ACS Catalysis
·
2024
·
IF 11.3
Xiaohui Leng,Xin Zhou,Lu Ma,Yonghua Du,Ouwen Peng,Zhongxin Chen,Jinhui Pan,Ming-Yu Qi,Jian-Hui Zheng,Yi-Jun Xu,Kian Ping Loh
Visible light induced oxidative C–C and C–N coupling provides a milder alternative to the current synthetic strategies. However, the photochemical C–C coupling of benzylamine and chromoselective C–C/C–N conversion are not widely reported. Herein, we demonstrate that the introduction of indium vacancies in ZnIn2S4 improves the catalytic activity for C–C coupling of benzylamine and imparts a strong chromoselectivity for C–C or C–N coupled products. A high C–C selectivity of ∼80% is achieved with a benzylamine conversion of ∼80%. Mechanistic studies unveil the switchable reaction routes between kinetically favored C–C coupling and thermodynamically favored C–N coupling under specific illumination conditions.
研究领域:
化学
·
材料科学
·
光催化
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Jiangang Chen,Meixia Cai,Ying Liu,Panpan Yang,Jiping Wang
This paper develops a novel adhesive for in-situ joining C/C composites to C/C-SiC composites using a phenolic resin modified with inert fillers (SiC and graphite powders). The primary phase of the reaction bonding joint layer is SiC, which matches the thermal expansion coefficient of the matrix better than metallic phases, making it an improvement over traditional brazing. The effect of filler content on joint strength, oxidation resistance, and thermal shock resistance has been systematically investigated. The results show that increasing the filler content from 0 to 50 wt% increases shear strength up to a maximum of 25.97 MPa at 15 wt% SiC and 15 wt% graphite powder. The oxidation and thermal shock tests reveal that the joints exhibit a decrease in shear strength due to oxidation at temperatures above 600 °C, with a significant reduction occurring between 600 °C and 700 °C. After seven thermal shock cycles at 800 °C, the shear strength of the joints remains relatively high, indicating the good thermal shock resistance of the bonding layer. The method proposed in this study provides a new approach for controlling residual silicon and enhancing the properties of C/C-SiC joints.
研究领域:
材料科学
·
复合材料
·
连接技术
·
热分析
·
陶瓷基复合材料
✓ 已验证
产品关联
DOI
高影响因子
COMPOSITES PART B-ENGINEERING
·
2024
·
IF 12.7
Junjie Xu,Wei Sun,Xiang Xiong,Hongbo Zhang
Compared with the traditional C/C composites modified by ultra-high-temperature ceramics (C/C-UHTCs), those modified by metal/medium-entropy ceramics have excellent mechanical properties, thermophysical properties, and long-term ablation resistance. These composites have great potential towards improving the high-temperature resistance and service life of thermal protection systems for spacecraft. In this study, a new type of (Hf 0.5 Zr 0.3 Ti 0.2 )C–W–Cu cermet-modified C/C composites (C/C-(Hf 0.5 Zr 0.3 Ti 0.2 )C–W–Cu) was prepared at 1500 °C. Compared with C/C-UHTCs, the bending strength and fracture toughness of C/C-(Hf 0.5 Zr 0.3 Ti 0.2 )C–W–Cu increased by 70 % and 110 % to 364.25 MPa and 14.64 MPa m 1/2 , respectively. Due to the high thermal conductivity of Cu and W, the thermal conductivity of this new composite was 106 % higher than that of C/C-(Hf 0.5 Zr 0.3 Ti 0.2 )C (44.26 versus 21.53 W/m·K). Under a high heat flow of 4.18 MW/m 2 , this material exhibited very low mass and linear ablation rates (−0.163 mg/s and −0.193 μm/s, respectively). Active and passive protection occur during ablation due to the evaporative cooling of Cu, CuO, and WO 3 as well as a dense outer oxide layer that inhibits oxygen diffusion. The internal oxide layer forms a Hf-Zr-Ti-C-O framework mingled with Ti-rich Ti-Hf-Zr-C-O and an unoxidised W–Cu structure, effectively reducing the osmotic oxygen content. This work provides a new direction for developing thermal protection materials capable of long-term service in ultra-high-temperature environments.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR STRUCTURE
·
2023
·
IF 3.8
