INTERNATIONAL JOURNAL OF POLYMER ANALYSIS AND CHARACTERIZATION
·
2013
·
IF 1.233
Shun
Ping Wang,Xiao
Deng Yang,Qing
Quan Bai,Tian
Duo Li
A comparative kinetic study of the urethane reactions of phenyl isocyanate and 1,2-, 1,3-, and 1,4-butanediol was carried out in dichloromethane solution with zirconium (IV) acetylacetonate as catalyst. In situ FT-IR was used to follow the kinetics of the reactions at a constant temperature of 15°–30°C. The rate constants for the reaction of the primary hydroxyl group and the secondary hydroxyl group were calculated as k
prim and k
sec, respectively. Analysis of the second-order rate constants of these systems indicated that k
prim follows 1,2-butanediol >1,3-butanediol >1,4-butanediol. The ratio of k
prim/k
sec in 1,2-butanediol was the highest and the order followed was the same as with the reaction rate. Activation energies and Eyring parameters were also determined for the urethane reaction of butanediols.
研究领域:
化学
·
材料科学
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JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2019
·Vol. 103
·期 4
·2663-2673
·
IF 3.094
Boo-Hyun Choi,Dae-Su Kim,Ku-Tak Lee,Bum-Joo Kim,Jeong-Su Kang,Sahn Nahm
Hydrothermally synthesized ZnS nanopowders comprising small and large particles were used to synthesize ZnS ceramics. Small particles (200 nm) existed in the gaps between the large particles (0.7 μm) and assisted the densification of the ZnS ceramics. ZnS ceramics sintered at low temperatures (<1000°C) exhibited small grains with large grain-boundary areas that provided diffusion paths for carbon ions from the graphite mold, resulting in carbonate absorption bands. ZnS ceramics sintered at high temperatures (≥1000°C) for a long time (≥2.0 hours) exhibited a dense microstructure with very large grains (>500 μm). The ZnS liquid phase, which was formed at approximately 980°C, assisted the densification and grain growth of the ZnS ceramics. A 3.0-mm-thick ZnS ceramic sintered at 1000°C for 16 hours showed a high Knoop hardness (321 kgf/mm 2 ) and a high transmittance of 71% in the wavelength range 6.0-12 μm without carbonate absorption bands.
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NANOTECHNOLOGY
·
2018
·Vol. 29
·期 40
·405705
·
IF 3.404
Junnan Li,Ziwei Pan,Kebin Zhou
Developing efficient catalysts to accelerate the rate of oxygen evolution reaction (OER) is critical for photocatalytic water-splitting. In this work, metallic Ir, IrOx(OH)y, and core–shell Ir@IrOx(OH)y were synthesized and employed as OER catalysts for photocatalytic water oxidation. It was found that the Ir@IrOx(OH)y core–shell heterostructure catalyst showed the best photocatalytic performance among these three catalysts, with the oxygen evolution rate as high as 59.63 mmol g−1 h−1. Detailed investigations revealed that the excellent photocatalytic activity of Ir@IrOx(OH)y could be attributed to both the outstanding intrinsic activity of IrOx(OH)y shell and the efficient electron transfer between the photosensitizer and catalyst.
研究领域:
材料科学
·
能源化学
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CATALYSIS TODAY
·
2018
·
IF 4.667
Xiao Dong,Peng Zheng,Ai-Guo Zheng,Hui-Feng Li,Guo-Fu Xia,Ming-Feng Li,Ren-Yang Zheng,Bo-Qing Xu
Pt-Co/SiO 2 and Pt-Ir-Co/SiO 2 catalysts were prepared via galvanic replacement (GR) and employed for the hydrogenolytic ring-opening of methylcyclopentane (MCP). Selective deposition of the noble metals at the less expensive Co nanoparticle (NP) surface by GR greatly enhanced the utilization efficiency of the more active Pt or Pt and Ir atoms for the selective catalysis to the ring-opening reaction of MCP, as justified by comparison with catalysts from conventional impregnation preparation. The chemistry of GR was quantitatively studied by comprehension of the composition changes both in the preparation solution and in the solid samples. The structural features of GR catalysts were characterized as highly dispersed Pt or Pt and Ir clusters selectively deposited on Co NP surface. Compared to their counterparts from impregnation preparation, the GR catalysts showed much higher mass-specific activity normalized by overall noble metal loading (MSA NM ), due to the significantly enhanced utilization efficiency of Pt or Pt and Ir. In addition, the trimetallic Pt-Ir-Co/SiO 2 catalyst showed a distinctly higher MSA NM than the bimetallic Pt-Co/SiO 2 and Ir-Co/SiO 2 ones. This observation features a synergy between the highly dispersed Pt and Ir clusters in the catalysis, besides the enhanced noble metal utilization efficiency. Our catalytic data seem to suggest that a dicarbene mechanism was prevailing over the GR catalysts for the ring-opening reaction of MCP.
