JOURNAL OF CATALYSIS
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2022
·
IF 8.047
Wen Xu,Xiaoshu Wang,Weilong Hou,Kang Tang,Xinqing Lu,Yijing Gao,Rui Ma,Yanghe Fu,Weidong Zhu
Although the titanosilicate zeolite catalyzed one-pot oxidative hydration of ethylene with hydrogen peroxide (H 2 O 2 ) to ethylene glycol (EG) takes advantages of step-saving and facile operation, both H 2 O 2 utilization efficiency and EG yield are relatively low. In the present work, Sn-doped Ti-MWW zeolites, named Sn-Ti-MWW, were developed for this oxidative hydration, showing the much higher H 2 O 2 utilization efficiency and EG yield, compared to Ti-MWW. The extensive characterizations of Sn-Ti-MWW zeolites, in combination with Density Functional Theory (DFT) calculations, verify that the doping of Sn into Ti-MWW leads to the higher electropositivity of the Ti species, resulting in the stronger acidity of the zeolite, which is helpful to the H 2 O 2 utilization and EG production. In addition, although the catalyst deactivation is observed due to the deposition of the bulky byproducts onto the active sites and/or into the zeolite micropores, the simple calcination of the used catalyst readily restores its catalytic activity. Therefore, it is anticipated that the developed Sn-Ti-MWW catalyst might be applicable in the one-pot oxidative hydration of ethylene with H 2 O 2 to EG industrially.
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高影响因子
CHEMOSPHERE
·
2023
·
IF 8.8
Hoang Nguyen Tien,Fredrick M. Mwazighe
In this work, a novel La-doped βPbO 2 (Ti/SnO 2 –Sb/La-βPbO 2 ) was prepared using electrodeposition method and applied to the degradation of prednisolone (PRD), 8-Hydroxyquinoline (8-HQ), and other typical organic pollutants. Compared with the conventional electrode Ti/SnO 2 –Sb/βPbO 2 , La 2 O 3 doping enhanced oxygen evolution potential (OEP), reactive surface area, stability and repeatability of the electrode. The 10 g L −1 of La 2 O 3 doping exhibited the highest electrochemical oxidation capability of the electrode with [•OH]ss being determined at 5.6 × 10 −13 M. The quenching experiments were conducted to confirm the main oxidizing species (here: •OH) in the electrochemical process. The study showed that the pollutants were removed in the electrochemical (EC) process with different degradation rates and indicated that the second-order rate constant of organic pollutants towards •OH ( k OP,•OH ) has a linear relationship with the degradation rate of organic pollutants ( k OP ) in the electrochemical process. Another new finding in this work is that a regression line of k OP,•OH and k OP can be used to estimate k OP,•OH of an organic chemical, which cannot be determined using the competition method. k PRD,•OH and k 8-HQ,•OH were determined to be 7.4 × 10 9 M −1 s −1 and (4.6–5.5) × 10 9 M −1 s −1 , respectively. Compared with conventional supporting electrolyte (like SO 4 2− ), H 2 PO 4 − and HPO 4 2− improved k PRD and k 8-HQ by 1.3–1.6-fold, while SO 3 2− and HCO 3 − inhibited k PRD and k 8-HQ significantly, down to 80%. Additionally, the degradation pathway of 8-HQ was proposed based on the detection of intermediates from GC-MS.
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高影响因子
Crystals
·
2023
·Vol. 14
·期 1
·14
·
IF 2.7
Yufei Zu,Zi Wang,Hongliang Tian,Fan Wu,Lianshen Fu,Jixiang Dai,Jianjun Sha
High-entropy diboride-based (MeB2-based) ceramics are promising high-temperature structural materials because of their excellent mechanical properties, high-temperature stability, and oxidation resistance. In order to achieve low-temperature sintering of the high-entropy ceramics, a novel preparation method of high-entropy (Ti,Zr,Nb,Mo,W)B2-SiC ceramics based on reactive sintering of pre-alloyed solid-solution metals and nonmetals of Si, C, B4C was conducted in the current work. Mechanical alloying behavior of the mixed metal powders, as well as the phase composition, microstructure, mechanical properties, and oxidation behavior of the as-sintered MeB2-SiC ceramic were investigated. The XRD, SEM, and EPMA results indicated that the primary MeB2solid-solution and SiC phases could be successfully formed during reactive sintering at a relatively low temperature of 1650 °C. The as-sintered MeB2-SiC ceramics had a high relative density of 97.8% and high mechanical properties (hardness of 19.74 ± 0.8 GPa, flexure strength of 533 ± 38 MPa, and fracture toughness of 6.01 ± 0.77 MPa·m1/2). Combining the oxidation behavior and microstructure evolution of the oxidation layer, a continuous and relatively dense MeOx-SiO2oxidation layer was gradually formed and covered on the external surface, leading to decelerating oxidation behavior after an oxidation exposure time of 10 min.