Peng Xiong,Tong-Wei Zhang,Shi-Ming Li,Mei-Yu Xu,Guang-Ming -Liang,Liu-Cheng Gui,Xiu-Jian Wang
Two tetranuclear copper cages with tubular type, [Cu 4 (BMBA) 4 ((CH 3 ) 2 N) 2 (H 2 O) 2 ] ( 1 ) and [Cu 4 (BMBA) 4 (Bipy)(H 2 O) 2 ] ( 2 ), were successfully constructed by the reaction of Cu(NO 3 ) 2 with dicarboxylic acid 4,4′-[( ethylazanediyl ) bis ( methylene )]-bis[(1,1′-biphenyl)-2-carboxylic acid] (H 2 BMBA) under solvothermal conditions. The complexes 1 and 2 exhibit a similar cage structure, formed by four ligands connecting two binuclear copper paddle-wheel secondary building units (SBUs). Interestingly, the complex 2 was obtained by appropriately binding of 4, 4′-bipyridine (Bipy) molecule on the axial positions of two Cu paddle-wheels inside the cage. For this reason, the complex 2 exhibits excellent stability in some common organic solvents at room temperature and aqueous solutions with a pH of 2 to 12. Upon thermal activation of complex 2 , the coordinated water molecules can be removed, and its exposed metal active-sites show Lewis acid character, which can be used an efficient heterogeneous catalysis of Knoevenagel condensation (C C) and Clauson-Kaas (C N) reactions.
研究领域:
化学
·
材料科学
·
催化反应
✓ 已验证
DOI
高影响因子
ADVANCED MATERIALS
·
2023
·
IF 29.4
Wenzheng Zhang,Mingyi Tan,Daming Chen,Boqian Sun,Yuan Cheng,Liancai Xun,Jingsheng Hu,Chenlin Hou,Yuxuan Liu,Yuhao Fang,Ping Hu,Wenbo Han,Shun Dong,Shanyi Du,Jiecai Han,Shuxi Miao,Qidong Yang,Yanchun Zhou,Xinghong Zhang
Sugars are renewable resources essential to human life, but they are rarely used as raw materials for the industrial production of carbon-based materials, especially for the preparation of carbon fiber-reinforced carbon-matrix (C/C) composites, which are extremely useful for the semiconductor and aerospace sectors. Herein, a method utilizing sugar-derived carbon to replace petrochemicals as dense matrix to preparing C/C composites is reported. The matrix from sugar-derived C/C (S–C/C) composites has a nanocrystalline graphite structure that is highly thermally stable and effectively bonded to the carbon fibers. The mechanical properties of the S–C/C composite are comparable to those prepared from petrochemical sources; significantly, it exhibits a linear ablation rate of 0.03 mm s −1 after 200 s of ablation at 3000 °C in 10 MW m −2 heat flux. This new class of S–C/C is promising for use in a broad range of fields, ranging from semiconductor to aerospace.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Small
·
2023
·Vol. 20
·期 3
·2304990
·
IF 13.3
Na Ye,Wenchao Sheng,Riguang Zhang,Binhang Yan,Zhao Jiang,Tao Fang
The splitting of the C–C bonds of ethanol remains a key issue to be addressed, despite tremendous efforts made over the past several decades. This study highlights the enhancement mechanism of inexpensive NbN-modified Pd 1 Sn 3 -NbN/C towards the C–C bonds cleavage for alkaline ethanol oxidation reaction (EOR). The optimal Pd 1 Sn 3 -NbN/C delivers a catalytic activity up to 43.5 times higher than that of commercial Pd/C and high carbonate selectivity (20.5%) toward alkaline EOR. Most impressively, the Pd 1 Sn 3 -NbN/C presents good durability even after 25 200 s of chronoamperometric testing. The enhanced catalytic performance is mainly due to the interfacial interaction between PdSn and NbN, demonstrated by multiple structural characterization results. In addition, in situ ATR-SEIRAS (Attenuated total reflection-surface enhanced infrared absorption spectroscopy) results suggest that NbN facilitates the C–C bonds cleavage towards the alkaline EOR, followed by the enhanced OH adsorption to promote the subsequent oxidation of C1 intermediates after doping Sn. DFT (density functional theory) calculations indicate that the activation barriers of the C–H bond cleavage in CH 3 CH 2 OH, CH 3 CHOH, CH 3 CHO, CH 3 CO, CH 2 CO, and the C–C bond cleavage in CH 3 CO, CH 2 CO, CHCO are evidently reduced and the removal of adsorbed CH 3 CO and CO becomes easier on the PdSn-NbN/C catalyst surface.
