APPLIED CATALYSIS B-ENVIRONMENTAL
·
2025
·
IF 21.1
Xiuzheng Deng,Jiangchuan Liu,Jun Cai,Dan Wang,Huihui Mao,Changhai Liu,Zhongyu Li,Zhenhui Kang,Qian Liang
High production capacity of C 2 products from CO 2 photoreduction remains a significant challenge owing to the difficulty of C-C coupling and weak hydrogenation. Herein, a novel stepwise C-C coupling and hydrogenation mechanism is developed on multisite catalyst to enhance the performance of photocatalytic CO 2 reduction to C 2 products. The active Co cluster, carbon dots (CDs) and Cs 3 Bi 2 Br 9 quantum dots (QDs) are reinforced with robust carbon matrix, which allows to accelerate mass/electron transport and improve stability of catalytic sites, enabling a competitive C 2 H 4 evolution rate of 57.60 μmol g cat −1 h −1 with 67.70 % C 2 H 4 selectivity. In situ experiments coupled with theoretical calculations verify that Co and CDs capture photogenerated electrons from Cs 3 Bi 2 Br 9 to form key intermediate Co-*CO-*CO-CDs. After *CO-*CO coupling on Co site, the proximal CDs provide plenty of protons to conduct continuous hydrogenation toward coupling site until C 2 H 4 is formed. This study paves a novel pathway to regulate C-C coupling and hydrogenation for CO 2 conversion to C 2 hydrocarbons.
研究领域:
催化化学
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环境科学
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材料科学
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物理化学
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能源化学
·
纳米科技
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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
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航空航天工程
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产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Junjie Xu,Wei Sun,Xiang Xiong,Hongbo Zhang,Lingkun Yang
Spacecraft thermal protection materials need to survive long-term exposure to oxygen-containing environments at 2400 °C. In this study, a high-density and low-porosity metal-ceramic-modified composite was prepared at a low temperature (1500 °C) in the presence of W and Cu using combined slurry brushing and reactive melt infiltration methods. An investigation of the composite formation mechanism and the effects of W and Cu indicated that W and ZrB 2 were formed via dissolution-precipitation and the external diffusion of C and B, respectively. The low reaction temperature and the metallic phases significantly improved the mechanical properties, thermophysical properties, and long-term ablation behaviours of C/C–ZrC–ZrB 2 –W–Cu. Compared to traditional C/C–ZrC, the flexural strength and fracture toughness of the composite increased by 71.56 % and 90.05 % to 345.95 MPa and 14.52 MPa m 1/2 , respectively, and the thermal conductivity increased by 174.93 % to 59.11 W/m·K. In addition, W and Cu effectively lowered the surface temperature by nearly 250 °C during 300 s ablation, and the mass and line ablation rates decreased to −0.272 mg/s and −0.247 μm/s, respectively.
研究领域:
材料科学
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航天工程
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产品关联
DOI
高影响因子
NANOTECHNOLOGY
·
2024
·Vol. 35
·期 49
·495704
·
IF 2.9
Gang Xiao,Zishuai Wang,Yu Jin,Fengping Wang
The selective cleavage of lignin C–C bonds is a highly sought-after process with the goal of obtaining low-molecular-weight aromatic chemicals from renewable resources. However, it remains a challenging task to achieve under mild conditions. Photocatalysis is a potentially promising approach to address this issue, but the development of efficient photocatalysts is still in progress. In this study, we introduce the heterostructured TiO2@g-C3N4 photocatalyst for the development of a visible light photocatalytic procedure for the selective cleavage of lignin C–C bonds under mild conditions. The photocatalyst displays favourable visible light absorption, efficient charge separation efficiency, and promising reusability. A typical β–O–4 dimer model, 2-phenoxy-1-phenylethanol, was effectively (96.0% conversion) and selectively (95.0 selectivity) cleaved under visible light at ambient conditions. This photocatalytic procedure was also effective when subjected to solar irradiation or other lignin dimer models with β–O–4 or β-1 linkages. This reaction occurred through a Cβ-centred radical intermediate and a six-membered transition state with photogenerated holes as the primary active species. The Cα–OH oxidative dehydrogenation of the substrate could also take place but was a relatively minor route. This study provides a new photocatalytic procedure for visible-light-driven lignin valorisation and sheds light on the design of high-performance nanocomposite photocatalysts for C–C bond cleavage.