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OPTICAL MATERIALS
·
2023
·
IF 3.9
Yuwei Sun,Xin Qi,Chou Chen,Wenyu Liu,Qian Tang,Honghui Teng,Baixiang Ren
In this work, AgI nanoparticles were anchored on decahedron-like MIL-125(Ti) through wet precipitation method, and the photocatalytic activities were analyzed by tetracycline (TC) degradation rates under simulated sunlight. The structures, morphologies, valence bonds, optical absorption properties, charge separation efficiencies of the prepared samples were tested by XRD , SEM, EDS , XPS, UV–Vis DRS and PL spectroscopy. Compared with pure MIL-125(Ti), AgI@MIL-125(Ti) displayed excellent photocatalytic performance on TC degradation. When the mass fraction of AgI in AgI@MIL-125(Ti) was 10 %, AgI@MIL-125(Ti)-10 % displayed the best photocatalytic efficiency, which 96.9 % of TC was removed under simulated sunlight for 30 min. The results of active species trapping experiments and ESR tests showed that the Z-Scheme heterojunction between AgI and MIL-125(Ti) promoted the separation of photogenerated charges. Furthermore, a part of Ag + were reduced to Ag NPs in the process of photocatalytic reaction, which constructed a cross-linking bridge for the charges at the interface of AgI and MIL-125(Ti) and further accelerated the electron transmission. The intermediate toxicity experiments proved that the toxic structures are destroyed in TC solution after MIL-125(Ti)-10 % photocatalytic degradation, and the toxicity of the reaction system was reduced effectively.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2020
·
IF 7.489
Yue Wei,Gang Li,Cong Wang,Hongchen Guo
For solvent-free catalytic oxidations , low efficiency resulted from poor mass transfer and insufficient utilization of active centers remains a tough problem. Herein, we demonstrate a novel hybrid core-shell catalyst (TS@PMO) with an amphiphilic shell and a Ti-surface-enriched mesoporous TiO 2 -SiO 2 (TS) core to address this challenge. Such TS@PMO realizes its amphiphilicity via an ex situ formed periodic mesoporous organosilica (PMO) shell. Simultaneously, by a unique etching effect induced by organic precursor growth on [SiO 4 ] tetrahedra in TS core, active Ti sites are facilely enriched in near-surface layer of core and extra mesoporous cavities are introduced for substrate reservation. When applied for solvent-free epoxidation of methyl oleate (MO) with H 2 O 2 , TS@PMO exhibits remarkably boosted catalytic activity (X = 90.2%) and epoxide selectivity (S = 70.2%), overwhelming the unmodified titanosilicate (X = 63.7%, S = 49.2%) and Ti-containing organosilica (X = 39.8%, S = 25.0%). Such result benefits from an evidently enhanced interphase mass transfer and sufficiently accessible active Ti sites in TS@PMO. On the one hand, amphiphilic PMO shell can efficiently collect hydrophobic substrate and H 2 O 2 , while abundant mesopores in the shell offer open-path for them to access active sites in the core; on the other hand, an increased framework Ti (IV) density and their surface-enrichment in TS core greatly improve the utilization of active Ti sites. This study effectively makes up for the deficiencies of slow mass transfer and insufficient utilization of conventional titanosilicates in biphasic reactions, which paves a new avenue to exploit other hybrid catalysts for high-efficiency solvent-free catalysis.
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高影响因子
Journal of Physical Chemistry C
·
2020
·
IF 4.189
Yefeng Feng,Furong Zhou,Maolin Bo,Yuehao Huang,Qihuang Deng,Cheng Peng
High dielectric constant and breakdown strength are crucial for high-energy-density polymer/ceramic composites. Anatase-TiO2 with low dielectric constant and V2C MXene with high work function are not satisfactory fillers. In the present work, V2C–TiO2 hybrid filler was in situ synthesized, followed by fabricating poly(vinylidene fluoride) (PVDF)/V2C–TiO2 composites via solution cast. Compared with PVDF/TiO2 and PVDF/V2C composites, PVDF/V2C–TiO2 composites have an improved high dielectric constant, depressed low dielectric loss, and maintained high breakdown strength. High overall electric traits are ascribed to the synergy of conductive V2C and semiconductive TiO2. Outer and inner surfaces of V2C were ornament-combined by anatase-TiO2 particles having surface point defects as electron traps, contributing to low interface leakage conduction. Through density functional theory (DFT) calculations, nontypical V–F–Ti-bonding-induced dipole enhancement and Fermi-level (EF) overlapping-induced high electron localization mechanisms improve the dielectric response. Ternary composite with 10 wt % hybrid filler exhibits a dielectric constant of ∼99, a dielectric loss of ∼0.24 at 1 kHz, and a breakdown strength of ∼189 MV/m. This work might enable large-scale preparation of promising polymer/MXene composite dielectrics.
