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1.
Xingzhong Yuan Hou Wang Yan Wu Guangming Zeng Xiaohong Chen Lijian Leng Zhibin Wu Hui Li 《应用有机金属化学》2016,30(5):289-296
In recent years, tremendous research efforts have been made towards developing metal–organic framework (MOF)‐based composites for photocatalytic applications. In this work, bipyramid‐like MIL‐125(Ti) frustum enwrapped with reduced graphene oxide (rGO) and dispersed silver nanoparticles (Ag NPs) was fabricated using an efficient one‐pot self‐assembly and photoreduction strategy. The as‐obtained materials were characterized using field emission scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, nitrogen adsorption–desorption isotherms, and X‐ray photoelectron, ultraviolet–visible diffuse reflectance and photoluminescence spectroscopies. It is found that the as‐prepared Ag/rGO/MIL‐125(Ti) ternary hybrids have large surface area, microporous structure, enhanced visible light absorption and prolonged lifetime of charge carriers. Compared with pure MIL‐125(Ti) and its binary counterparts, the ternary composite exhibits more efficient photocatalytic performance for Rhodamine B (RhB) degradation from water under visible light irradiation. The photodegradation rate of RhB on Ag/rGO/MIL‐125(Ti) is 0.0644 min?1, which is 1.62 times higher than that of the pure MIL‐125(Ti). The improved photocatalytic performance is ascribed to the indirect dye photosensitization, the Ag NP localized surface plasmon resonance, the Ti3+–Ti4+ intervalence electron transfer and the synergistic effect among MIL‐125(Ti), Ag NPs and rGO. Ag NPs serve as an efficient ‘electron reservoir’ and rGO as an electron transporter and collector. Therefore, this work provides a new pathway into the design of MOF‐based composites for application in environmental and energy fields. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
2.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(28):8270-8274
The double perovskite family, A2MIMIIIX6, is a promising route to overcome the lead toxicity issue confronting the current photovoltaic (PV) standout, CH3NH3PbI3. Given the generally large indirect band gap within most known double perovskites, band‐gap engineering provides an important approach for targeting outstanding PV performance within this family. Using Cs2AgBiBr6 as host, band‐gap engineering through alloying of InIII/SbIII has been demonstrated in the current work. Cs2Ag(Bi1−x Mx )Br6 (M=In, Sb) accommodates up to 75 % InIII with increased band gap, and up to 37.5 % SbIII with reduced band gap; that is, enabling ca. 0.41 eV band gap modulation through introduction of the two metals, with smallest value of 1.86 eV for Cs2Ag(Bi0.625Sb0.375)Br6. Band structure calculations indicate that opposite band gap shift directions associated with Sb/In substitution arise from different atomic configurations for these atoms. Associated photoluminescence and environmental stability of the three‐metal systems are also assessed. 相似文献
3.
Jun‐Hao Wang Sheng‐Zheng Huang Shan‐Shan Yang Yun‐Long Chen Ya‐Meng Wu Na‐Na Li Xi‐Yan Dong Fei‐Fei Li 《无机化学与普通化学杂志》2019,645(10):706-711
Porous metal‐organic frameworks (MOFs) loading metal nanoparticles to form a composite photocatalyst demonstrated unique advantages. Modification of the electron donating group on the aromatic linkers of MOFs could increase the absorption range of light, thereby increasing the photocatalytic activity. In this study, we prepared a composite photocatalyst using a stable NH2‐functionalized MOF (UiO‐66‐NH2) to load semiconductor Ag/AgBr nanoparticles, and the resultant composites have intense optical absorption throughout visible light range. The greatly enhanced optical absorption and the unique hetero‐junction between Ag/AgBr and UiO‐66‐NH2 render efficient separation and utilization of photogenerated electron‐hole pairs. Therefore, Ag/AgBr@UiO‐66‐NH2 showed much more excellent photocatalytic activity, compared with unmodified UiO‐66 loading Ag/AgBr (Ag/AgBr@UiO‐66) and reported AgX@MOF catalysts. Moreover, the composite photocatalysts showed excellent stability during cycling experiment. 相似文献
4.