研究领域:
化学工程
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材料科学
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可再生能源
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产品关联
DOI
PubMed
高影响因子
Nature Communications
·
2024
·Vol. 15
·期 1
·1-11
·
IF 14.7
Yang Xiaoju,Rong Chao,Zhang Li,Ye Zhenkun,Wei Zhiming,Huang Chengdi,Zhang Qiao,Yuan Qing,Zhai Yueming,Xuan Fu-Zhen,Xu Bingjun,Zhang Bowei,Yang Xuan
Developing in situ/operando spectroscopic techniques with high sensitivity and reproducibility is of great importance for mechanistic investigations of surface-mediated electrochemical reactions. Herein, we report the fabrication of highly ordered rhombic gold nanocube superlattices (GNSs) as substrates for surface-enhanced infrared absorption spectroscopy (SEIRAS) with significantly enhanced SEIRA effect, which can be controlled by manipulating the randomness of GNSs. Finite difference time domain simulations reveal that the electromagnetic effect accounts for the significantly improved spectroscopic vibrations on the GNSs. In situ SEIRAS results show that the vibrations of CO on the Cu 2 O surfaces have been enhanced by 2.4 ± 0.5 and 18.0 ± 1.3 times using GNSs as substrates compared to those on traditional chemically deposited gold films in acidic and neutral electrolytes, respectively. Combined with isotopic labeling experiments, the reaction mechanisms for C-C coupling of CO electroreduction on Cu-based catalysts are revealed using the GNSs substrates.
研究领域:
电化学
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表面科学
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材料科学
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光谱学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
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.
研究领域:
材料科学
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催化化学
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环境科学
✓ 已验证
产品关联
DOI
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.
研究领域:
材料科学
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航空航天工程
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Pei-dong Wu,Lanyun Li,Hu Li,Zhen Fang
Sustainable upgrading of biomass to high-value chemicals is greatly dependent on catalytic C-C/C-O bond cleavage of high selectivity. Here, an oxidation-enhanced photoelectrochemical protocol was developed to be capable of breaking different types of C-C bonds for efficiently producing aromatic carboxylic acids (85.0–99.8% yields) from lignin. Ni local electronic state of the prepared F-Fe 2 O 3 -Co:NiO x H y with excellent durability could be modulated, and high-valence Ni(Ⅳ) reactive species played a key role in the oxidative C-C bond scission of various lignin models. In-situ characterization and control experiments indicated that photocatalytic radical and electrocatalytic interface facilitated C-H/O-H delocalization, contributing significantly to the enhanced oxidation process. In addition, quantum calculations elaborated that photo-excited holes and Ni(Ⅳ) are key reactive species for enhancive electrocatalytic cleavage of different C-C bonds in lignin to exclusively furnish aromatic carboxylic acids. This research provides a renewable funnel strategy for using solar energy to produce high-value mono-functional products from biomass.
研究领域:
化学
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可再生能源
·
催化科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2024
·Vol. 14
·期 6
·1568-1578
·
IF 4.4
Qifeng Chen,Peng Zheng,Haodi Liu,Yuanrong Zhang,Shuaitao Li,Hongpian Guo,Yanfen Fang,Xun Hu,Ran Duan
The combination of photocatalytic dehalogenation of halogenated aromatics and C–C coupling synthesis of valuable organics is an interesting method for the elimination of pollutants and synthesis of valuable chemicals. Herein, we present a green method for the photocatalytic dehalogenation of benzyl bromide and selective coupling synthesis of bibenzyl achieved on the dual active sites of single-atom Cu and surface oxygen vacancies (VOS) generated in situ on ultrathin 2D-TiO2(B) nanosheets. The experimental results show that single-atom Cu sites on ultrathin TiO2(B) nanosheets can improve charge transfer and separation efficiency and stabilize VOS formed in situ; the presence of VOS not only improves light absorption capacity but also favors the adsorption of reactant benzyl bromide molecules. More importantly, the dual sites of single-atom Cu and adjacent VOS form a solid frustrated Lewis pair, favor the adsorption of benzyl bromide molecules, activate the C–Br bond, and boost the C–C coupling synthesis of bibenzyl. This work provides a novel insight into photocatalytic C–C coupling through the synergistic effect of single-atom Cu and VOS on ultrathin nanosheet photocatalysts.
