共查询到20条相似文献,搜索用时 15 毫秒
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通过壳聚糖(chitosan)中的氨基与MPA-CdSe(MPA=3-巯基丙酸)量子点(QDs)表面Cd2+的配位作用, 构建了MPA-CdSe@chitosan组装体. 壳聚糖中丰富的氨基和疏水结构为量子点提供了富CO2及疏水的微环境, 从而提升了水相光催化CO2还原效率和选择性. 光催化实验结果表明, 在以抗坏血酸钠(NaHA)为电子牺牲体的条件下, MPA-CdSe@chitosan组装体在水中可将CO2光催化还原为CO, CO的生成效率和选择性分别比不含壳聚糖的MPA-CdSe QDs体系提升169倍和8.6倍. 用组装体系光催化60 h后, CO的生成效率为73.6 mmol/g(基于量子点质量), 对应的选择性达到51.0%, 具有良好的稳定性. 相似文献
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超临界二氧化碳制备聚合物微孔膜的研究进展 总被引:1,自引:0,他引:1
超临界二氧化碳做非溶剂制备聚合物微孔膜是一个新的研究热点,具有传质系数高、聚合物膜干燥速度快且不破坏结构、溶剂容易回收、CO2可循环使用、CO2的低毒性与环境友好性等特点.本文介绍采用超临界CO2制备聚合物微孔膜的热力学及动力学原理,重点介绍近年来采用此技术制备微孔膜的研究成果,如以聚苯乙烯(PS)、聚丙烯腈(PAN)、聚醚砜(PES)等为基体的微孔聚合物膜. 相似文献
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Lei Zou Zi-Ao Chen Duan-Hui Si Shuai-Long Yang Wen-Qiang Gao Kai Wang Prof. Yuan-Biao Huang Prof. Rong Cao 《Angewandte Chemie (International ed. in English)》2023,62(46):e202309820
Two-dimensional (2D) imine-based covalent organic frameworks (COFs) hold potential for photocatalytic CO2 reduction. However, high energy barrier of imine linkage impede the in-plane photoelectron transfer process, resulting in inadequate efficiency of CO2 photoreduction. Herein, we present a dimensionality induced local electronic modulation strategy through the construction of one-dimensional (1D) pyrene-based covalent organic frameworks (PyTTA-COF). The dual-chain-like edge architectures of 1D PyTTA-COF enable the stabilization of aromatic backbones, thus reducing energy loss during exciton dissociation and thermal relaxation, which provides energetic photoelectron to traverse the energy barrier of imine linkages. As a result, the 1D PyTTA-COF exhibits significantly enhanced CO2 photoreduction activity under visible-light irradiation when coordinated with metal cobalt ion, yielding a remarkable CO evolution of 1003 μmol g−1 over an 8-hour period, which surpasses that of the corresponding 2D counterpart by a factor of 59. These findings present a valuable approach to address in-plane charge transfer limitations in imine-based COFs. 相似文献
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Dr. Yajun He Yun Zhao Xiaofeng Wang Prof. Zheyuan Liu Prof. Yan Yu Prof. Liuyi Li 《Angewandte Chemie (International ed. in English)》2023,62(31):e202307160
Supramolecular systems consisting of covalent organic frameworks (COFs) and Ni complex are designed for robust photocatalytic reduction of CO2. Multiple heteroatom-hydrogen bonding between the COF and Ni complex is identified to play a decisive role in the photoexcited electron transfer across the liquid-solid interface. The diminution of steric groups on COF or metal complex can optimize catalytic performance, which is more attributable to the enhanced hydrogen-bond interaction rather than their intrinsic activity. The photosystem with relatively strong strength of hydrogen bonds exhibits remarkable photocatalytic CO2-to-CO conversion, far superior to photosystems with supported atomic Ni or metal complex alone in the absence of hydrogen-bond effect. Such heteroatom-hydrogen bonds bridging electron transport pathway confers supramolecular system with high photocatalytic performance, providing an avenue to rationally design efficient and steadily available photosystems. 相似文献
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本文以聚甲基丙烯酸甘油酯(PGMA)作为大分子RAFT试剂,甲基丙烯酸羟丙酯(HPMA)和甲基丙烯酸-2-(二甲氨基)乙酯(DMAEMA)作为单体,在室温下通过水相光引发聚合诱导自组装制备CO2响应聚合物囊泡。动力学研究表明聚合在可见光(405nm,0.5 mW/cm2)照射10min后,转化率可以达到100%。文中还探讨了DMAEMA对于聚合反应的影响。通过视觉观察、透射电子显微镜(TEM)以及核磁共振(NMR)对聚合物囊泡的二氧化碳响应特性进行了研究。 相似文献
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Lei Zhang Zichao Wei Srinivas Thanneeru Michael Meng Megan Kruzyk Gaël Ung Ben Liu Jie He 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):15981-15987