《Surface and interface analysis : SIA》2018,50(2):146-153
Tungsten and nitrogen co‐doped TiO2 nanobelts (W/N‐TNBs) have been successfully synthesized via 1‐step hydrothermal method. The structure, morphology, and composition of prepared samples were characterized by X‐ray diffraction, scanning electron microscopy, and X‐ray photoelectron spectroscopy, respectively. The prominent phase of all as‐prepared samples is anatase crystal. For samples with N doping, new energy states can be introduced on top of O 2p states which reduced the band gap by 1.1 eV. The reduced band gap leads to efficient visible light activity. The 3%‐W/N‐TNBs were found to exhibit the highest activity. The photocatalytic performance of 3%‐W/N‐TNBs under visible light is about 4.8 times than that of pure TiO2 nanobelts, which emphasizes the synergistic effect of W and N co‐doping for effectively inhibiting the recombination of photogenerated electrons and holes. In addition, our results testify the different redox potentials of the photoelectrons at different final states. 相似文献
5.
Ag/mesoporous black TiO2 nanotubes heterojunctions (Ag‐MBTHs) were fabricated through a surface hydrogenation, wet‐impregnation and photoreduction strategy. The as‐prepared Ag‐MBTHs possess a relatively high specific surface area of ≈85 m2 g?1 and an average pore size of ≈13.2 nm. The Ag‐MBTHs with a narrow band gap of ≈2.63 eV extend the photoresponse from UV to the visible‐light and near‐infrared (NIR) region. They exhibit excellent visible‐NIR‐driven photothermal catalytic and photocatalytic performance for complete conversion of nitro aromatic compounds (100 %) and mineralization of highly toxic phenol (100 %). The enhancement can be attributed to the mesoporous hollow structures increasing the light multi‐refraction, the Ti3+ in frameworks and the surface plasmon resonance (SPR) effect of plasmonic Ag nanoparticles favoring light‐harvesting and spatial separation of photogenerated electron–hole pairs, which is confirmed by transient fluorescence. The fabrication of this SPR‐enhanced visible‐NIR‐driven Ag‐MBTHs catalyst may provide new insights for designing other high‐performance heterojunctions as photocatalytic and photothermal catalytic nanomaterials. 相似文献
6.
Zhi‐Lei Wu Chang‐Hong Wang Prof. Dr. Bin Zhao Jie Dong Dr. Feng Lu Dr. Wei‐Hua Wang Prof. Dr. Wei‐Chao Wang Dr. Guang‐Jun Wu Prof. Dr. Jian‐Zhong Cui Prof. Dr. Peng Cheng 《Angewandte Chemie (International ed. in English)》2016,55(16):4938-4942
Based on the newly designed ligand 4′‐(3,5‐dicarboxyphenyl)‐4,2′:6′,4′′‐terpyridine (DCTP), a unique semi‐conductive 3D framework {[CuΙCuΙΙ2(DCTP)2]NO3?1.5 DMF}n ( 1 ) with a narrow band gap of 2.1 eV, was obtained and structurally characterized. DFT calculations with van de Waals correction employed to explore the electronic structure of 1 , clearly revealed its semi‐conductive behavior. Furthermore, we found that 1 exhibits a superior band alignment with water to produce hydrogen and degrade organic pollutants. Without adding any photosensitizers, 1 displays an efficiently photocatalytic hydrogen production in water based on the photo‐generated electrons under UV/Vis light. 1 also exhibits excellent photo‐degradation of methyl blue under visible‐light owing to the strong oxidization of excited holes. It is the first example of MOFs with doubly photocatalytic activities related to photo‐generated electrons and holes, respectively. 相似文献
7.
Introducing plasmonic metals into semiconductor materials has been proven to be an attractive strategy for enhancing photocatalytic activity in the visible region. In this work, a novel and efficient Ag/Ag2WO4/g‐C3N4 (AACN) ternary plasmonic photocatalyst was successfully synthesized using a facile one‐step in situ hydrothermal method. The composition, structure, morphology and optical absorption properties of AACN were investigated using X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and UV–visible diffuse reflectance spectroscopy, respectively. Photocatalytic performance of AACN was evaluated via rhodamine B and tetracycline degradation. The results indicated that AACN had excellent photocatalytic performance for rhodamine B degradation with a rate constant of 0.0125 min?1, which was higher than those of Ag2WO4 and Ag/Ag2WO4. Characterization and photocatalytic tests showed that the strong coupling effect between the Ag/Ag2WO4 nanoparticles and the exfoliated ultrathin g‐C3N4 nanosheets was superior for visible‐light responsivity and reduced the recombination rate of photogenerated electrons and holes. A proposed mechanism is also discussed according to the band energy structure and the experimental results. 相似文献
8.
