Stable loading of MOF-derived carbon skeleton encapsulated Ni and BiOBr on carbonized cellulose fibers for fabricating high-performance and recyclable photocatalytic paper

The highly dispersed small-size metal co-catalysts can effectively improve the photocatalytic efficiency of semiconductor photocatalysts by separating photogenerated electrons and enriching active sites. However, this system tends to aggregate in the absence of carrier, resulting in the decrease of active sites. Here, MOF-derived carbon skeleton (MDCS) encapsulated Ni nanoparticles (Ni@MDCS) and BiOBr was loaded onto carbonized cellulose fibers (CCF) with the help of polydopamine (PDA) to construct high-performance and recyclable photocatalytic paper for photocatalytic degradation of organic dyes in water. The characterization results showed that MDCS promoted good dispersion of Ni nanoparticles and provided sufficient active sites. And Ni@MDCS as a co-catalyst accelerated the separation of photogenerated carriers in BiOBr. The PDA improved the loading state of Ni@MDCS on CCF and converted into N-doped C in the carbonization process for further increasing the transfer efficiency of photogenerated electrons. In the composite paper, the stable loading of Ni@MDCS/BiOBr hybrid on CCF improved the dispersion and reusability of photocatalyst. The degradation rate of rhodamine B on CCF/PDA-C/Ni@MDCS/BiOBr paper was as high as 94.6 % after 60 min visible light irradiation, which was about 2.5 times higher than that of CCF/BiOBr paper. During 10 cycles, CCF/PDA-C/Ni@MDCS/BiOBr paper maintained high photocatalytic efficiency and good structural stability. This study provides a new way for developing high-performance and recyclable photocatalytic paper.

A mesoporous Mo and N Co-doped TiO2 nanocomposite with enhanced photocatalytic efficiency

This study reports the synthesis of a mesoporous Mo and N codoped anatase TiO2 nanocomposite with many oxygen vacancies using a simple one-step hydrothermal method and subsequent calcination treatment. Both Mo and N were effectively co-incorporated into the anatase phase of TiO2 without MoOx phase segregation. The codoped catalyst demonstrated a mesoporous architecture with a surface area of 107.48 m2 g-1 and a pore volume of 0.2974 cm3 g-1. X-ray photoelectron spectroscopy confirmed that both Mo and N dissolved in the TiO2 lattice and created induced oxygen vacancies. The interaction of the dopants (Mo and N) and oxygen vacancies clearly affected TiO2 crystal formation. Photocatalytic performance of the nanocomposite was investigated in terms of the decomposition of methyl orange at a concentration of 50 mg L-1 in an aqueous solution. The results revealed a significant methyl orange degradation of up to 99.6% after 30 min irradiation under a UV light. The impressive performance of the nanocomposite is assigned to the synergetic effect of important factors, including the co-doping of metallic (Mo) and non-metallic (N) elements, oxygen vacancy defects, bandgap, crystallite size, mesoporous structure, and BET surface area.

Effect of bismuth doping on the crystal structure and photocatalytic activity of titanium oxide

The doping of TiO2 with metals and non-metals is considered one of the most significant approaches to improve its photocatalytic efficiency. In this study, the photodegradation of methyl orange (MO) was examined in relation to the impact of Bi-doping of TiO2. The doped TiO2 with various concentrations of metal was successfully synthesized by a one-step hydrothermal method and characterized using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and UV-vis spectroscopy. The XRD results revealed that the anatase phase, with an average crystallite size of 16.2 nm, was the main phase of TiO2. According to the anatase texture results, it was found that the doping of TiO2 increased the specific surface area for Bi2O3@TiO2 without a change in the crystal structure or the crystal phase of TiO2. Also, XPS analysis confirmed the formation of Ti4+ and Ti3+ as a result of doping with Bi. The activities of both pure TiO2 and Bi-doped TiO2 were tested to study their ability to decolorize MO dye in an aqueous solution. The photocatalytic degradation of MO over Bi2O3@TiO2 reached 98.21%, which was much higher than the 42% achieved by pure TiO2. Doping TiO2 with Bi increased its visible-light absorption as Bi-doping generated a new intermediate energy level below the CB edge of the TiO2 orbitals, causing a shift in the band gap from the UV to the visible region, thus enhancing its photocatalytic efficiency. In addition, the effects of the initial pH, initial pollutant concentration, and contact time were examined and discussed.

Ambient Ammonia Synthesis via Nitrate Electroreduction in Neutral Media on Fe3O4 Nanoparticles-decorated TiO2 Nanoribbon Array

Electrochemical nitrate (NO₃^-) reduction is a potential approach to produce high-value ammonia (NH₃) while removing NO₃^- pollution, but it requires electrocatalysts with high efficiency and selectivity. Herein, we report the development of Fe₃O₄ nanoparticles decorated TiO₂ nanoribbon array on titanium plate (Fe₃O₄@TiO₂/TP) as an efficient electrocatalyst for NO₃^--to-NH₃ conversion. When operated in 0.1 M phosphate-buffered saline and 0.1 M NO₃^-, such Fe₃O₄@TiO₂/TP achieves a prominent NH₃ yield of 12394.3 μg h^-1 cm^-2 and a high Faradaic efficiency of 88.4%. In addition, it exhibits excellent stability during long-time electrolysis.

Enhanced photoactive performance of three-layer structured Ag/Cu2O/TiO2 composites with tunable crystal microstructures

Ag particle-decorated Cu2O/TiO2 composite films effectively photodegrade MO solution under irradiation.

