Synergistic Mechanism of Rare-Earth Modification TiO2 and Photodegradation on Benzohydroxamic Acid

Rare earth elements are plentiful in Gannan area, China, and there is a large amount of wastewater from all kinds of mines. In this paper, rare-earth modification TiO2 composites (RE/TiO2, RE = La, Ce, Gd, Yb) was studied by theory computation and experimental performance. The prepared RE/TiO2 was investigated for the degradation of benzohydroxamic acid (BHA) as a typical residual reagent in wastewater from beneficiation. The crystallinity, morphology, specific surface area, light absorption, and composition of compound were investigated by various techniques. As a result of computation and experimentation, four different electron configurations of rare earth all retained the anatase phase of TiO2 and reduced the band gap of TiO2 to some degree compared with pure TiO2. Different rare-earth elements and calcination temperatures resulted in different removal effects on BHA. The optimum doping contents were 0.75% (500 °C), 0.20% (500 °C), 0.70% (500 °C) and 0.50% (450 °C) for La, Ce, Gd, Yb respectively. All the RE/TiO2 composites studied in this research still possessed good photoactivity after four runs, which supports the theoretical and practical basement for the photocatalytic treatment of mining and metallurgy wastewater

The activity and selectivity of catalytic peroxide oxidation of chlorophenols over Cu-Al hydrotalcite/clay composite

Liquid phase catalytic oxidation of chlorophenols (CPs) was carried out over Cu-Al hydrotalcite/clay composite at ambient temperature and pressure using hydrogen peroxide as oxidant. The results showed that the catalyst had high catalytic activity, with complete oxidation of 4-CP within 40 min at 40 degrees C. The content and position of chlorine on the aromatic ring had significantly different effects on the oxidation rate of CPs, with the rate sequence of phenol > monochlorophenol (MCP) > dichlorophenol (DCP) > trichlorophenol (TCP), 3-CP > 2-CP > 4-CP. and 3,5-DCP > 3,4-DCP > 2,5-DCP > 2,4-DCP > 2,6-DCP. This was ascribed to the interactions among sigma-electron withdrawing conductive effect, pi-electron donating conjugative effect, and steric hindrance effect of chlorine. It was evidenced that the catalytic peroxide oxidation of CPs in the first step was selective and rate-limiting, where chlorinated 1,4-benzoquinones formed. (C) 2011 Elsevier Inc. All rights reserved.Liquid phase catalytic oxidation of chlorophenols (CPs) was carried out over Cu-Al hydrotalcite/clay composite at ambient temperature and pressure using hydrogen peroxide as oxidant. The results showed that the catalyst had high catalytic activity, with complete oxidation of 4-CP within 40 min at 40 degrees C. The content and position of chlorine on the aromatic ring had significantly different effects on the oxidation rate of CPs, with the rate sequence of phenol > monochlorophenol (MCP) > dichlorophenol (DCP) > trichlorophenol (TCP), 3-CP > 2-CP > 4-CP. and 3,5-DCP > 3,4-DCP > 2,5-DCP > 2,4-DCP > 2,6-DCP. This was ascribed to the interactions among sigma-electron withdrawing conductive effect, pi-electron donating conjugative effect, and steric hindrance effect of chlorine. It was evidenced that the catalytic peroxide oxidation of CPs in the first step was selective and rate-limiting, where chlorinated 1,4-benzoquinones formed. (C) 2011 Elsevier Inc. All rights reserved

Stable Structure and Fast Ion Diffusion: A Flexible MoO₂@Carbon Hollow Nanofiber Film as a Binder-Free Anode for Sodium-Ion Batteries with Superior Kinetics and Excellent Rate Capability

Designing innovative anode materials that exhibit excellent ion diffusion kinetics, enhanced structural stability, and superior electrical conductivity is imperative for advancing the rapid charge–discharge performance and widespread application of sodium-ion batteries. Hollow-structured materials have received significant attention in electrode design due to their rapid ion diffusion kinetics. Building upon this, we present a high-performance, free-standing MoO2@hollow carbon nanofiber (MoO2@HCNF) electrode, fabricated through facile coaxial electrospinning and subsequent heat treatment. In comparison to MoO2@carbon nanofibers (MoO2@CNFs), the MoO2@HCNF electrode demonstrates superior rate capability, attributed to its larger specific surface area, its higher pseudocapacitance contribution, and the enhanced diffusion kinetics of sodium ions. The discharge capacities of the MoO2@HCNF (MoO2@CNF) electrode at current densities of 0.1, 0.2, 0.5, 1.0, 2.0 and 5.0 A g−1 are 195.55 (155.49), 180.98 (135.20), 163.81 (109.71), 144.05 (90.46), 121.16 (71.21) and 88.90 (44.68) mAh g−1, respectively. Additionally, the diffusion coefficients of sodium ions in the MoO2@HCNFs are 8.74 × 10−12 to 1.37 × 10−12 cm2 s−1, which surpass those of the MoO2@CNFs (6.49 × 10−12 to 9.30 × 10−13 cm2 s−1) during the discharging process. In addition, these prepared electrode materials exhibit outstanding flexibility, which is crucial to the power storage industry and smart wearable devices

Synthesis and optical-electronic properties of a novel star-shaped benzodithiophene molecule

Benzodithiophene (BDT)-based star-shaped molecule (12TBDT) was synthesized by Stille coupling reactions. The star-shaped molecule shows high decomposition temperature (447 °C), low-lying HOMO level (-5.52 eV), and wide UVvis absorption between 300 and 530nm (Eg= 2.36 eV). DFT results show that the electron density of the HOMO and LUMO are localized on the thiophene and BDT groups. To the best of our knowledge, this is one of the earliest reports on star-shaped benzodithiophene molecules.</p

Improved open-circuit voltage of benzodithiophene based polymer solar cells using bulky terthiophene side group

Terthiophene, including one α-α and one branching α-β connection of the thiophene units, is introduced as benzodithiophene (BDT) side chain to build a novel two-dimensional (2D) conjugated BDT block. By copolymerizing this BDT block with three electron acceptors (DTTz (bis(thiophene-2-yl)-tetrazine), DPP (diketopyrrolopyrrole), DTffBT (4,7-bis(4-hexylthienyl)-5,6-difluoro-2,1,3-benzothiadiazole)) and one electron donor (TTT (2,5-Di(2-thienyl)thiophene)), four terthiophene side-chained benzodithiophene based copolymers were synthesized. Due to the difference in electron affinity among DTTz, DPP, DTffBT and TTT, these four polymers show different UV-vis absorption spectra and optical band gaps (1.3-2.0 eV), while fortunately they all remain deep highest occupied molecular orbital (HOMO) energy levels (-5.3 to 5.6 eV) which is very favorable to high open-circuit voltage (Voc) polymer solar cells (PSCs). By comparing the photovoltaic properties with polymers which have same backbone but do not have the bulky 2D side group in the literatures, our polymer solar cells devices show higher Voc. Especially for PQ3 (a copolymer of benzodithiophene and diketopyrrolopyrrole), the donor photon energy loss (Eg-eVoc) is 0.51 eV which is almost the lowest value achieved by the researchers. It can be concluded that: the bulky terthiophene side group helps to improve Voc of the PSCs devices. The overall performance of solar cells devices is correlated with the molecule conformation, polymer hole mobility and polymer/PCBM blend film morphology.</p