研究领域:
催化化学
·
材料科学
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CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Jiabin Ji,Congyun Zhang,Xianfeng Yang,Fanxin Kong,Chuanqiang Wu,Huimei Duan,Dongjiang Yang
Improving the sulfur-resistance of low-temperature methane combustion catalysts is great important for industrial applications. Electronic engineering of catalyst active sites is effective in tuning the catalytic performance. Herein, IrPt 0.5 /TiO 2 catalysts with electron-rich Ir structures modulated by Pt exhibit excellent low temperature sulfur-resistance towards methane combustion. The integrated characterization coupled with density functional theory calculations reveal that the strong electronic interaction between Ir and Pt induces the formation of electron-rich Ir structures. The electron-rich Ir structures with more defective oxygen vacancy and better redox ability greatly boost the adsorption and activation of O 2 while suppress SO 2 adsorption on the catalyst surface, leading to excellent sulfur tolerance towards methane combustion. This work highlights a practical electronic engineering strategy to tune the electron structure of Ir active sites for the development of practical methane oxidation catalysts.
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RENEWABLE ENERGY
·
2023
·
IF 8.7
Yun Zhang,Chuanbiao Zhang,Wenjuan Li,Qiuping Xiao,Fengyuan Jiao,Sen Xu,Yanhua Lan,Yizheng Fu,Chi-Min Shu,Weiguo Cao
Stearic acid provides a basis for developing renewable energy, such as solar energy and biomass energy. A thermogravimetric-infrared spectroscopy (TG-IR) experimental test is conducted to obtain the thermal decomposition progress and the main gaseous products of stearic acid. The result shows that small gaseous products (H 2 O, CO 2 , CO, alkanes, olefins , etc.) are released. Furthermore, the method of reactive molecular dynamics simulation (ReaxFF-MD) is utilized to look into the pyrolysis reaction mechanism of stearic acid. The main pyrolysis products of stearic acid received by ReaxFF-MD are C 2 H 4 , H 2 , C 2 H 2 , CH 4 , H 2 O, CO 2 , and CO, consisting of the result of the TG-IR test. The effect of the simulated system density and temperature on the distribution of main products is also explored. Also, the thermal kinetic analysis is conducted by the initial consumption of stearic acid under different temperatures. The primary reaction mechanism of stearic acid pyrolysis is that the stearic acid molecules dissociate through C–C bonds break to generate C 2 H 4 , CH 4 , C 2 H 2 , C 3 H 6 , and other small molecules and radicals, and a typical reaction mechanism scheme of stearic acid pyrolysis is presented. The results provide a reference for explaining the macroscopic explosion characteristics of dust at the microscopic mechanism level.
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ENVIRONMENTAL TECHNOLOGY
·
2022
·
IF 3.475
Zhen-xing Yang,Wen-yu Xie,Fang-fang Ye,De-hao Li
Electro-catalytic technology is a promising approach for wastewater treatment, owing to its easy operation, minimal generation of secondary pollution, small foot-print and rapid start-up. In this work, the chlorine evolution potential of the Pd-Sn modified ruthenium(Ru)-iridium(Ir) electrode was investigated for the electro-catalytic treatment of high chlorine ammonia-nitrogen wastewater. The effect of reaction conditions on the removal of ammonia-nitrogen, kinetics and apparent activation energy of ammonia-nitrogen removal were studied. The possible denitrification process of high chlorine ammonia-nitrogen wastewater was discussed. The results indicated that the chlorine evolution potential of the Pd-Sn modified Ru-Ir electrode was 1.0956 V(vs. SCE). The electro-catalytic treatment of high chlorine ammonia-nitrogen conformed to zero-order kinetic law, and the apparent activation energy of removal process was 14.089 kJ/mol. With a current was 0.5 A, the removal efficiency of ammonia-nitrogen could achieve 100% at a reaction time of 40 min. Indirect oxidation played an essential role in the electro-catalytic ammonia-nitrogen removal using the Pd-Sn modified Ru-Ir electrode. This paper demonstrated that the electro-catalytic technology was a promising approach for efficiently treating the high chlorine ammonia-nitrogen wastewater.