The recent discovery of Ag@AgX (X=Cl, Br, I) plasmonic photocatalysts motivates us to elucidate the origin of the higher photocatalytic performance compared to commonly used TiO2‐based materials. Herein, the electronic structure and effective masses of electrons at the conduction band minimum (CBM) and holes at the valence band maximum (VBM) are studied along different directions in the silver halide for the first time by means of first‐principles calculations. It is revealed that the smaller effective mass of electrons at the CBM in silver halides contributes to the higher photocatalytic performance. The remarkable dependence of the effective mass of holes on the direction and the anion of the silver halide explains well the experimental observed morphology and anion dependence of photocatalytic activities of Ag@AgX. The crystal field splitting of the Ag 4d bands in the valance band of silver halides is found to be a main factor leading to the large effective mass of the photogenerated holes and consequently to a weaker transfer ability. A new crystal design and exerting strain along the coordinate axis are proposed as solutions to decrease the effective mass of holes. The present work may be helpful in exploring this novel class of silver halide‐based photocatalysts. 相似文献
9.
Noble Metals Can Have Different Effects on Photocatalysis Over Metal–Organic Frameworks (MOFs): A Case Study on M/NH2‐MIL‐125(Ti) (M=Pt and Au) 下载免费PDF全文
Dengrong Sun Wenjun Liu Dr. Yanghe Fu Zhenxing Fang Fangxiang Sun Prof. Dr. Xianzhi Fu Prof. Dr. Yongfan Zhang Prof. Dr. Zhaohui Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(16):4780-4788
M‐doped NH2‐MIL‐125(Ti) (M=Pt and Au) were prepared by using the wetness impregnation method followed by a treatment with H2 flow. The resultant samples were characterized by powder X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), X‐ray absorption fine structure (XAFS) analyses, N2‐sorption BET surface area, and UV/Vis diffuse reflectance spectroscopy (DRS). The photocatalytic reaction carried out in saturated CO2 with triethanolamine (TEOA) as sacrificial agent under visible‐light irradiations showed that the noble metal‐doping on NH2‐MIL‐125(Ti) promoted the photocatalytic hydrogen evolution. Unlike that over pure NH2‐MIL‐125(Ti), in which only formate was produced, both hydrogen and formate were formed over Pt‐ and Au‐loaded NH2‐MIL‐125(Ti). However, Pt and Au have different effects on the photocatalytic performance for formate production. Compared with pure NH2‐MIL‐125(Ti), Pt/NH2‐MIL‐125(Ti) showed an enhanced activity for photocatalytic formate formation, whereas Au has a negative effect on this reaction. To elucidate the origin of the different photocatalytic performance, electron spin resonance (ESR) analyses and density functional theory (DFT) calculations were carried out over M/NH2‐MIL‐125(Ti).The photocatalytic mechanisms over M/NH2‐MIL‐125(Ti) (M=Pt and Au) were proposed. For the first time, the hydrogen spillover from the noble metal Pt to the framework of NH2‐MIL‐125(Ti) and its promoting effect on the photocatalytic CO2 reduction is revealed. The elucidation of the mechanism on the photocatalysis over M/NH2‐MIL‐125(Ti) can provide some guidance in the development of new photocatalysts based on MOF materials. This study also demonstrates the potential of using noble metal‐doped MOFs in photocatalytic reactions involving hydrogen as a reactant, like hydrogenation reactions. 相似文献
10.
The surface modification of Ag/Ag2CO3 with Fe(III) ions has been achieved through simply photoreduction‐impregnation method. The obtained products were characterized by means of X‐ray diffraction (XRD), scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), and UV‐vis absorption spectroscopy. Under visible‐light irradiation (γ>420 nm), the Fe(III)/Ag/Ag2CO3 sample displays a higher photocatalytic activity and stability than pure Ag2CO3 and Ag/Ag2CO3 samples for the degradation of methyl orange (MO). The improved photocatalytic activity and stability of this ternary system could be ascribed to the synergetic effect between Ag nanoparticles and Fe(III) nanocluster. The metallic Ag nanoparticles cause an obviously enhanced visible‐light absorption to produce more photogenerated charges, while the Fe(III) works as an active site for the following oxygen reduction to reduce the recombination rate of photogenerated electrons and holes. 相似文献
11.
