Cheng Wang - Cochemist

Electron Crystallography Reveals Atomic Structures of Metal–Organic Nanoplates with M12(μ3-O)8(μ3-OH)8(μ2-OH)6 (M = Zr, Hf) Secondary Building Units

Co-reporter:Ruihan Dai, Fei Peng, Pengfei Ji, Kuangda Lu, Cheng Wang, Junliang Sun, and Wenbin Lin

Inorganic Chemistry July 17, 2017 Volume 56(Issue 14) pp:8128-8128

Publication Date(Web):June 22, 2017

DOI:10.1021/acs.inorgchem.7b00845

Nanoscale metal–organic frameworks (nMOFs) have shown tremendous potential in cancer therapy and biomedical imaging. However, their small dimensions present a significant challenge in structure determination by single-crystal X-ray crystallography. We report here the structural determination of nMOFs by rotation electron diffraction (RED). Two isostructural Zr- and Hf-based nMOFs with linear biphenyldicarboxylate (BPDC) or bipyridinedicarboxylate (BPYDC) linkers are stable under intense electron beams to allow the collection of high-quality RED data, which reveal a MOF structure with M12(μ3-O)8(μ3-OH)8(μ2-OH)6 (M = Zr, Hf) secondary building units (SBUs). The nMOF structures differ significantly from their UiO bulk counterparts with M6(μ3-O)4(μ3-OH)4 SBUs and provide the foundation for clarifying the structures of a series of previously reported nMOFs with significant potential in cancer therapy and biological imaging. Our work clearly demonstrates the power of RED in determining nMOF structures and elucidating the formation mechanism of distinct nMOF morphologies.

Frontispiz: Surface Modification of Two-Dimensional Metal–Organic Layers Creates Biomimetic Catalytic Microenvironments for Selective Oxidation

Co-reporter:Wenjie Shi;Lingyun Cao;Hua Zhang;Xin Zhou;Bing An;Zekai Lin;Ruihan Dai; Jianfeng Li; Cheng Wang; Wenbin Lin

Angewandte Chemie 2017 Volume 129(Issue 33) pp:

Publication Date(Web):2017/08/07

DOI:10.1002/ange.201783361

Biomimetische KatalyseC. Wang, W. Lin et al. beschreiben in ihrer Zuschrift auf S. 9836 zweidimensionale Metall-organische Schichten mit katalytischen FeII-Zentren, die Oxidase-Enzyme bei der aeroben Photooxidation von Tetrahydrofuran nachahmen.

Surface Modification of Two-Dimensional Metal–Organic Layers Creates Biomimetic Catalytic Microenvironments for Selective Oxidation

Co-reporter:Wenjie Shi;Lingyun Cao;Hua Zhang;Xin Zhou;Bing An;Zekai Lin;Ruihan Dai; Jianfeng Li; Cheng Wang; Wenbin Lin

Angewandte Chemie International Edition 2017 Volume 56(Issue 33) pp:9704-9709

Publication Date(Web):2017/08/07

DOI:10.1002/anie.201703675

AbstractMicroenvironments in enzymes play crucial roles in controlling the activities and selectivities of reaction centers. Herein we report the tuning of the catalytic microenvironments of metal–organic layers (MOLs), a two-dimensional version of metal–organic frameworks (MOFs) with thickness down to a monolayer, to control product selectivities. By modifying the secondary building units (SBUs) of MOLs with monocarboxylic acids, such as gluconic acid, we changed the hydrophobicity/hydrophilicity around the active sites and fine-tuned the selectivity in photocatalytic oxidation of tetrahydrofuran (THF) to exclusively afford butyrolactone (BTL), likely a result of prolonging the residence time of reaction intermediates in the hydrophilic microenvironment of catalytic centers. Our work highlights new opportunities in using functional MOLs as highly tunable and selective two-dimensional catalytic materials.