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ChemistrySelect
·
2022
·Vol. 7
·期 31
·e202201268
·
IF 2.307
Aixiao Fu,Mengqing Sun,Shifeng Jiang,Huanfei Xu,Guoqiang Xu
Graphical Pyrroles are important nitrogen-containing compound. Here, we constructed N, P-doped activated carbon supported Ir to perform the synthesis of pyrroles from alcohols and amino alcohols. The unique performance is attributed to the interaction between Ir and N, P-doped activated carbon. Pyrroles are a significant class of nitrogen-containing heterocyclic compounds and the derivatives. Here, an efficient procedure has been proposed for the loading of Ir on N, P-doped activated carbon to exploit pyrroles are synthesized from alcohols and amino alcohols. And the optimal conversion of 1-phenylethanol is up to 65 % with 2-phenylpyrrole selectivity of 80 %. The good performance is attributed to the interaction between metal Ir and N, P-doped activated carbon, which could also be confirmed from BET and XPS characterizations. What's more, the catalyst could be generally used for a range of reactions to produce pyrroles from alcohols and amino alcohols.
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DALTON TRANSACTIONS
·
2022
·Vol. 51
·期 22
·8832-8839
·
IF 4.569
Yihao Gao,Jie Bai,Tianning Zhou,Yaqiong Gong
In recent years, Co-based metal–organic frameworks (Co-MOFs) have received significant research interest because of their large specific surface area, high porosity, tunable structure and topological flexibility. However, their comparatively weak electrical conductivity and inferior stability drastically restrict the application of Co-MOFs in the synthesis of electrocatalysts. In this study, ZIF-67 was grown on nickel foam by a room temperature soaking method, and then Ir–Co(OH)2@ZIF-67/NF was assembled by a hydrothermal method. The prepared Ir–Co(OH)2@ZIF-67/NF nanosheets exhibit remarkable conductivity, larger electrochemical active surface area and wider electron transport channels. Only ultralow overpotentials of 198 mV, 263 mV, and 300 mV were needed for Ir–Co(OH)2@ZIF-67/NF to reach the current densities of 10 mA cm−2, 50 mA cm−2, 100 mA cm−2, meanwhile, no obvious degradation of the current density at 10 mA cm−2 was observed for about 16 h. This work may provide a promising strategy for developing high-performance MOF-derived materials as electrocatalysts for the OER under alkaline conditions.
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CHEMISTRY-A EUROPEAN JOURNAL
·
2021
·Vol. 28
·期 3
·e202103346
·
IF 5.236
Zhongxian Fan,Jiaen Xie,Tumpa Sadhukhan,Chao Liang,Can Huang,Wenqing Li,Tingxuan Li,Pingyu Zhang,Samya Banerjee,Krishnan Raghavachari,Huaiyi Huang
Graphical Four novel Ir(III) photo-catalysts ( Ir1 – Ir4 ) were synthesized and applied for photocatalytic cancer therapy. Upon blue and green light irradiation, these photocatalysts generated singlet oxygen and induced rapid photo-catalytic oxidation of the cellular coenzymes NAD(P)H. Ir2 triggered promising photo-induced anticancer activity via induction of intracellular redox imbalance and exhibited ideal in vivo photo-induced catalytic anticancer activity. Four photo-catalysts of the general formula [Ir(CO6/ppy) 2 (L)]Cl where CO6=coumarin 6 ( Ir1 – Ir3 ), ppy=2-phenylpyridine ( Ir4 ), L=4′-(3,5-di-tert-butylphenyl)-2,2′ : 6′,2′′-terpyridine ( Ir1 ), 4′-(3,5-bis(trifluoromethyl)phenyl)-2,2′ : 6′,2′′-terpyridine ( Ir2 and Ir4 ), and 4-([2,2′ : 6′,2′′-terpyridin]-4′-yl)-N,N-dimethylaniline ( Ir3 ) were synthesized and characterized. These photostable photo-catalysts ( Ir1 – Ir3 ) showed strong visible light absorption between 400–550 nm. Upon light irradiation (465 and 525 nm), Ir1 – Ir3 generated singlet oxygen and induced rapidly photo-catalytic oxidation of cellular coenzymes NAD(P)H. Ir1 – Ir3 showed time-dependent cellular uptake with excellent intracellular retention efficiency. Upon green light irradiation (525 nm), Ir2 provided a much higher photo-index (PI=793) than the clinically used photosensitizer, 5-aminolevulinicacid (5-ALA, PI>30) against HeLa cancer cells. The observed necro-apoptotic anticancer activity of Ir2 was due to the Ir2 triggered photo-induced intracellular redox imbalance (by NAD(P)H oxidation and ROS generation) and change in the mitochondrial membrane potential. Remarkably, Ir2 showed in vivo photo-induced catalytic anticancer activity in mouse models.