Dengrong Sun Dr. Yanghe Fu Wenjun Liu Lin Ye Dengke Wang Lin Yang Prof. Dr. Xianzhi Fu Prof. Dr. Zhaohui Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(42):14279-14285
Metal–organic framework (MOF) NH2‐Uio‐66(Zr) exhibits photocatalytic activity for CO2 reduction in the presence of triethanolamine as sacrificial agent under visible‐light irradiation. Photoinduced electron transfer from the excited 2‐aminoterephthalate (ATA) to Zr oxo clusters in NH2‐Uio‐66(Zr) was for the first time revealed by photoluminescence studies. Generation of ZrIII and its involvement in photocatalytic CO2 reduction was confirmed by ESR analysis. Moreover, NH2‐Uio‐66(Zr) with mixed ATA and 2,5‐diaminoterephthalate (DTA) ligands was prepared and shown to exhibit higher performance for photocatalytic CO2 reduction due to its enhanced light adsorption and increased adsorption of CO2. This study provides a better understanding of photocatalytic CO2 reduction over MOF‐based photocatalysts and also demonstrates the great potential of using MOFs as highly stable, molecularly tunable, and recyclable photocatalysts in CO2 reduction. 相似文献
12.
Photocatalytic reactions are governed by photogenerated charge carriers upon band gap excitation. Therefore, for better understanding of the mechanism, the dynamics of photocarriers should be studied. One of the attractive materials is TiO2, which has been extensively investigated in the field of photocatalysis. This review article summarizes our recent works of time-resolved visible to mid-IR absorption measurements to elucidate the difference of anatase, rutile, and brookite TiO2 powders. The distinctive photocatalytic activities of these polymorphs are determined by the electron-trapping processes at the defects on powders. Powders are rich in defects and these defects capture photogenerated electrons. The depth of the trap is crystal phase dependent, and they are estimated to be < 0.1 eV, ∼0.4 eV and ∼0.9 eV for anatase, brookite, and rutile, respectively. Electron trapping reduces probability to meet with holes and then elongate the lifetime of holes. Therefore, it works negatively for the reaction of electrons but positively works for the reaction of holes. In the steady-state reactions, both electrons and holes should be consumed. Hence, the balance between the positive and negative effects of defects determines the distinctive photocatalytic activities of anatase, rutile, and brookite TiO2 powders. 相似文献
13.
Efficient Visible‐Light‐Driven Carbon Dioxide Reduction by a Single‐Atom Implanted Metal–Organic Framework 下载免费PDF全文
Dr. Huabin Zhang Dr. Jing Wei Dr. Juncai Dong Dr. Guigao Liu Li Shi Dr. Pengfei An Dr. Guixia Zhao Dr. Jintao Kong Dr. Xiaojun Wang Dr. Xianguang Meng Prof. Jing Zhang Prof. Jinhua Ye 《Angewandte Chemie (International ed. in English)》2016,55(46):14310-14314
Modular optimization of metal–organic frameworks (MOFs) was realized by incorporation of coordinatively unsaturated single atoms in a MOF matrix. The newly developed MOF can selectively capture and photoreduce CO2 with high efficiency under visible‐light irradiation. Mechanistic investigation reveals that the presence of single Co atoms in the MOF can greatly boost the electron–hole separation efficiency in porphyrin units. Directional migration of photogenerated excitons from porphyrin to catalytic Co centers was witnessed, thereby achieving supply of long‐lived electrons for the reduction of CO2 molecules adsorbed on Co centers. As a direct result, porphyrin MOF comprising atomically dispersed catalytic centers exhibits significantly enhanced photocatalytic conversion of CO2, which is equivalent to a 3.13‐fold improvement in CO evolution rate (200.6 μmol g?1 h?1) and a 5.93‐fold enhancement in CH4 generation rate (36.67 μmol g?1 h?1) compared to the parent MOF. 相似文献
14.
Chang Liu Dr. Xiguang Han Shuifen Xie Prof. Qin Kuang Xue Wang Dr. Mingshang Jin Prof. Zhaoxiong Xie Prof. Lansun Zheng 《化学:亚洲杂志》2013,8(1):282-289
Recently, it has been proven that directional flow of photogenerated charge carriers occurs on specific facets of TiO2 nanocrystals. Herein, we demonstrate that the photocatalytic activity of anatase TiO2 nanocrystals in both photoreduction and photooxidation processes can be enhanced by selectively depositing Pt nanoparticles on the {101} facets, which strengthens spontaneously surface‐induced separation between photogenerated electrons and holes in the photocatalysis process. An optimal ratio of the oxidative {001} facets to the reductive {101} facets exists with regard to the photocatalysis of the faceted TiO2 nanocrystals, and this is crucial for balancing the recombination and redox reaction rates of photogenerated electrons and holes. The present work might help us gain deeper insight into the relation between the specific surface of semiconductor photocatalysts and their photocatalytic activities and provides us with a new route to design photocatalysts with high photocatalytic activity. 相似文献
15.
16.