The stability of metal nanocatalysts for electrocatalytic CO2 reduction is of key importance for practical application. We report the use of two polymeric N‐heterocyclic carbenes (NHC) (polydentate and monodentate) to stabilize metal nanocatalysts (Au and Pd) for efficient CO2 electroreduction. Compared with other conventional ligands including thiols and amines, metal–carbene bonds that are stable under reductive potentials prevent the nanoclustering of nanoparticles. Au nanocatalysts modified by polymeric NHC ligands show an activity retention of 86 % after CO2 reduction at ?0.9 V for 11 h, while it is less than 10 % for unmodified Au. We demonstrate that the hydrophobicity of polymer ligands and the enriched surface electron density of metal NPs through σ‐donation of NHCs substantially improve the selectivity for CO2 reduction over proton. 相似文献
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Dr. Shan Hu Dr. Panzhe Qiao Dr. Xinli Yi Yiming Lei Huilin Hu Prof. Jinhua Ye Prof. Defa Wang 《Angewandte Chemie (International ed. in English)》2023,62(26):e202304585
Artificial photosynthesis is a promising strategy for converting carbon dioxide (CO2) and water (H2O) into fuels and value-added chemical products. However, photocatalysts usually suffered from low activity and product selectivity due to the sluggish dynamic transfer of photoexcited charge carriers. Herein, we describe anchoring of Ag single atoms on hollow porous polygonal C3N4 nanotubes (PCN) to form the photocatalyst Ag1@PCN with Ag−N3 coordination for CO2 photoreduction using H2O as the reductant. The as-synthesized Ag1@PCN exhibits a high CO production rate of 0.32 μmol h−1 (mass of catalyst: 2 mg), a high selectivity (>94 %), and an excellent stability in the long term. Experiments and density functional theory (DFT) reveal that the strong metal–support interactions (Ag−N3) favor *CO2 adsorption, *COOH generation and desorption, and accelerate dynamic transfer of photoexcited charge carriers between C3N4 and Ag single atoms, thereby accounting for the enhanced CO2 photoreduction activity with a high CO selectivity. This work provides a deep insight into the important role of strong metal–support interactions in enhancing the photoactivity and CO selectivity of CO2 photoreduction. 相似文献
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二氧化碳(CO2)电催化还原反应利用可再生能源将CO2转化为高值燃料和化学品,是一种新型的碳中和技术。CO2电催化还原反应在电极/电解质界面上进行,因此除催化剂以外,电解质对提高CO2电催化还原反应性能同样至关重要。本文深度剖析了CO2电催化还原反应中的电解质效应,结合近几年的最新研究进展,详细讨论了局部p H、阳离子、阴离子和离子交换膜等电解质组成和性质对电催化活性和产物选择性的影响,阐述了电解质效应的催化作用机制。本文特别强调了电化学原位红外/拉曼等振动光谱在电解质效应机理研究方面的优势以及面向实际应用的膜电极CO2电解器中阴离子、阳离子、水、液体产物等物质传输对活性、选择性、能量效率及CO2利用效率等关键催化性能指标的影响。本文最后提出了当前电解质效应研究中存在的挑战,并展望了未来的研究机遇和发展趋势。 相似文献
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Dr. Weixin Zou Yingyi Cheng Dr. Yu-Xin Ye Xiaoqian Wei Dr. Qing Tong Prof. Lin Dong Prof. Gangfeng Ouyang 《Angewandte Chemie (International ed. in English)》2023,62(49):e202313392
Photocatalytic CO2 reduction to CH4 requires photosensitizers and sacrificial agents to provide sufficient electrons and protons through metal-based photocatalysts, and the separation of CH4 from by-product O2 has poor applications. Herein, we successfully synthesize a metal-free photocatalyst of a novel electron-acceptor 4,5,9,10-pyrenetetrone (PT), to our best knowledge, this is the first time that metal-free catalyst achieves non-sacrificial photocatalytic CO2 to CH4 and easily separable H2O2. This photocatalyst offers CH4 product of 10.6 μmol ⋅ g−1 ⋅ h−1 under non-sacrificial ambient conditions (room temperature, and only water), which is two orders of magnitude higher than that of the reported metal-free photocatalysts. Comprehensive in situ characterizations and calculations reveal a multi-step reaction mechanism, in which the long-lived oxygen-centered radical in the excited PT provides as a site for CO2 activation, resulting in a stabilized cyclic carbonate intermediate with a lower formation energy. This key intermediate is thermodynamically crucial for the subsequent reduction to CH4 product with the electronic selectivity of up to 90 %. The work provides fresh insights on the economic viability of photocatalytic CO2 reduction to easily separable CH4 in non-sacrificial and metal-free conditions. 相似文献
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Reversible Phase Transfer of Carbon Dots between an Organic Phase and Aqueous Solution Triggered by CO2