研究领域:
材料科学
·
电化学
·
表面科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2024
·
IF 3.8
Chuhan Zhang,Yanchang Chu,Linying Fu,Qiuyue Wang,Rui Ma,Donghai Xu,Le Yang
Lignin, a renewable resource rich in aromatic ring structures in nature, is an ideal natural source to produce aromatic compounds and cycloparaffin. Herein, we prepare MOF-derived Ni–MoxC/C and Co–MoxC/C as catalysts for the depolymerization of lignin and dimeric model compounds. Diphenyl ether (DPE) with 4-O-5 bond, benzyl phenyl ether (BPE) with α-O-4, and phenethyl phenyl ether (PPE) with β-O-4 are chosen as dimeric model compounds. Overall, Ni–MoxC/C and Co–MoxC/C show distinguished different activity toward product distribution. Ni–MoxC/C facilitates both C–O bond cleavage and hydrogenation of the benzene ring, and the main products are ethyl cyclohexane and cyclohexanol for all three model compounds. In contrast, Co–MoxC/C only facilitates C–O bond cleavage and obtains phenol and ethylbenzene as products. Similarly, for the depolymerization of lignin, cycloparaffins are obtained on Ni–MoxC/C, while phenol, guaiacol, 2,6-dimethoxyphenol, and their respective derivatives are obtained on Co–MoxC/C.
研究领域:
化学工程
·
可再生资源利用
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2014
·
IF 3.309
Junjie Zhang,Fang Lu,Weiqiang Yu,Jiazhi Chen,Shuai Chen,Jin Gao,Jie Xu
The use of high pressure fossil derived hydrogen limits the commercial prospects of transforming sorbitol to glycols. Ni–Re/C catalyst which was developed in this study demonstrated high selectivity toward hydrogenative cleavage of C2–C3 and C3–C4 bonds of sorbitol to produce glycols under 1 MPa nitrogen. Acetol which is proposed as important intermediate to explain the reaction mechanism was first detected in the sorbitol conversion reactions. Detailed investigations showed that the presence of Re could prevent the sintering of Ni particles during the reduction process and make the catalyst efficiently generate hydrogen on the active sites to selectively cleave C–C bonds in sorbitol under nitrogen atmosphere.
研究领域:
催化化学
·
绿色化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2025
·
IF 6.2
Yuanming Zhou,Shuxin Li,Shuangxing Zhu,Ruizhi Liu,Zhenxiao Tang,Maozhong Yi,Ke Peng
To investigate the influence of (Ta,Zr)C on the ablation resistance of C/C composites, C/C-(Ta 0.5 Zr 0.5 )C-SiC, C/C-(Ta 0.33 Zr 0.67 )C-SiC, and C/C-(Ta 0.2 Zr 0.8 )C-SiC were prepared with different Zr/Ta ratios through high-solid-loading slurry impregnation combined with precursor infiltration and pyrolysis. The flexural performance and ablation resistance both improved with an increasing Zr/Ta ratio. Compared to C/C-(Ta 0.5 Zr 0.5 )C-SiC and C/C-(Ta 0.33 Zr 0.67 )C-SiC, the flexural strength of C/C-(Ta 0.2 Zr 0.8 )C-SiC increased by 74.17 % and 24.29 %, respectively. The mass ablation rate was reduced by 74.33 % and 81.02 %, while the linear ablation rate was reduced by 98.60 % and 97.65 % after 120 s of ablation, respectively. The variations in Zr/Ta ratios affected the formation, integrity, and performance of the microstructure, which was composed of a Zr-rich oxide skeleton combined with Ta-rich oxide binder within the Ta-Zr-O oxide layer on the composite surface, ultimately enhancing the overall ablation resistance of these composites.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Catalysis
·
2022
·
IF 13.7
Xuliang Lin,Xing Fei,Dalang Chen,Yi Qi,Quanzhou Xu,Yinchun Liu,Qian Zhang,Sha Li,Tiejun Wang,Yanlin Qin,Xueqing Qiu