AgBi(WO4)2: A New Modification Material to Bi2WO6 for Enhanced and Stable Visible‐Light Photocatalyic Performance 下载免费PDF全文
Cuiyun Feng Dr. Yuming Dong Prof. Dr. Pingping Jiang Dr. Guangli Wang Jingjing Zhang Xiuming Wu Prof. Dr. Chi Zhang 《化学:亚洲杂志》2015,10(9):1948-1952
In this work, we report a novel AgBi(WO4)2–Bi2WO6 heterostructure, which was designed and synthesized by using a simple hydrothermal method. Methyl orange was used as a representative dye indicator to evaluate the visible‐light catalytic activity and the catalytic mechanism was investigated. The as‐synthesized AgBi(WO4)2–Bi2WO6 composite displayed a 43 times higher photocatalytic activity than Bi2WO6. Owing to the matched band gap and distinctive heterostructure, AgBi(WO4)2–Bi2WO6 reveals a high visible‐light response and high‐efficiency utilization of both photogenerated electrons and holes. AgBi(WO4)2 reveals a similar energy level to and good lattice match with Bi2WO6, which are favorable qualities for band bending and fluent electron transfer. Furthermore, the photoexcited electrons can produce oxygen to generate .O2? radicals, which is vital for the overall utilization of both holes and electrons. This is the first example of AgBi(WO4)2 being used as photocatalytic material. 相似文献
17.
Dr. Ke-zhao Du Dr. Weiwei Meng Dr. Xiaoming Wang Prof. Yanfa Yan Prof. David B. Mitzi 《Angewandte Chemie (International ed. in English)》2017,56(28):8158-8162
The double perovskite family, A2MIMIIIX6, is a promising route to overcome the lead toxicity issue confronting the current photovoltaic (PV) standout, CH3NH3PbI3. Given the generally large indirect band gap within most known double perovskites, band-gap engineering provides an important approach for targeting outstanding PV performance within this family. Using Cs2AgBiBr6 as host, band-gap engineering through alloying of InIII/SbIII has been demonstrated in the current work. Cs2Ag(Bi1−xMx)Br6 (M=In, Sb) accommodates up to 75 % InIII with increased band gap, and up to 37.5 % SbIII with reduced band gap; that is, enabling ca. 0.41 eV band gap modulation through introduction of the two metals, with smallest value of 1.86 eV for Cs2Ag(Bi0.625Sb0.375)Br6. Band structure calculations indicate that opposite band gap shift directions associated with Sb/In substitution arise from different atomic configurations for these atoms. Associated photoluminescence and environmental stability of the three-metal systems are also assessed. 相似文献
18.
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
19.
《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(46):14829-14833
As the first example of a photocatalytic system for splitting water without additional cocatalysts and photosensitizers, the comparatively cost‐effective Cu2I2‐based MOF, Cu‐I‐bpy (bpy=4,4′‐bipyridine) exhibited highly efficient photocatalytic hydrogen production (7.09 mmol g−1 h−1). Density functional theory (DFT) calculations established the electronic structures of Cu‐I‐bpy with a narrow band gap of 2.05 eV, indicating its semiconductive behavior, which is consistent with the experimental value of 2.00 eV. The proposed mechanism demonstrates that Cu2I2 clusters of Cu‐I‐bpy serve as photoelectron generators to accelerate the copper(I) hydride interaction, providing redox reaction sites for hydrogen evolution. The highly stable cocatalyst‐free and self‐sensitized Cu‐I‐bpy provides new insights into the future design of cost‐effective d10‐based MOFs for highly efficient and long‐term solar fuels production. 相似文献
20.
Xiaolang Chen Shuning Xiao Hao Wang Wenchao Wang Yong Cai Guisheng Li Minghua Qiao Jian Zhu Hexing Li Dieqing Zhang Yunfeng Lu 《Angewandte Chemie (International ed. in English)》2020,59(39):17182-17186
Highly effective photocatalysts for the hydrogen‐evolution reaction were developed by conferring the linkers of NH2‐MIL‐125(Ti), a metal–organic framework (MOF) constructed from TiOx clusters and 2‐aminoterephthalic acid (linkers), with active copper centers. This design enables effective transfer of electrons from the linkers to the transient Cu2+/Cu+ centers, leading to 7000‐fold and 27‐fold increase of carrier density and lifetime of photogenerated charges, respectively, as well as high‐rate production of H2 under visible‐light irradiation. This work provides a novel design of a photocatalyst for hydrogen evolution using non‐noble Cu2+/Cu+ as co‐catalysts. 相似文献