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CHEMISTRY OF MATERIALS
·
2019
·
IF 10.159
Tongtong Yu,Shanpeng Wang,Xiang Zhang,Chenning Li,Jie Qiao,Ning Jia,Bing Han,Sheng-Qing Xia,Xutang Tao
Mid-infrared (MIR) nonlinear optical (NLO) crystals are crucial in generating MIR lasers, which are important in civilian and military applications. Compared to the extensively investigated ternary and quaternary chalcogenide NLO crystals, ternary phosphide crystals have a large nonlinearity coefficient and a wide transparency range. For instance, the well-known ternary chalcopyrite phosphide NLO crystal, ZnGeP2, possesses a large nonlinearity coefficient (deff = 75 pm/V) and a broad transmittance range of 0.75–12 μm. However, its applications in the far-infrared laser range were hindered by its strong absorption near 9 and 10–12 μm. Here, considering that Mn2+ not only makes contributions to large second-harmonic generation (SHG) response but also extends the transparency wavelength range, a new ternary chalcopyrite phosphide crystal, MnSiP2 (MSP), was rationally designed by substituting a II-site metal (Zn or Cd) for Mn in the II-Si-P2 family. In this work, the synthesis and single-crystal growth of MSP were systematically investigated. The theoretical and experimental characterizations demonstrated that MSP exhibits a good balance between strong SHG behavior (6 × AgGaS2) and large laser damage threshold (about 70 MW/cm2). Specifically, the long-wavelength MIR cutoff edge of MSP is 18.2 μm, and the outstanding terahertz (THz) transmittance covers the range of 0.4–2.0 THz, indicating the ultrabroad transparency range. This work may provide a feasible strategy and impel one to search for promising outstanding MIR NLO crystals in the ternary phosphide family.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2024
·
IF 9.4
Xingrui Yu,Chao Xiong,Yichao Liang,Xiantai Zhou,Can Xue
Epoxides are important bulk chemicals, playing irreplaceable role in the chemical industry, but facing serious pollution and low productivity in the production process. Therefore, the development of green and efficient epoxidation of olefins by stable catalysts with low prices is of great significance. In this study, a Mo-MATP catalyst was prepared by modifying Mo(CO)₆ on attapulgite through Si-O bonding. Mo-MATP exhibits excellent performance (99% yield of cyclooctane oxide, CYCO) and stability (80% selectivity of CYCO after 17 cycles), highly tert -butyl hydroperoxide (TBHP) utilization, and extensive substrate scalability. Furthermore, the in-situ Fourier Transform Infrared Spectroscopy (FT-IR), Electron Spin-resonance Spectroscopy (ESR) and High Resolution Mass Spectrometry (HRMS) spectra suggest that TBHP would be activated by Mo-MATP to generate peroxyl radicals, which then oxidize alkenes to their corresponding epoxides. In this study, the stable loading of Mo would largely solve the problem of Mo loss during the catalytic process, thus providing a stable and dispersed Mo active center, enabling the catalyst to possess high catalytic performance and recycling stability.
研究领域:
催化化学
·
绿色化学
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