The conversion of renewable bioethanol into high-energy-density higher alcohols has become essential for meeting the increasing global demand to achieve carbon neutrality. In this study, Zn- and nitrogen-codoped Ni-based lignin-derived carbon catalysts (NiZn@NC) were prepared by solvent volatile self-assembly and in situ reductive carbonization using pulp and paper waste stream alkali lignin as the carbon source. Lignin amphipathic derivatives with −COOH and −NH2 groups would coordinate with metal ions to form a stable lignin–metal framework; thus, the lignin-derived carbon layer disperses the NiZn bimetallic catalyst and prevents from corroding. At an amination reagent/lignin mass ratio of 1:2, an ethanol conversion of 75.2% and a high alcohol yield of 41.7% were achieved over the Ni20Zn1@NC catalyst. Experimental results and density functional theory calculations showed that Zn doping improved the electronic environment and defect structures of metallic Ni and carbon carrier, which effectively inhibited C–C cleavage and suppressed the byproduct formation, such as methane. Thereby, the synergetic effect between Ni and Zn facilitated the efficient conversion of aqueous ethanol into higher alcohols by the Guerbet reaction. This work provides a strategy of in situ pyrolytic doping and stabilizing of renewable biomass macromolecules as the frameworks for the construction of highly active and cost-efficient catalysts for ethanol upgrading.
研究领域:
催化化学
·
可再生资源利用
·
材料科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2025
·
IF 13.2
Yun Tang,Jingqi Ruan,Yalou Xin,Xiaohu Ren,Hudie Yuan,Xianhu Liu,Qiang Chen
The development of metal–organic frameworks (MOFs)-derived magnetic carbon-based materials for high-efficiency electromagnetic wave (EMW) absorption has attracted widespread attention. While these MOFs-derived composites have shown exceptional performance in absorbing EMWs within the X and Ku bands, the pursuit of effective absorption at lower frequencies remains a challenge. Herein, we demonstrate a novel strategy to synthesize hollow Co@C/C rods with excellent C-band EMW absorption via acetic acid etching and pyrolysis of core–shell ZIF-8@ZIF-67. Based on acetic acid etching, ligand-deficient ZIF-8@ZIF-67 rods with abundant mesoporous structures are constructed, enabling precise control over the Co nanoparticles content, graphitization degree, and pyridinic N doping in the derived Co@C/C. This simple fine-tuning approach simultaneously reduces dipole polarization by lowering the pyridinic N doping concentration, suppresses interfacial polarization and conduction loss through reducing the number of graphitic carbon layer, and enhances magnetic loss by increasing the Co content. These combined effects collectively improve the impedance matching of Co@C/C for low-frequency absorption. Notably, as the volume of acetic acid solution increases, the absorption frequency band of Co@C/C gradually shifts from the Ku-band to the C-band, while sustaining superior EMW absorption performance. At the filling ratio of merely 11 %, the RL min values for Co@C/C-20 and Co@C/C-30 achieve −49.8 dB and −34.7 dB at 7.2 GHz and 6.8 GHz, respectively. This study offers a valuable approach to the development of lightweight materials with excellent EMW absorption in C-band.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2023
·
IF 7.3
Jin Yuan,Zhiwei He,Hongbo Zhang
Selective C–H bond oxidation of cyclohexane into KA oil (ketone-alcohol) is of vital importance in both fundamental research and industrial applications while limited by complex reaction network and suffering from low efficiency. In this study, Ce(OH)SO 4 · x H 2 O was chosen as a probe to systematically investigate the C–H bond activation and C–C bond rupture as a function of various reaction parameters, including the reactant/product concentrations, catalyst applied, reaction temperatures, acidic concentrations etc, and found that bi-molecule of C 6 H 12 was probably involved in both C–H bond rupture and C–C bond cleavage and both were controlled by one deprotonation elementary step with ·O 2 – and h + as the key active components, which were supported by parity fittings and primary KIEs determined. In addition, the C–C bond rupture was found to be mainly following C 6 H 10 O to ε-caprolactone and further to linear acids reaction path. Hopefully, this study could help people find/optimize reaction systems in selective hydrocarbon upgradings.
研究领域:
化学工程
·
有机化学
·
催化
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）