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Xiaoyan Pei Dr. Dazhen Xiong Dr. Huiyong Wang Shuaiqi Gao Prof. Xinying Zhang Prof. Suojiang Zhang Prof. Jianji Wang 《Angewandte Chemie (International ed. in English)》2018,57(14):3687-3691
Carbon dots (CDs) have attracted increasing attention in applications such as bio‐imaging, sensors, catalysis, and drug delivery. However, unlike metallic and semiconductor nanoparticles, the transfer of CDs between polar and non‐polar phases is little understood. A class of amine‐terminated CDs is developed and their phase transfer behavior has been investigated. It is found that these CDs can reversibly transfer between aqueous and organic solvents by alternatively bubbling and removing CO2 at atmospheric pressure. The mechanism of such CO2‐switched phase transfer involves reversible acid–base reaction of amine‐terminated CDs with CO2 and the reversible formation of hydrophilic ammonium salts. By using the CDs as catalysts, the phase transfer is applied in the Knoevenagel reaction for efficient homogeneous reaction, heterogeneous separation, and recycling of the catalysts. 相似文献
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Yu-Jie Wang Dr. Gui-Lin Zhuang Dr. Jiang-Wei Zhang Prof. Fang Luo Xin Cheng Fu-Li Sun Dr. Shan-Shan Fu Prof. Tong-Bu Lu Prof. Zhi-Ming Zhang 《Angewandte Chemie (International ed. in English)》2023,62(6):e202216592
We explored a co-dissolved strategy to embed mono-dispersed Pt center into V2O5 support via dissolving [PtV9O28]7− into [V10O28]6− aqueous solution. The uniform dispersion of [PtV9O28]7− in [V10O28]6− solution allows [PtV9O28]7− to be surrounded by [V10O28]6− clusters via a freeze-drying process. The V centers in both [PtV9O28]7− and [V10O28]6− were converted into V2O5 via a calcination process to stabilize Pt center. These double separations can effectively prevent the Pt center agglomeration during the high-temperature conversion process, and achieve 100 % utilization of Pt in [PtV9O28]7−. The resulting Pt-V2O5 single-atom-site catalysts exhibit a CH4 yield of 247.6 μmol g−1 h−1, 25 times higher than that of Pt nanoparticle on the V2O5 support, which was accompanied by the lactic acid photooxidation to form pyruvic acid. Systematical investigations on this unambiguous structure demonstrate an important role of Pt−O atomic pair synergy for highly efficient CO2 photoreduction. 相似文献
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Ratul Paul Risov Das Nitumani Das Subhajit Chakraborty Chih-Wen Pao Dr. Quang Thang Trinh Dr. G. T. Kasun Kalhara Gunasooriya Dr. John Mondal Prof. Sebastian C. Peter 《Angewandte Chemie (International ed. in English)》2023,62(50):e202311304
Herein, we have specifically designed two metalated porous organic polymers ( Zn-POP and Co-POP ) for syngas (CO+H2) production from gaseous CO2. The variable H2/CO ratio of syngas with the highest efficiency was produced in water medium (without an organic hole scavenger and photosensitizer) by utilizing the basic principle of Lewis acid/base chemistry. Also, we observed the formation of entirely different major products during photocatalytic CO2 reduction and water splitting with the help of the two catalysts, where CO (145.65 μmol g−1 h−1) and H2 (434.7 μmol g−1 h−1) production were preferentially obtained over Co-POP & Zn-POP , respectively. The higher electron density/better Lewis basic nature of Co-POP was investigated further using XPS, XANES, and NH3-TPD studies, which considerably improve CO2 activation capacity. Moreover, the structure–activity relationship was confirmed via in situ DRIFTS and DFT studies, which demonstrated the formation of COOH* intermediate along with the thermodynamic feasibility of CO2 reduction over Co-POP while water splitting occurred preferentially over Zn-POP . 相似文献
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Fucheng Gao Jian Huang Prof. Ying Ruan Prof. Hui Li Pengyu Gong Prof. Fenglong Wang Prof. Qunwei Tang Prof. Yanyan Jiang 《Angewandte Chemie (International ed. in English)》2023,62(7):e202214042
