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The graphitic carbon nitride (g‐C3N4) materials with many intriguing properties have attracted much attention in photocatalysis. The photocatalytic activity of g‐C3N4 is hindered by serious aggregation and limited exposed active sites. Herein is shown that nanosized g‐C3N4 can be simply obtained by a superfast high‐pressure homogenization approach. The high‐pressure homogenization treatment can provide strong force to cut and/or to exfoliate the bulk g‐C3N4 into nanosized g‐C3N4 with good dispersion. Moreover, choosing different solvents during treatment can cause a different surface structure of as‐prepared nanosized g‐C3N4. In addition, the narrow bandgap properties, the high photogenerated charge carrier separation, and the transport abilities are achieved in as‐prepared nanosized g‐C3N4 because of the retaining conjugated C3N4 system. Specifically, the photocatalytic activities of as‐prepared nanosized g‐C3N4 have been significantly enhanced in terms of degradation of organic dye Rhodamine B (RhB) under visible light irradiation (10 times higher than that of bulk g‐C3N4). These findings can provide a promising and simple approach to the exfoliation, nanonization, and surface functionalization of 2D layered materials. [ABSTRACT FROM AUTHOR]

Anatase/brookite TiO2-Bi2WO6 multiheterojunction photocatalyst (TabB) has been synthesized via solvothermal method and its physiochemical properties compared with anatase TiO2-Bi2WO6 (TaB) and brookite TiO2-Bi2WO6 (TbB) with single-heterojunction structure. Based on X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) analyses, a heterojunction was formed between TiO2 and Bi2WO6 crystals. All of the TaB, TbB, and TabB samples consisted of free plate-like Bi2WO6 particles covered by many TiO2 nanoparticles. Compared with pure TiO2 (anatase and brookite), the absorption band edge of TabB was red-shifted and the bandgap decreased. The photocatalytic activity of the as-prepared samples under visible-light irradiation was investigated using rhodamine B (RhB), revealing photocatalytic activity in the order TabB > TaB > TbB. The heterojunction structure played a vital role in enhancing charge carrier separation and thus enhancing the photocatalytic activity. The related mechanism of the heterojunction photocatalyst is systematically discussed. [ABSTRACT FROM AUTHOR]

Mesoporous composite films of titania (TiO) and antimony-doped tin oxide (ATO) were prepared on titanium plate substrates from pastes by the doctor-blade method. The photoelectrochemical properties of the samples with different ATO contents were investigated by the degradation of methylene blue under UV light irradiation. It was found that the photocatalytic activity of TiO was significantly improved with the help of the introduction of ATO nanocrystals and a forward bias. The synergetic effect of ATO and bias was analyzed by electrochemical impedance spectra (EIS). The EIS analysis results demonstrated that the separation of photogenerated electron-hole pairs can be efficiently enhanced by introducing ATO nanoparticles and applying an external bias. [ABSTRACT FROM AUTHOR]

Abstract: Cu2+-doped TiO2 film on stainless steel substrates was prepared using sol–gel method. Based on XRD and SEM analysis results, the as-prepared film was mainly in anatase phase. The film was smooth and the thickness of the film was about 2μm. The UV–vis absorption of Cu2+-doped TiO2 was extended to visible range, which is favorable for the utilization of solar light. The photoelectrochemical properties of the samples were investigated via electrochemical impedance spectrum (EIS). The EIS plots demonstrated that the Cu2+-doped TiO2 can be excited under visible light irradiation and the photo-generated electron–hole pairs can be separated efficiently by applying an external bias. The degradation experiments for methylene blue and methyl orange in different processes showed that the photo-response range of TiO2 could be extended by doping Cu2+ ion and the photocatalytic activity of TiO2 could be enhanced with the help of a forward bias. [Copyright &y& Elsevier]

