Search

Abstract: A novel photocatalyst AgAlO2/TiO2 with a p–n heterojunction structure was synthesized through the method that combined sol–gel and ion exchange. The as-synthesized samples were characterized by XRD, SEM and UV–vis. The photocatalytic activity of as-synthesized sample was evaluated and the possible mechanism was discussed. As-synthesized AgAlO2/TiO2 (in mass ratio of 90/10) exhibited remarkably high photocatalytic activity of 97.8% in decomposing formaldehyde under sunlight irradiation for 90min. Our work provided a basic experimental process for AgAlO2/TiO2 heterojunction and explored the connection between p–n heterojunction and photocatalysis, which will possess a broad prospect in terms of the applications in improving indoor air quality. [Copyright &y& Elsevier]

Abstract: This paper reports the synthesis of the VOx–WOy/TiO2-palygorskite composite catalysts via mixed impregnation method. The samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The fibers of palygorskite retained the original morphology upon calcination. The VOx–WOy/TiO2 (VWT) particles were attached on the surface of the palygorskite. The mass ratio of VWT to palygorskite showed an obvious effect on the coating condition of VWT onto the palygorskite, which also affected the catalytic performance. The composites had the highest catalytic activity of 90% to orto-dichlorobenzene (o-DCB) at the mass ratio of 2:1. [Copyright &y& Elsevier]

Uniform CeO2 /TiO2 composite nanoparticles with different Ce/Ti molar ratios have been successfully synthesized via the sol–gel method. The samples were characterized using differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The surface state analysis by means of X-ray photoelectron spectroscopy (XPS) shows that the Ti element mainly exists as a chemical state of Ti4+, while the Ce element exists as a mixture of Ce3+ and Ce4+ oxidation states. The photocatalytic degradation of methyl orange (MeO) in CeO2 /TiO2 suspension was investigated. The results indicate that the CeO2/TiO2 nanocomposites show higher photocatalytic activity than pure TiO2. Photodegradation of MeO can be improved by increasing the Ce/Ti molar ratio in the initial 15 min. [ABSTRACT FROM AUTHOR]

This work provides a new method for fabrication of the flake-like Cu 2 O/TiO 2 nanotubes array (TNA) electrode as a H 2 O 2 sensor. The flake-like Cu 2 O/TNA electrode was successfully constructed by potentiostatic electrodeposition combining subsequent cyclic voltammetry (CV) technology in NaOH solution. The catalytic performance of the sensor was studied in 0.1 M phosphate buffer (PBS, pH = 7.4). It was found that the flake-like Cu 2 O/TNA electrode displayed a good catalytic performance towards the reduction of H 2 O 2 with a response time of 4 s, a wide linear dependence on a concentration of H 2 O 2 from 0.5 mM to 8 mM, a good sensitivity of 412.11 μA cm − 2 mM − 1 and a detection limit of 90.5 μM at a working voltage − 0.40 V (vs. Hg/Hg 2 Cl 2 ). The electrocatalytic mechanism of the flake-like Cu 2 O/TNA electrodes was also proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • A composite electrode was prepared by assembling leaf-like Ag and petal-like Cu 2 O on TiO 2 nanoarray substrate. • The composite electrode can detect ammonia nitrogen in water quickly and accurately. • The concentration range of is 0.1 ∼ 101 μM, and the detection limit is 0.074 μM. • The synergistic action of silver and Cu 2 O improves the sensitivity of ammonia nitrogen detection. In this study, a self-supporting cuprous oxide and Ag modified titanium dioxide nanotubes (Ag/Cu 2 O/TNTs) sensor was constructed by electrochemical method for the ultra-sensitive detection of ammonia nitrogen under neutral conditions. The petal-like "cuprous oxide" and "leaf-like" silver nanoparticles grown on titanium dioxide nanotube arrays can significantly enhance the electrochemical effective area and electrocatalytic performance of the composite electrode. Notably, Ag/Cu 2 O/TNTs sensor was successfully used for the determination of ammonia nitrogen at low concentrations under neutral conditions in the range of 0.1–101 μM with a corresponding detection limit of 0.074 μM. The obtained sensor demonstrated reliable recoveries (97.30 % to 103.8 %) and RSD (1.46 % to 1.83 %) in the analysis of real samples. It provides a fast and accurate method for the detection of ammonia nitrogen at low concentrations in real waters. It is expected to be suitable for the real-time detection because of its excellent immunity to interference, repeatability and stability. [ABSTRACT FROM AUTHOR]

