MATERIALS & DESIGN
·
2018
·
IF 4.525
Haibo Ouyang,Guibiao Li,Cuiyan Li,Jianfeng Huang,Jie Fei,Jing Lu
C/C-Zr-Si-O composites were prepared by carbothermal reduction of hydrothermal co-deposited ZrO 2 , SiO 2 , and C. The bulk density of composites reached 1.71 g/cm 3 with 8 cycles of co-deposition. The matrix of the composites includes ZrC, SiC, ZrO 2 , and SiO 2 with fine grain size (300–500 nm) and homogeneous distribution. The mass and linear ablation rate of C/C-Zr-Si-O composites were 0.112 mg/cm 2 ·s and 0.46 μm/s, respectively, under a plasma flame for 120 s. The attractive ablation resistance of the composites resulted from its unique structure, which tends to form a continuous ZrO 2 -SiO 2 glass layer in the ablation center, a layer of SiO 2 -ZrO 2 bubbles in the transition region, and fluffy SiO 2 nanowires layer in the heat-affected region. These ablation layers were barriers to restrain the diffusion of oxidative gas and heat. The C/C-Zr-Si-O composites provide an alternative ceramics system with attractive ablation resistance, while carbothermal reduction of hydrothermal co-deposited oxides is a feasible method for the structural design of carbon fiber reinforced ultra-high temperature ceramic.
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RSC Advances
·
2015
·Vol. 5
·期 117
·96372-96376
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IF 3.84
Zheng-Jun Wang,Peng-Hui Wang,Jing-Jing Lv,Jiu-Ju Feng,Xinhua Xu,Ai-Jun Wang,Chak-Tong Au,Renhua Qiu
Commercial copolymer Luviset clear (L1), an environmentally benign and efficient ligand, was used to facilitate the catalytic performance of Cu(NO3)2 for homo-coupling of terminal alkynes. A series of substituted aromatic and aliphatic terminal alkynes were investigated. It was found that Cu(NO3)2@L1 can catalyze the C–C coupling reactions without any other base, and the corresponding diynes are generated in good to excellent yield. X-ray photoelectron spectroscopy was used to study the reaction mechanism, and the results evidence a Cu(II)/Cu(I) catalytic system. Additionally, the catalyst can be easily separated and reused without showing significant loss of catalytic activity.
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CORROSION SCIENCE
·
2015
·
IF 4.422
Dong Huang,Mingyu Zhang,Qizhong Huang,Liping Wang,Liang Xue,Xian Tang,Kejian He
C/C–ZrB 2 –ZrC–SiC composites were fabricated by polymer infiltration and pyrolysis (PIP) with a preform of C f /ZrB 2 . The ZrB 2 powders were sprayed onto fabric layer by layer before the fabric is needled. After introduction of resin carbon and ZrC–SiC into the preform, a ceramic coating on the matrix and fibres was formed in the composites. The plasma ablation test indicates that the composites possess a good ablation resistance after ablation for 180 s and 240 s. The SiO 2 –ZrO 2 barrier layer, high temperature Zr–Si–O glass layer and heat dissipation all contribute to the good ablation resistance of the composites.
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ADVANCED FUNCTIONAL MATERIALS
·
2024
·Vol. 34
·期 44
·2405922
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IF 18.5
Minmin Ma,Ran Wang,Li Shi,Ronghua Li,Jie Huang,Zhuo Li,Peng Li,Elena Yu. Konysheva,Yanbo Li,Gang Liu,Xiaoxiang Xu
Photocatalytic carbon-carbon (C─C) coupling of benzyl alcohol is a promising means to coproduce the value-added chemicals with H 2 but is generally subject to low efficiency in terms of photon utilization. Here, efficient benzyl alcohol C─C coupling is achieved over Zn 2 In 2 S 5 containing a tunable content of Zn vacancies ( V Zn ). The V Zn tends to form shallow defect states below the conduction band that can expedite photocarrier separation by collecting the photo-generated electrons. The V Zn -collected electrons are essential for a high selectivity of the C─C coupling reactions because they enable a fast elimination of the byproduct benzaldehyde by catalyzing its reduction back to the ketyl radicals. Under simulated sunlight, the V Zn -containing Zn 2 In 2 S 5 accomplishes ≈100% conversion of benzyl alcohol for merely 1 h and attains ≈100% selectivity for the C─C coupling compounds for 2 h, delivering an apparent quantum yield as high as 7.7% at 420 ± 20 nm. The benefits of V Zn have also been verified by the theoretical calculations that indicate reduced energy barriers for various surface reactions in the presence of V Zn . This work brings fresh mechanistic insights into the role of V Zn and can serve as a useful guideline in the design of efficient photocatalysts.