Anatase TiO nanocrystal colloids with high dispersion and photocatalytic activity were rapidly synthesized from peroxo-titanium-acid precursor by microwave-assisted hydrothermal method within 30 min at low temperature (120-180 °C). The transmission electron microscopy results indicate that the as-prepared TiO have a narrow particle size distribution (25-29 nm) and high dispersion. The crystal structure of all these products are pure anatase phase (XRD, Raman), and they show good crystallinity and large surface area (N adsorption-desorption measurements BET). The results of the UV-Visible absorbance and Fourier transform infrared spectra indicate that the surface peroxo group Ti(O) still remains in TiO nanoparticles prepared by microwave-assisted hydrothermal method at 120 °C, and this surface peroxo group can be decomposed effectively by drying at 140 °C. The photocatalytic activity of the as-prepared TiO were evaluated by the degradation of reactive brilliant red X-3B, it is found that the as-prepared TiO exhibited good photocatalytic performance. Moreover, the existence of surface peroxo group greatly suppressed the photocatalytic activity of the TiO nanoparticles. [ABSTRACT FROM AUTHOR]

Abstract: Stable, neutral TiO2 hydrosols were prepared using TiCl4 as titanium source, HNO3 as peptizing agent, and SiO2 as stabilizer. Based on XRD, TEM, and FTIR measurements, the TiO2 was rodlike anatase crystallite with a major axis of 15–25 nm and a minor axis of 5 nm. Tih name="sbnd" />Si bonds were formed, which suppressed the TiO2 grain growth and stabilized the TiO2 hydrosols. The isoelectric points (IEP) of the series hydrosols were 3.1–4.7 pH values and the absolute zeta potentials of the SiO2-modified TiO2 hydrosols were much higher than 50.0 mV under neutral conditions. Methylene blue and reactive brilliant red X-3B were taken as the simulated pollutants to study the adsorption and photocatalytic properties of the obtained hydrosols. The results suggested that the prepared hydrosols had strong adsorption capacity for cationic pollutants rather than anionic ones, and high photodegradation rate of both cationic and anionic pollutants. [Copyright &y& Elsevier]

Abstract: The Sn4+ doped anatase TiO2 nanocrystals with various amounts of dopant Sn4+ ions were prepared from peroxo-metal-complex precursor by solvothermal method and characterized by XRD, TEM, HRTEM, XPS, ICP-AES and UV–vis spectrophotometer. The experimental results indicated that the dopant Sn4+ substituted Ti4+ in the lattice of TiO2, which reflected in the lattice expansion in both a- and c-direction and change of the binding energy. All the Sn4+ doped TiO2 nanocrystal samples appeared to be anatase evenly with dopant level up to 10mol%. The effect of dopant Sn4+ ions and reaction solvents on physicochemical properties of the obtained Sn4+ doped anatase TiO2 nanocrystals had been discussed. In addition, the growth mechanism and microstructure evolution of Sn4+ doped anatase TiO2 nanocrystals had been suggested. The photocatalytic activity of the Sn4+ doped anatase TiO2 nanocrystals was tested by the degradation of phenol. Compared with the undoped TiO2 sample, the enhanced photocatalytic activity of the Sn4+ doped anatase TiO2 nanocrystals could be attributed to modification of the optical properties and surface state by doping the optimum concentration of Sn4+ ions. [Copyright &y& Elsevier]

Abstract: The preparation of Ti1−x Sn x O2 nanocrystal colloids from peroxo-metal precursor by hydrothermal method was reported in this work. The obtained materials were investigated by means of XRD, Raman, TEM, XPS, ICP-AES, N2 adsorption–desorption measurements (BET), PL and UV–vis spectroscopies technology. Photocatalytic degradation of phenol was studied under UV illumination. The results indicated that Ti1−x Sn x O2 nanocrystal colloids were obtained in the nanometer scale (less than 10nm) and the crystallite size was smaller than pure TiO2. Anatase phase, mixture phase (anatase and rutile) and rutile phase of Sn-doped TiO2 samples were formed, when x <0.04, 0.04< x <0.06 and x ≥0.06, respectively. The Sn4+ dopants presented substitution Ti4+ into the lattice of TiO2 alongside increasing the surface oxygen vacancies and the surface hydroxyl groups. Regarding photocatalytic activity, Sn-doped TiO2 samples (TiSn3) were nearly four times higher than undoped samples. This obvious beneficial effect could be attributed to high surface area, optimal crystalline phase and surface state modifications. [ABSTRACT FROM AUTHOR]