The lack of systematic structural resolution makes it difficult to build specific transition-metal-atom-doped carbonized polymer dots (TMA-doped CPDs). Herein, the structure-activity relationship between Cu atoms and CPDs was evaluated by studying the peroxidase-like properties of Glu−Cu−CPDs prepared by using copper glutamate (Glu) with a Cu−N2O2 initial structure. The results showed that the Cu atoms bound to Glu−Cu−CPDs in the form of Cu−N2C2, indicating that Cu−O bonds changed into Cu−C bonds under hydrothermal conditions. This phenomenon was also observed in other copper-doped CPDs. Moreover, the carboxyl and amino groups content decreased after copper-atom doping. Theoretical calculations revealed a dual-site catalytic mechanism for catalyzing H2O2. The detection of intracellular H2O2 suggested their application prospects. Our study provides an in-depth understanding of the formation and catalytic mechanism of TMA-doped-CPDs, allowing for the generation specific TMA-doped-CPDs. 相似文献
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Li‐Yuan Wu Yan‐Fei Mu Xiao‐Xuan Guo Wen Zhang Zhi‐Ming Zhang Min Zhang Tong‐Bu Lu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(28):9591-9595
Improving the stability of lead halide perovskite quantum dots (QDs) in a system containing water is the key for their practical application in artificial photosynthesis. Herein, we encapsulate low‐cost CH3NH3PbI3 (MAPbI3) perovskite QDs in the pores of earth‐abundant Fe‐porphyrin based metal organic framework (MOF) PCN‐221(Fex) by a sequential deposition route, to construct a series of composite photocatalysts of MAPbI3@PCN‐221(Fex) (x=0–1). Protected by the MOF the composite photocatalysts exhibit much improved stability in reaction systems containing water. The close contact of QDs to the Fe catalytic site in the MOF, allows the photogenerated electrons in the QDs to transfer rapidly the Fe catalytic sites to enhance the photocatalytic activity for CO2 reduction. Using water as an electron source, MAPbI3@PCN‐221(Fe0.2) exhibits a record‐high total yield of 1559 μmol g?1 for photocatalytic CO2 reduction to CO (34 %) and CH4 (66 %), 38 times higher than that of PCN‐221(Fe0.2) in the absence of perovskite QDs. 相似文献
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利用可见光将二氧化碳光还原为有用的化学品是一项有前景但充满挑战的工作. 金属有机骨架(MOFs)作为一种新兴的具高孔隙率、高比表面积、强吸附富集CO2能力、结构和功能可调的多孔材料, 在光催化二氧化碳还原反应中具有极强的应用潜力. 但大多数金属有机骨架材料存在可见光吸收范围窄、光生载流子快速复合等问题, 导致催化二氧化碳还原活性仍然较低. 通过静电自组装策略将纳米级胺基化金属有机骨架材料(NH2-MIL-88B(Fe))和羧酸化石墨烯量子点(GQD)通过静电作用结合, 得到GQD/NH2-MIL-88B(Fe)复合材料. 该复合催化剂有效结合了金属有机骨架强二氧化碳吸附富集能力和GQD的可见光吸收范围宽、电子传导能力强等优点, 因此与纯金属有机骨架材料NH2- MIL-88B(Fe)相比较, 该复合材料能高效光催化还原CO2为CO, 并在10 h可见光下活性高达590 μmol/g, 约为NH2-MIL-88B(Fe)活性的四倍. 这项工作为制备高活性催化CO2的金属有机骨架复合材料提供了借鉴. 相似文献
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Zhihe Wei Yanhui Su Weiyi Pan Junxia Shen Ronglei Fan Wenjun Yang Zhao Deng Mingrong Shen Yang Peng 《Angewandte Chemie (International ed. in English)》2023,62(28):e202305558
Silicon semiconductor functionalized with molecular catalysts emerges as a promising cathode for photoelectrochemical (PEC) CO2 reduction reaction (CO2RR). However, the limited kinetics and stabilities remains a major hurdle for the development of such composites. We herein report an assembling strategy of silicon photocathodes via chemically grafting a conductive graphene layer onto the surface of n+-p Si followed by catalyst immobilization. The covalently-linked graphene layer effectively enhances the photogenerated carriers transfer between the cathode and the reduction catalyst, and improves the operating stability of the electrode. Strikingly, we demonstrate that altering the stacking configuration of the immobilized cobalt tetraphenylporphyrin (CoTPP) catalyst through calcination can further enhance the electron transfer rate and the PEC performance. At the end, the graphene-coated Si cathode immobilized with CoTPP catalyst managed to sustain a stable 1-Sun photocurrent of −1.65 mA cm−2 over 16 h for CO production in water at a near neutral potential of −0.1 V vs. reversible hydrogen electrode. This represents a remarkable improvement of PEC CO2RR performance in contrast to the reported photocathodes functionalized with molecular catalysts. 相似文献