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Nature Communications
·
2024
·Vol. 15
·期 1
·1-12
·
IF 14.7
Wang Shifu,Li Fuhua,Zhao Jian,Zeng Yaqiong,Li Yifan,Lin Zih-Yi,Lee Tsung-Ju,Liu Shuhui,Ren Xinyi,Wang Weijue,Chen Yusen,Hung Sung-Fu,Lu Ying-Rui,Cui Yi,Yang Xiaofeng,Li Xuning,Huang Yanqiang,Liu Bin
Manipulation C-C coupling pathway is of great importance for selective CO 2 electroreduction but remain challenging. Herein, two model Cu-based catalysts, by modifying Cu nanowires with Ag nanoparticles (AgCu NW) and Ag single atoms (Ag 1 Cu NW), respectively, are rationally designed for exploring the C-C coupling mechanisms in electrochemical CO 2 reduction reaction (CO 2 RR). Compared to AgCu NW, the Ag 1 Cu NW exhibits a more than 10-fold increase of C 2 selectivity in CO 2 reduction to ethanol, with ethanol-to-ethylene ratio increased from 0.41 over AgCu NW to 4.26 over Ag 1 Cu NW. Via a variety of o perando /in-situ techniques and theoretical calculation, the enhanced ethanol selectivity over Ag 1 Cu NW is attributed to the promoted H 2 O dissociation over the atomically dispersed Ag sites, which effectively accelerated *CO hydrogenation to form *CHO intermediate and facilitated asymmetric *CO-*CHO coupling over paired Cu atoms adjacent to single Ag atoms. Results of this work provide deep insight into the C-C coupling pathways towards target C 2+ product and shed light on the rational design of efficient CO 2 RR catalysts with paired active sites.
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PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2024
·
IF 20.2
Fu Li,Jingnan Yang,Xiaomei Zhou,Fei Han,Qian Huo,Qingxin Guan,Wei Li
Converting CO 2 to ethanol through photothermal catalysis faces significant challenges due to it involves multi-electron reduction and kinetically sluggish C-C coupling process. Here, copper and a minor quantity of palladium are encapsulated within the cage of UiO-66 using a dual-solvent-sonication method to form ultrafine Cu 2 O/Cu-Pd clusters. The Cu-Cu 2 O serves as an electron center to enhance CO 2 uptake and activation, while the incorporation of Pd accelerates H 2 activation. Due to differences in electronegativity , electrons tend to transfer from Cu to Pd, which reduces the electrostatic repulsion between intermediates and facilitates the coupling of *CO and *CHO. The photothermal ethanol yield of Cu 6 Pd@UiO-66 reached 1077.69 μmol·g cat –1 ·mL –1 with a selectivity of 94.62%, representing an 11.64-fold increase over the non-illumination, and a 3.11-fold enhancement compared with Cu 6 @UiO-66. This study offers evidence supporting the promotion of C-C coupling through an asymmetric electron distribution , potentially advancing the conversion of CO 2 to liquid products.
