₄ in the Ag₃PO₄/ZnFe₂O₄ (DITCH) is 9:1, the apparent photo degradation rate constant of 2, 4-DC is 0.0155 min⁻¹, which is 5.74 times of ZnFe₂O₄ (0.0027 min⁻¹) and 1.89 times of Ag₃PO₄ (0.0082 min⁻¹). Finally, the photocatalytic mechanism of Ag₃PO₄/ZnFe₂O₄ was discussed based on the heterojunction energy-band theory and Z-Scheme theory in detail.     

Fabrication of Bi2MoO6 nanoplates hybridized with g-C3N4 nanosheets as highly efficient visible light responsive heterojunction photocatalysts for Rhodamine B degradation

The Bi₂MoO₆/g-C₃N₄ heterojunction photocatalysts have been successfully fabricated using a simple liquid chemisorptions and thermal post-treatment. These nanostructured Bi₂MoO₆/g-C₃N₄ composites were extensively characterized by X-ray diffraction(XRD), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR),UV–vis diffuse reflectance spectra (UV–vis DRS) and Photoluminescence (PL). The photocatalytic results show that 20 wt% Bi₂MoO₆/g-C₃N₄ sample exhibits efficient visible light activity and excellent photo-stability. The kinetic constant of RhB degradation over 20 wt% Bi₂MoO₆/g-C₃N₄ is about 5 and 2.5 times higher than that over pure Bi₂MoO₆ and g-C₃N₄ nanosheets, respectively. The enhanced photocatalytic performance is attributed to the construction of heterogeneous interface to promote photo-induced charge carrier pairs separation.     

Comparison of interfacial and electrical properties between Al2O3 and ZnO as interface passivation layer of GaAs MOS device with HfTiO gate dielectric

GaAs metal–oxide–semiconductor(MOS) capacitors with HfTiO as the gate dielectric and Al2O3 or ZnO as the interface passivation layer(IPL) are fabricated. X-ray photoelectron spectroscopy reveals that the Al2O3 IPL is more effective in suppressing the formation of native oxides and As diffusion than the ZnO IPL. Consequently, experimental results show that the device with Al2O3 IPL exhibits better interfacial and electrical properties than the device with ZnO IPL: lower interface-state density(7.21012 eV1cm2/, lower leakage current density(3.60107A/cm2 at Vg D1 V) and good C–V behavior.     

Self‐Sacrifice Template Fabrication of Hierarchical Mesoporous Bi‐Component‐Active ZnO/ZnFe2O4 Sub‐Microcubes as Superior Anode Towards High‐Performance Lithium‐Ion Battery

In the work, a facile yet efficient self‐sacrifice strategy is smartly developed to scalably fabricate hierarchical mesoporous bi‐component‐active ZnO/ZnFe₂O₄ (ZZFO) sub‐microcubes (SMCs) by calcination of single‐resource Prussian blue analogue of Zn₃[Fe(CN)₆]₂ cubes. The hybrid ZZFO SCMs are homogeneously constructed from well‐dispersed nanocrstalline ZnO and ZnFe₂O₄ (ZFO) subunites at the nanoscale. After selectively etching of ZnO nanodomains from the hybrid, porously assembled ZFO SMCs with integrate architecture are obtained accordingly. When evaluated as anodes for LIBs, both hybrid ZZFO and ZFO samples exhibit appealing electrochemical performance. However, the as‐synthesized ZZFO SMCs demonstrate even better electrochemical Li‐storage performance, including even larger initial discharge capacity and reversible capacity, higher rate behavior and better cycling performance, particularly at high rates, compared with the single ZFO, which should be attributed to its unique microstructure characteristics and striking synergistic effect between the bi‐component‐active, well‐dispersed ZnO and ZFO nanophases. Of great significance, light is shed upon the insights into the correlation between the electrochemical Li‐storage property and the structure/component of the hybrid ZZFO SMCs, thus, it is strongly envisioned that the elegant design concept of the hybrid holds great promise for the efficient synthesis of advanced yet low‐cost anodes for next‐generation rechargeable Li‐ion batteries.