Frontispiece: Surface Modification of Two-Dimensional Metal–Organic Layers Creates Biomimetic Catalytic Microenvironments for Selective Oxidation

Co-reporter:Wenjie Shi;Lingyun Cao;Hua Zhang;Xin Zhou;Bing An;Zekai Lin;Ruihan Dai; Jianfeng Li; Cheng Wang; Wenbin Lin

Angewandte Chemie International Edition 2017 Volume 56(Issue 33) pp:

Publication Date(Web):2017/08/07

DOI:10.1002/anie.201783361

Biomimetic CatalysisC. Wang, W. Lin, et al. show in their Communication on page 9704 ff. that two-dimensional metal–organic layers (MOLs) with FeII catalytic centers mimic oxidase enzymes in the aerobic photo-oxidization of tetrahydrofuran.

Surface Modification of Two-Dimensional Metal–Organic Layers Creates Biomimetic Catalytic Microenvironments for Selective Oxidation

Co-reporter:Wenjie Shi;Lingyun Cao;Hua Zhang;Xin Zhou;Bing An;Zekai Lin;Ruihan Dai; Jianfeng Li; Cheng Wang; Wenbin Lin

Angewandte Chemie 2017 Volume 129(Issue 33) pp:9836-9841

Publication Date(Web):2017/08/07

DOI:10.1002/ange.201703675

AbstractMicroenvironments in enzymes play crucial roles in controlling the activities and selectivities of reaction centers. Herein we report the tuning of the catalytic microenvironments of metal–organic layers (MOLs), a two-dimensional version of metal–organic frameworks (MOFs) with thickness down to a monolayer, to control product selectivities. By modifying the secondary building units (SBUs) of MOLs with monocarboxylic acids, such as gluconic acid, we changed the hydrophobicity/hydrophilicity around the active sites and fine-tuned the selectivity in photocatalytic oxidation of tetrahydrofuran (THF) to exclusively afford butyrolactone (BTL), likely a result of prolonging the residence time of reaction intermediates in the hydrophilic microenvironment of catalytic centers. Our work highlights new opportunities in using functional MOLs as highly tunable and selective two-dimensional catalytic materials.

Electrocatalytic reduction of CO2 to CO with 100% faradaic efficiency by using pyrolyzed zeolitic imidazolate frameworks supported on carbon nanotube networks

Co-reporter:Ying Guo;Huijuan Yang;Xin Zhou;Kunlong Liu;Chao Zhang;Zhiyou Zhou;Wenbin Lin

Journal of Materials Chemistry A 2017 vol. 5(Issue 47) pp:24867-24873

Publication Date(Web):2017/12/05

DOI:10.1039/C7TA08431E

Electrochemical reduction of CO2 has received much attention because of its potential in converting atmospheric CO2 into commodity products. One of the key challenges in electrochemical CO2 reduction is the competing hydrogen evolution reaction (HER) at reduction electrode potentials. In this work, we used a hybrid material composed of pyrolyzed zeolitic imidazolate frameworks (ZIFs) and multi-walled carbon nanotubes (MWCNTs) to selectively catalyze electrochemical reduction of CO2 to CO in aqueous solution with close to 100% faradaic efficiency and a current density up to 7.7 mA cm−2 at an overpotential of 740 mV. The MWCNT support is crucial to achieving superior selectivity, thanks to enhanced electron transport on the MWCNT network and expedited CO2 transport in the mesoporous structure constructed by the MWCNTs. Moreover, doping Fe into the hybrid further reduces the overpotential of CO2 reduction to 440 mV with a current density of 2 mA cm−2 and a CO faradaic efficiency of 97%. This work highlights the importance of optimizing electron and mass transport in turning moderate catalysts into superior ones with high activity and selectivity for CO2 reduction.