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高影响因子
CHEMOSPHERE
·
2020
·
IF 5.778
Jiawei Lei,Pingzhou Duan,Weijun Liu,Zhirong Sun,Xiang Hu
Due to the potential threatening of antibiotics in aqueous environment, a novel electro-oxidation (EO) — electro-Fenton (EF) —persulfate (PS) system with the addition of peroxydisulfate and Fe 2+ was installed for the degradation of cefotaxime. Ti/CNT/SnO 2 –Sb–Er with an ultra-high oxygen evolution potential (2.15 V) and enhanced electrocatalytic surface area was adopted as anode. The OH production and electrode stability test demonstrated great improvement in the electrochemical performances. Ni@NCNT cathode was tested with higher H 2 O 2 generation by the presence of nitrogen functionalities due to the acceleration of electron transfer of O 2 reduction. Experiment results indicated CNT and ErO 2 modification increased the molecular and TOC removal of cefotaxime. Coupling processes of EO-EF and EO-PS both resulted in shorter electrolysis time for complete cefotaxime removal, however, the mineralization ability of EO-PS process was lower than EO-EF, which might result from the immediate vanishing of PS. Thus, a further improved treatment EO-EF-PS system achieved an 81.6% TOC removal towards 50 mg L −1 cefotaxime after 4 h electrolysis, under the optimal working condition Fe 2+ = PS = 1 mM. The influence of current density and initial concentration on the performance of all processes was assessed. Methanol and tert-butanol were added in the system as OH and SO 4 − scavengers, which illustrating the mechanism of EO-EF-PS oxidizing process was the result of the two free radicals. Major intermediates were deduced and the degradation pathway of cefotaxime was analyzed. This research provides a potential coupling process with high antibiotic removal efficiency and effective materials for practical uses.
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高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2021
·
IF 5.302
Yongchang Guo,Ying Zhang,Mathieu Allix,Shaowei Feng,Hong Sun,Cécile Genevois,Emmanuel Véron,Jianqiang Li
Pyrochlore-based glass-ceramics are attracting attention as a promising host material for immobilizing minor actinide in high-level wastes. However, the loading capacity of pyrochlore-based materials for actinide elements is to be improved, and only conventional synthetic approaches of powder sintering and glassy bulk crystallization were reported. Here, new (La,Y) 2 (Zr,Ti) 2 O 7 pyrochlore-based glass-ceramics were subtly designed and successfully prepared through a rapid melting and solidification process. The solidification behavior of samples with different cooling rates was investigated, the dense and crack-free (La,Y) 2 (Zr,Ti) 2 O 7 pyrochlore-based glass-ceramics were prepared at the cooling rate of 500 °C/s (within 1.5 s). The present amorphous La 2 O 3 -TiO 2 -Al 2 O 3 phase demonstrates the outstanding thermal stability compared with the currently used borosilicate glass for high-level waste immobilization due to the lack of conventional glass-forming components. The results show the great feasibility of this novel synthesis route for glass-ceramics by direct solidification and its good potential for immobilizing high-level wastes.
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WATER RESEARCH
·
2019
·
IF 7.913
Dongni Sun,Xiaoting Hong,Keming Wu,K.S. Hui,Yingying Du,K.N. Hui
Electro-oxidation using RuO 2 –IrO 2 /Ti plate anode and electrocoagulation using iron plate anode were widely applied to remove ammonia and phosphate in an aquatic environment, respectively. In this work, we designed magnetically bound ZVI microparticles on RuO 2 –IrO 2 /Ti plate as a composite electrode for the simultaneous removal of ammonia and phosphate from aqueous solution via combined EO and EC (EO/EC) processes. We present a series of experiments to study such simultaneous removal under an electric field via the EO/EC process. In the electrochemical unit, mZVI-RuO 2 -IrO 2 /Ti, mZVI-graphite, and RuO 2 –IrO 2 /Ti electrodes were used as anodes. The influence of applied voltage, initial pH, zero-valent iron dosage, reaction temperature, and organic compounds on the EO/EC process was also examined. Ammonia and phosphate could be completely removed at an applied voltage of 10 V, pH of 7, zero-valent iron dosage of 0.1 g, and reaction temperature of 35 °C using mZVI-RuO 2 -IrO 2 /Ti anode when influent ammonia and phosphate concentrations is 200 and 100 mg L −1 . Ammonia degradation was consistent with pseudo-zero-order kinetic model. The characterization was analyzed by scanning electron microscope-energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Hence, the mZVI-RuO 2 -IrO 2 /Ti electrode can be used for efficient simultaneous removal of ammonia and phosphate.