Modulation of titania nanoflower arrays transformed from titanate nanowire arrays to boost photocatalytic Cr(vi) detoxification

The integration of the N/S co-doping, anatase/rutile junction construction, and morphology regulation of TiO2 arrays is achieved by a simple method to improve photocatalytic activity.

Enhanced isopropanol sensing of coral-like ZnO-ZrO2 composites

Both p-type ZrO₂ and n-type ZnO are widely adopted oxides towards trace gas detections; however, their combinations to achieve an enhanced gas sensing performance are rarely reported. Herein, we adopted a simple solution combustion technique to synthesize ZnO-ZrO₂ composites for isopropanol sensing. The one-step combustion achieved coral-like macro/mesoporous hierarchical architectures. It is found that, when the Zr/Zn molar ratio is less than 0.02, all Zr atoms were doped into ZnO crystallites; whilst ZrO₂ appeared when the ratio is beyond 0.03. When utilized to detect trace isopropanol in air, the response increases linearly with the increasing concentration of the target gas in the range of 10-1000 ppm. At the optimal operation temperature of 350 °C, the largest slope (0.18 ppm^-1) is recorded for the ZnO-ZrO₂ composite with a Zr/Zn molar ratio of 0.04 and the slope is 23 times that of pure ZnO (0.0078 ppm^-1). It exhibits also a fast response time and recovery time of 19 s and 8 s, respectively, under 100 ppm isopropanol. The impressive gas sensing property can be contributed to both the macro-/mesoporous structure, which facilitates an intimate contact between the target gas and the sensing site, and the p-n junction induced built-in electric field, which favors the charge separation.

Photocatalytic properties of hybrid materials based on a multicharged polymer matrix with encored TiO2 and noble metal (Pt, Pd or Au) nanoparticles

In this study, we report a synthesis of new nanocomposites, wherein TiO₂ is introduced into multicharged polymeric matrix and covered with noble metals (Pt, Pd or Au) for the photocatalytic application.

High-throughput HSE study on the doping effect in anatase TiO2

Systematic study on the doping effects of anatase TiO₂ doped with 40 kinds of elements by high-throughput HSE06 calculations.

Sheet-on-belt branched TiO2(B)/rGO powders with enhanced photocatalytic activity

TiO2(B) is usually adopted to construct phase junctions with anatase TiO2 for applications in photocatalysis to facilitate charge separation; its intrinsic photocatalytic activity, especially when in the form of one- or three-dimensional nanostructures, has been rarely reported. In this study, a sheet-on-belt branched TiO2(B) powder was synthesized with the simultaneous incorporation of reduced graphene oxide (rGO). The monophase, hierarchically nanostructured TiO2(B) exhibited a reaction rate constant 1.7 times that of TiO2(B)/rGO and 2.9 times that of pristine TiO2(B) nanobelts when utilized to assist the photodegradation of phenol in water under UV light illumination. The enhanced photocatalytic activity can be attributed to the significantly increased surface area and enhanced charge separation.

Structural, electrical and optical properties of epitaxial Ta-doped titania films by MOCVD

Epitaxial Ta-doped TiO₂ films deposited via MOCVD were found to exhibit much improved electrical properties compared to the intrinsic TiO₂.

In Situ Fabrication of Hierarchically Branched TiO2 Nanostructures: Enhanced Performance in Photocatalytic H2 Evolution and Li-Ion Batteries

1D branched TiO₂ nanomaterials play a significant role in efficient photocatalysis and high-performance lithium ion batteries. In contrast to the typical methods which generally have to employ epitaxial growth, the direct in situ growth of hierarchically branched TiO₂ nanofibers by a combination of the electrospinning technique and the alkali-hydrothermal process is presented in this work. Such the branched nanofibers exhibit improvement in terms of photocatalytic hydrogen evolution (0.41 mmol g^-1 h^-1 ), in comparison to the conventional TiO₂ nanofibers (0.11 mmol g^-1 h^-1 ) and P25 (0.082 mmol g^-1 h^-1 ). Furthermore, these nanofibers also deliver higher lithium specific capacity at different current densities, and the specific capacity at the rate of 2 C is as high as 201. 0 mAh g^-1 , roughly two times higher than that of the pristine TiO₂ nanofibers.

Photocatalytic decomposition of Rhodamine B on uranium-doped mesoporous titanium dioxide

Mesoporous uranium-doped TiO₂ anatase materials were studied to determine the influence of U-doping on the photocatalytic properties for Rhodamine B (RhB) degradation.

Solution Combustion Synthesis of Nanoscale Materials

Solution combustion is an exciting phenomenon, which involves propagation of self-sustained exothermic reactions along an aqueous or sol-gel media. This process allows for the synthesis of a variety of nanoscale materials, including oxides, metals, alloys, and sulfides. This Review focuses on the analysis of new approaches and results in the field of solution combustion synthesis (SCS) obtained during recent years. Thermodynamics and kinetics of reactive solutions used in different chemical routes are considered, and the role of process parameters is discussed, emphasizing the chemical mechanisms that are responsible for rapid self-sustained combustion reactions. The basic principles for controlling the composition, structure, and nanostructure of SCS products, and routes to regulate the size and morphology of the nanoscale materials are also reviewed. Recently developed systems that lead to the formation of novel materials and unique structures (e.g., thin films and two-dimensional crystals) with unusual properties are outlined. To demonstrate the versatility of the approach, several application categories of SCS produced materials, such as for energy conversion and storage, optical devices, catalysts, and various important nanoceramics (e.g., bio-, electro-, magnetic), are discussed.