Through-space Förster-type energy transfer in isostructural zirconium and hafnium-based metal–organic layers

Co-reporter:Zi Wang;Yuxiu Liu;Zhiye Wang;Lingyun Cao;Yi Zhao;Wenbin Lin

Chemical Communications 2017 vol. 53(Issue 67) pp:9356-9359

Publication Date(Web):2017/08/17

DOI:10.1039/C7CC03464D

Quantitative determination of energy transfer in isostructural Zr and Hf metal–organic layers (MOLs) by measuring fluorescence quenching upon doping the MOLs with a quencher or modifying the MOLs with a coumarin-343 dye revealed nearly identical energy transfer rates of the two MOLs, consistent with the dominance of through-space Förster-type energy transfer.

Pyrolysis of metal–organic frameworks to hierarchical porous Cu/Zn-nanoparticle@carbon materials for efficient CO2 hydrogenation

Co-reporter:Jingzheng Zhang;Bing An;Yahui Hong;Yaping Meng;Xuefu Hu;Jingdong Lin;Wenbin Lin;Yong Wang

Materials Chemistry Frontiers 2017 vol. 1(Issue 11) pp:2405-2409

Publication Date(Web):2017/10/26

DOI:10.1039/C7QM00328E

Conversion of CO2 to CO via hydrogenation, also known as the reverse water-gas shift (RWGS) reaction, is an important chemical process to generate CO as a platform chemical for further conversions. Metallic Cu catalyses the RWGS reaction at a temperature of 500 °C with a high initial turnover frequency, but surface structural reorganization and particle growth at the reaction temperature deleteriously reduce its activity over time. In this work, we synthesized hierarchical structures of porous Cu@C and Cu/Zn@C materials via pyrolysis of Cu-BTC Metal–Organic Frameworks (MOFs) with or without Zn doping. Carbon encapsulation protects the Cu NPs from sintering, leading to stable catalytic activity at 500 °C under which RWGS is favored. Furthermore, the final catalyst pellet size can be controlled by tuning the crystal size of MOF precursors, eliminating the step of forming catalysts for fixed bed reactor applications.

Förster Energy Transport in Metal–Organic Frameworks Is Beyond Step-by-Step Hopping

Co-reporter:Qiongqiong Zhang; Cankun Zhang; Lingyun Cao; Zi Wang; Bing An; Zekai Lin; Ruiyun Huang; Zhiming Zhang; Cheng Wang;Wenbin Lin

Journal of the American Chemical Society 2016 Volume 138(Issue 16) pp:5308-5315

Publication Date(Web):March 25, 2016

DOI:10.1021/jacs.6b01345

Metal–organic frameworks (MOFs) with light-harvesting building blocks designed to mimic photosynthetic chromophore arrays in green plants provide an excellent platform to study exciton transport in networks with well-defined structures. A step-by-step exciton random hopping model made of the elementary steps of energy transfer between only the nearest neighbors is usually used to describe the transport dynamics. Although such a nearest neighbor approximation is valid in describing the energy transfer of triplet states via the Dexter mechanism, we found it inadequate in evaluating singlet exciton migration that occurs through the Förster mechanism, which involves one-step jumping over longer distance. We measured migration rates of singlet excitons on two MOFs constructed from truxene-derived ligands and zinc nodes, by monitoring energy transfer from the MOF skeleton to a coumarin probe in the MOF cavity. The diffusivities of the excitons on the frameworks were determined to be 1.8 × 10–2 cm2/s and 2.3 × 10–2 cm2/s, corresponding to migration distances of 43 and 48 nm within their lifetimes, respectively. “Through space” energy-jumping beyond nearest neighbor accounts for up to 67% of the energy transfer rates. This finding presents a new perspective in the design and understanding of highly efficient energy transport networks for singlet excited states.