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高影响因子
MICROPOROUS AND MESOPOROUS MATERIALS
·
2019
·
IF 4.182
Xiaohuan Qi,Tianquan Lin,Shaoning Zhang,Jijian Xu,Huimin Zhang,Fangfang Xu,Fuqiang Huang
Nitrogen-doped hierarchical porous hard carbon (NPC) that are capable of high N content, high specific surface area and high chemical stability has the potential to be a promising electrode material for energy storage application. Here we report a N-doped hierarchical porous hard carbon via a facile Ti-peroxy initiated in-situ polymerization of p -phenylenediamine. Ti-peroxy can also serve as a hard template to manipulate the formation of hierarchical porous. This nitrogen-doped hierarchical porous hard carbon has advantages of high N-content (7.2 at. %) and high surface area (1515 m 2 g −1 ), displaying a specific capacitance of 360 F g −1 and an extraordinary cycling stability above 98% after 30,000 cycles.
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Catalysis Science & Technology
·
2018
·Vol. 8
·期 7
·1936-1944
·
IF 5.365
Zhongmin Liu,Yongchuan Wu,Jitao Chen,Yaru Li,Jingyu Zhao,Kaihua Gao,Ping Na
A bifunctional cake-like TiO2 was successfully synthesized via calcination of MIL-125(Ti) at a suitable temperature by a one-step method and was applied for As(III) removal by simultaneous photocatalytic oxidation and adsorption. The as-synthesized samples were characterized by XRD, TGA/DSC, SEM, TEM, N2 adsorption–desorption isotherms, PL spectra, photocurrent, FTIR and XPS. The effects of calcination temperature on the specific surface areas of the samples, transformation of the TiO2 crystal phase and properties of As(III) removal were investigated. The results showed that higher calcination temperature resulting in a lower specific surface area and more transformations of the TiO2 crystal phase from anatase to rutile. The TiO2 calcined at 380 °C (MIL-125(Ti)-380 °C) exhibited excellent properties for As(III) removal, including photocatalytic oxidation of As(III) and simultaneous adsorption of the generated As(V). In addition, MIL-125(Ti)-380 °C could be reused at least four times without significant reduction in the photocatalytic oxidation and adsorption performances. The excellent photocatalytic oxidation and adsorption abilities of MIL-125(Ti)-380 °C can be attributed to the synergistic effects of strong photogenerated electron–hole separation and high specific surface area. The bifunctional cake-like TiO2 provides a wonderful strategy to remove As(III) completely from contaminated water using a single step.
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RSC Advances
·
2015
·Vol. 5
·期 25
·19601-19612
·
IF 3.84
Tigang Duan,Ye Chen,Qing Wen,Ying Duan
Sb-doped SnO2 electrode was fabricated by the one-step pulse electro-codeposition method, and was modified through either cerium dioxide nanoparticle (nano-CeO2) or cerium ion doping. The results showed that the effects of nano-CeO2 doping and cerium ion doping are quite different. Nano-CeO2 doping shrinks the unit cell volume, improves the degree of crystallinity and refines crystalline grains, while cerium ion doping expands the volume and deteriorates the crystallinity. Nano-CeO2 doping mitigates the surface antimony enrichment and promotes the complete oxidation of antimony so that the majority of antimony oxidation states exist as the Sb5+ state, but cerium ion doping aggravates the enrichment and increases the Sb3+ content. Electrochemical phenol degradation showed that the Ti/Sb–SnO2–CeO2 electrode has a higher degradation efficiency and its kinetic rate constant is 1.46 times as much as that of Ti/Ce–Sb–SnO2. Besides, due to the compact active layer of Ti/Sb–SnO2–CeO2 protecting the titanium substrate from passivation, the accelerated service lifetime of Ti/Sb–SnO2–CeO2 is prolonged, which is 1.28 times as long as that of Ti/Ce–Sb–SnO2.
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