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ACS Sustainable Chemistry & Engineering
·
2025
·
IF 7.3
Zhouxuan Zang,Jianhua Zhou,Ningke Pang,Wencai Bai,Yong Xiang,Yi Yu,Li Xu,Guoji Liu
High-energy-density sustainable aviation fuels are recognized as effective means to mitigate carbon emissions in the aviation sector. Here, we report various metal-modified layered double hydroxides (LDHs). The screened MgAlSn-LDH catalyst incorporating abundant oxygen vacancies and strong base sites yields (E)-1-(furan-2-yl)-5-methylhex-1-en-3-one (ALD) over 96% at 120 °C for 4 h. The catalyst exhibits promising long-term stability in a fixed-bed reactor at 170 °C. A combination of investigations using in situ DRIFTS studies and DFT calculations reveals that MgAlSn-LDH enhances the adsorption of methyl isobutyl ketone (MIBK) and furfural (FF). Further calculations have shown that the synergy of oxygen vacancies and strong base sites decreases the energy barrier of MIBK enolation, which increases the rate of the enolation reaction. This research provides a versatile synthesis method for improving the alkaline catalytic activity of LDH catalysts, and the performance of the catalysts can be extended to other upgrading processes of biomass chemicals.
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Journal of Environmental Sciences
·
2025
·
IF 6.3
Canyan Yang,Wei Liu,Zhao Zuo,Jinhua Xiao,Huawang Zhao,Bihong Lv,Zuoming Zhou,Xiaomin Wu,Guohua Jing
Carbon-carbon (C-C) coupling, the rate-determining step in electrocatalytic CO 2 reduction reaction (CO 2 RR) to C 2+ products, has low efficiency and poor stability. It originates from an ineffective water dissociation capability and a high energy barrier for the C-C coupling pathway on existing catalysts. Herein, an efficient and facile Br-CuO electrocatalyst was synthesized to promote water dissociation and achieve an impressive Faradic Efficiency (FE) of around 60% C 2 H 4 at a current density of up to -350 mA/cm 2 with stability of 16 h. Combinative theoretical and experimental protocols strongly evidence that the architecture of Cu 0 -Cu + sites is crucial for the enhancement in CO 2 RR activity. Cu 0 activates CO 2 and Cu + strengthens *CO adsorption to further boost C-C coupling. Furthermore, Br doping can facilitate the dissociation of water to generate *H, which promotes the protonation of *CO to *CHO, thereby enabling the low energy barrier asymmetric *CHO-*CO coupling. The in situ ATR-FTIR and Density functional theory (DFT) was analyzed to explain the reaction mechanism and pathway. This study elucidates the critical function of water dissociation and provides a promising avenue to efficient CO 2 -to-C 2 H 4 electrocatalysis.
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Frontiers of Chemical Science and Engineering
·
2023
·Vol. 17
·期 6
·772-783
·
IF 4.5
Gao Xiu,Luo Beining,Hong Yanping,He Peihang,Zhang Zedong,Wu Guoqiang
Development of a titanium silicalite-1 (TS-1) catalyst with good crystallinity and a four-coordinate Ti framework is critical for efficient catalytic oxidation reaction under mild conditions. Herein, a size-controlled TS-1 zeolite (TS-1#0.1ACh (acetylcholine)) was synthesized via steam-assisted crystallization by introducing acetylcholine as a crystal growth modifier in the preparation process, and TS-1#0.1ACh was also employed in epoxidations of different substrates containing C=C double bonds. The crystalline sizes of the as-synthesized TS-1#0.1ACh catalysts were controlled with the acetylcholine content, and characterization results showed that the particle sizes of highly crystalline TS-1#0.1ACh zeolite reached 3.0 µm with a good Ti framework. Throughout the synthetic process, the growth rate of the crystals was accelerated by electrostatic interactions between the connected hydroxyl groups of the acetylcholine modifier and the negatively charged skeleton of the pre-zeolites. Furthermore, the TS-1#0.1ACh catalyst demonstrated maximum catalytic activity, good selectivity and high stability during epoxidation of allyl chloride. Importantly, the TS-1#0.1ACh catalyst was also highly versatile and effective with different unsaturated substrates. These findings may provide novel, easily separable and large TS-1 catalysts for efficient and clean industrial epoxidations of C=C double bonds.