研究领域:
材料科学
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环境科学
·
化学工程
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产品关联
DOI
高影响因子
RARE METALS
·
2025
·
IF 11
Dong Yu-Guo,Kong Wen-Jing,Ma Zhuang,Yang Yong,Wang Ping,Sheng Shi-Xiong,Dong Lin,Gu Xiao-Li,Chen Zu-Peng
The oxidation of lignin model compounds to esters via C–C bond cleavage has attracted considerable attention, as esters could be used as important polymer precursors and pharmaceutical intermediates. However, most studies focus on designing homogeneous or noble metal catalysts and conducting the reactions under basic conditions. Here, we report an efficient process for the C–C bond cleavage of lignin model compounds and selectively producing esters over different shaped CeO 2 (i.e., nanospheres (S), nanorods (R), nanoparticles (P), and nanocubes (C)) under base-free conditions. Specifically, the yield of methyl anisate from the aerobic oxidation of 1-(4-methoxyphenyl)ethanol reaches 77.6% over CeO 2 -S in one hour (91% in 9 h), exhibiting higher performance compared to other evaluated CeO 2 catalysts (6.4%–40.2%). Extensive characterizations and experimental investigations reveal that the density of weak base sites and oxygen vacancies on the CeO 2 surface is positively correlated with the yield of methyl esters. Furthermore, the reaction pathway is investigated, which confirms that 1-(4-methoxyphenyl)ethanol first undergoes two reactions (i.e., etherification and dehydrogenation) to produce intermediates of 1-methoxy-4-(1-methoxy-ethyl)-benzene and 1-(4-methoxyphenyl)ethanone, respectively, followed by a series of functional group transformations to generate the targeted methyl anisate ultimately. Graphical abstract
研究领域:
催化化学
·
材料科学
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产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2025
·
IF 6.3
Cuiyan Li,Siyi Qi,Haibo Ouyang,Tianzhan Shen,Zihao Chen,Yanlei Li,Jiaqi Liu
To develop active thermal protection for ultra-high temperature ceramics, C/C-ZrC-CuNi composites were fabricated using a PIP method. This study systematically studied the influence of CuNi alloy content on the microstructure, mechanical properties, thermal conductivity, and ablation resistance of the composites. The incorporation of CuNi alloy significantly enhanced the sintering of the ZrC-C matrix, resulting in improved densification of the composites. Furthermore, the presence of CuNi alloy promoted the graphitization of the carbon matrix, thereby enhancing the thermal conductivity. The composites with the highest CuNi alloy content (ZCN4 sample) exhibited the greatest density（2.26 g/cm 3 ） and thermal conductivity（32.3 W/m·k）, along with superior ablation resistance, with mass and line ablation rates of 2.09 mg/s and 2.06 μm/s. This enhanced ablation resistance can be primarily attributed to the sweating cooling effect of the CuNi alloy, which effectively reduces the ablation temperature. Additionally, the formation of Cu 2 O and NiO during ablation acts as sintering aids, facilitating the development of a compact ZrO 2 scale that resists flame erosion. The increased thermal conductivity of the composite further mitigates the temperature rise on the ablation surface.
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
Reaction Kinetics Mechanisms and Catalysis
·
2024
·Vol. 137
·期 4
·1911-1925
·
IF 1.7
Song Linyan,Nie Genkuo,Chen Xiulei,Wang Hongyu,Liu Shiwei,Yu Hailong,Liu Xuguang,Yang Guihua,Yu Shitao
The multifunctional groups of 5-hydroxymethylfurfural (5-HMF) make it could extend carbon chain by different C–C coupling reactions and extensively applied in the bio-jet fuel synthesis. Herein, one-pot reaction of lignocellulose derived chemicals with 5-HMF was studied by experimental and density functional theory (DFT) methods. The kinetic models of products were established and the apparent activation energies of the products by C–C coupling reaction of phenol, anisole, guaiacol, cyclohexanone and acetone with 5-HMF on Hβ were 95.3 kJ/mol, 104.8 kJ/mol, 90.4 kJ/mol, 90.0 kJ/mol and 112.2 kJ/mol, indicating these reactions centering on 5-HMF competitive intensively. Then the effects of the catalysis were analyzed by applying commercial catalysis to the mixed coupling reaction of 5-HMF. It was found that Brønsted acid is more favorable to alkylation reaction, and Lewis acid is more beneficial to aldol condensation reaction. By Fukui function, due to the nucleophilic index of cyclohexanone (2.74 eV) is higher than that (2.48 eV) of acetone, and the Mulliken electronegativity (3.43 eV) is weaker than that (3.55 eV) of acetone, cyclohexanone is more conducive than acetone to the aldol condensation reaction. This work provides data reference for product regulation in the bio-jet fuel synthesis.
研究领域:
化学工程
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可再生资源
·
能源科学
✓ 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）