Antimony selenide (Sb 2 Se 3) is a very handy light-absorbing material in photochemical devices based on TiO 2 nanotube arrays (TNT), but it has some problems with anisotropy and agglomeration. Large particles of antimony selenide instead impede photon transport and are susceptible to photocorrosion instability, making it crucial to develop a strategy for the directional growth of rod-shaped Sb 2 Se 3 arrays. Herein, we successfully achieved the deposition of Sb 2 Se 3 inside the tube of TNT by pulsed electrodeposition strategy to obtain the oriented Sb 2 Se 3 nanorod arrays for efficient photoelectron transport. The conductive atomic force microscopy indicates the enhanced electron transfer performance. The UV spectral conclusion shows that the deposition of rod-shaped Sb 2 Se 3 enhances the UV–vis diffuse absorption of TiO 2 , meanwhile, TNT acts as a shell to protect antimony selenide and effectively prevents its photocorrosion phenomenon. Therefore, the photocurrent density of TNT/Sb 2 Se 3 NRs is 6.79 times as that of bare TNT. The Pt/TNT/Sb 2 Se 3 NRs electrode exhibits a photocurrent density of 2.6 mA cm−2 (−0.2 V RHE) and considerable hydrogen evolution performance. In addition, the Surface-Enhanced Raman effect (SERS) originated from this Sb 2 Se 3 array, is first observed, which is expected to reduce the cost of SERS technology. [Display omitted] • Oriented arrays of Sb 2 Se 3 /TiO 2 nanorods facilitate photoelectron transport and separation. • Sb 2 Se 3 extends the absorption utilization of visible light by TiO 2. • TiO 2 used as a shell could protect Sb 2 Se 3 and effectively prevent its photocorrosion phenomenon. [ABSTRACT FROM AUTHOR]

Adjusting Sb 2 Se 3 crystallographic orientation and morphology concurrently on TiO 2 nanotube arrays (TNA) via varying pulse electrodeposition strategy to achieve a great improvement in photoelectrochemical performance. ________________________________________________ [Display omitted] • [2 1 1]-oriented Sb 2 Se 3 arrays was obtained via pulse electrodeposition and space-confined effect of TNA. • [2 1 1]-oriented Sb 2 Se 3 /TNA photoanode generated a photocurrent of 3.02 mA cm−2, 4.1 times more than [2 3 0]-oriented one. • Improved charge separation was due to higher electron mobility along the [2 1 1] orientation. • In situ XPS was used to monitor photoelectron transfer from Sb 2 Se 3 arrays to TNA. Coupling the appropriate light-absorbing materials with titanium dioxide (TiO 2) nanotube arrays (TNA) can significantly enhance the Performance of photoelectrochemical (PEC) devices. Anisotropic antimony selenide (Sb 2 Se 3) is a promising photo-absorber, but optimizing its crystallographic orientation and morphology concurrently is challenging. Herein, we control the growth of Sb 2 Se 3 utilizing the space-confined effect of TNA with varying electrodeposition strategies to regulate the nucleation position. The [2 1 1]-oriented rod-like Sb 2 Se 3 /TNA photoanode prepared by pulse electrodeposition generates a photocurrent of 3.02 mA cm−2 at 1.23 V (versus RHE) in an electrolyte of pH 7, which is ∼4.1- and ∼30.0-time as those of [2 3 0]-oriented octahedron-like Sb 2 Se 3 /TNA and bare TNA photoanodes, respectively. Photoelectron can travel easily along the vertical direction via the covalent bond of (Sb 4 Se 6) n ribbons without the recombination loss along the van der Waals direction due to the optimized Sb 2 Se 3 [2 1 1] orientation and 1D-1D array structure. In situ irradiation X-ray photoelectron spectroscopy is used to directly monitor photoelectron transfer from Sb 2 Se 3 to TNA at the heterojunctions, which ensures the promoted photoelectron separation and extraction in the rod-like Sb 2 Se 3 /TNA photoanode at the positive bias. This work provides a new strategy for optimally orienting anisotropic semiconductors and a fundamental insight into their photoelectron separation for design of efficient photoanodes. [ABSTRACT FROM AUTHOR]

Abstract: Leached talc was used as Si source to synthesize MCM-41 mesoporous silica with huge surface area (1102m2/g) and uniform pore size distribution (2.8nm). Then the synthesized MCM-41 was applied as the host for size-confined tin oxide (SnO2) to produce SnO2/MCM-41 composites. Tin was introduced into the pores of MCM-41 matrix by sol–gel method with SnCl4 ·5H2O as Sn source and citric acid controlling the hydrolysis rate. X-ray diffraction (XRD), high-resolution TEM (HRTEM) and N2 adsorption–desorption measurements confirmed the incorporation of SnO2 nanoparticles inside the pores of the mesoporous host without destroying its integrity. No bulk SnO2 nanoparticles were observed on outer surface of the mesoporous matrix. Furthermore, decrease of pore volume, average pore diameter and BET surface area, and increase of wall thickness proved the existence of SnO2 nanoparticles within the channels of host. The SnO2/MCM-41 composites showed enhanced room-temperature photoluminescence (PL) property with about 8 times of pure SnO2 nanoparticles. [Copyright &y& Elsevier]