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高影响因子
Journal of Physical Chemistry C
·
2025
·
IF 3.2
Xiang Chen,Shaohua Chen,Pengxin Liu,Chaodan Pu
We report the efficient C–C coupling between benzyl alcohol and benzaldehyde to hydrobenzoin using CdSe/CdS quantum dots as visible-light photocatalysts and sodium oxide as a cocatalyst. The optimized conditions resulted in a reaction with a selectivity of hydrobenzoin >95%, an apparent quantum yield of 23.6% under the excitation by 520 nm LED, and a turnover frequency of 56.8 mmol g–1 h–1. Reactant concentration-dependent experiments demonstrated that benzaldehyde can process fast proton-coupled electron transfer, improving the utilization of photogenerated electrons. Photoluminescence quenching experiments and reactions with deuterated benzaldehyde confirmed that due to the in situ produced hydrogen ions, the hydroxymethyl radicals would process efficient reverse conversion from hydroxymethyl radicals to benzyl alcohol, resulting in noneffective charge transfer. Formation of sodium benzyloxide can eliminate the in situ produced hydrogen ions around the hydroxymethyl radical, suppressing this reverse conversion and improving the utilization efficiency of transferred holes and electrons.
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Science Advances
·
2022
·Vol. 8
·期 40
·
IF 14.957
Jingzhong Qin,Bo Han,Xixi Liu,Wen Dai,Yanxin Wang,Huihui Luo,Xiaomei Lu,Jiabao Nie,Chensheng Xian,Zehui Zhang
The cleavage and functionalization of recalcitrant carbon─carbon bonds is highly challenging but represents a very powerful tool for value-added transformation of feedstock chemicals. Here, an enzyme-mimic iron single-atom catalyst (SAC) bearing iron (III) nitride (FeN 3 ) motifs was prepared and found to be robust for cleavage and cyanation of carbon–carbon bonds in secondary alcohols and ketones. High nitrile yields are obtained with a wide variety of functional groups. The prepared FeN 3 -SAC exhibits high enzyme-like activity and is capable of generating a dioxygen-to-superoxide radical at room temperature, while the commonly reported FeN 4 -SAC bearing FeN 4 motifs was inactive. Density functional theory (DFT) calculation reveals that the activation energy of dioxygen activation and the activation energy of the rate-determining step of nitrile formation are lower over FeN 3 -SAC than FeN 4 -SAC. In addition, DFT calculation also explains the catalyst’s high selectivity for nitriles.
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高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Cuiyan Li,Jintao Wang,Haibo Ouyang,Tianzhan Shen,Zihao Chen,Leer Bao,Yanlei Li,Qiaoqiao Wang
s To reduce the cost of C/C-ZrC-SiC composites, an inorganic salt strategy was proposed for fabricating these composites using the PIP method. The precursor solution, composed of zirconium tetrachloride, tetraethoxysilane, and furfuryl alcohol, exhibits lower viscosity, facilitating more efficient infiltration into the C/C matrix and reducing porosity in the final composite. Fine ZrC and SiC particles, with an average particle size of 2.03 μm, were homogeneously distributed within the composite matrix. The resulting material demonstrated a flexural strength of 193.2 MPa, along with linear and mass ablation rate of 0.03 μm/s and 0.10 mg/s, respectively. The uniform distribution of fine ZrC and SiC particles within the dense matrix significantly enhances mechanical properties and ablation resistance. During ablation, these particles promote the formation of a protective oxide scale consisting of a dense outer ZrO 2 layer and an inner SiO 2 layer. The dense ZrO 2 layer effectively retards oxygen diffusion into the composite, providing excellent resistance to mechanical erosion, while the continuous SiO 2 layer minimizes the ingress of oxidizing gases, further enhancing ablation resistance. This study demonstrates that the inorganic salt strategy can be used to fabricate C/C-ZrC-SiC composites at a lower cost while achieving superior properties, offering a promising approach for producing C/C-UHTCs composites.
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