Pyrolysis of Metal–Organic Frameworks to Fe3O4@Fe5C2 Core–Shell Nanoparticles for Fischer–Tropsch Synthesis

Co-reporter:Bing An, Kang Cheng, Cheng Wang, Ye Wang, and Wenbin Lin

ACS Catalysis 2016 Volume 6(Issue 6) pp:3610

Publication Date(Web):April 19, 2016

DOI:10.1021/acscatal.6b00464

We prepared highly active catalysts for Fischer–Tropsch (FT) synthesis through the pyrolysis of iron-containing metal–organic frameworks (MOFs). The Fe-time yields of the nitrogen-doped catalyst were as high as 720 μmolCO gFe–1 s–1 under the conditions of 300 °C, 2 MPa, and H2/CO = 1, which is a value that surpasses that of most FT catalysts reported in the literature. The pyrolysis of the MOFs yielded nanoparticles with a unique iron oxide@iron carbide core–shell structure dispersed on carbon supports. Such a structure is favorable for FT synthesis and has never been reported previously. Our strategy resolved the problem that the strong metal–support interactions that are usually required to stabilize dispersed particles in calcination compromise the catalytic activity, because of the difficulty of reducing metal oxides. Moreover, we found full coverage of carbonates on the particle surfaces, which likely result from decarboxylation of the MOFs and further stabilize the particles before decomposing to CO2, leaving an active surface rich with dangling bonds for catalytic turnover.Keywords: core−shell; Fischer−Tropsch synthesis; iron oxide@iron carbide nanoparticles; metal−organic frameworks; pyrolysis; weak interaction

Sulfur-doping achieves efficient oxygen reduction in pyrolyzed zeolitic imidazolate frameworks

Co-reporter:Chao Zhang, Bing An, Ling Yang, Binbin Wu, Wei Shi, Yu-Cheng Wang, La-Sheng Long, Cheng Wang and Wenbin Lin

Journal of Materials Chemistry A 2016 vol. 4(Issue 12) pp:4457-4463

Publication Date(Web):16 Feb 2016

DOI:10.1039/C6TA00768F

We report the first synthesis of sulfurated porous carbon materials with well-defined morphologies and uniform N/S distributions via pyrolysis of zeolitic imidazolate frameworks loaded with sulfur-containing molecules. The optimized sulfurated catalyst demonstrates excellent electrocatalytic activity for the oxygen reduction reaction (ORR) in both acid and alkaline media. The sulfurization process under optimized conditions can lower the ORR over-potential by ca. 170 mV at 3 mA cm−2, giving a non-precious metal catalyst with an onset ORR potential of 0.90 V (vs. RHE, similarly hereinafter)/half-wave potential of 0.78 V in 0.1 M HClO4 and an onset ORR potential of 0.98 V/half-wave potential of 0.88 V in 0.1 M KOH. Furthermore, the S-doped porous carbon materials perform better in the long-term durability test than the non-S-doped samples and standard commercially available Pt/C. We also discuss different sulfuration methods for the ZIF system, morphologies of pyrolyzed samples, and catalytically active sites.

Inside Back Cover: Self-Supporting MetalOrganic Layers as Single-Site Solid Catalysts (Angew. Chem. Int. Ed. 16/2016)

Co-reporter:Lingyun Cao;Zekai Lin;Fei Peng;Weiwei Wang;Ruiyun Huang; Cheng Wang; Jiawei Yan;Jie Liang; Zhiming Zhang;Teng Zhang; Lasheng Long; Junliang Sun; Wenbin Lin

Angewandte Chemie International Edition 2016 Volume 55( Issue 16) pp:

Publication Date(Web):

DOI:10.1002/anie.201602121

Self-Supporting MetalOrganic Layers as Single-Site Solid Catalysts

Co-reporter:Lingyun Cao;Zekai Lin;Fei Peng;Weiwei Wang;Ruiyun Huang; Cheng Wang; Jiawei Yan;Jie Liang; Zhiming Zhang;Teng Zhang; Lasheng Long; Junliang Sun; Wenbin Lin

Angewandte Chemie International Edition 2016 Volume 55( Issue 16) pp:4962-4966

Publication Date(Web):

DOI:10.1002/anie.201512054

Abstract

Metal–organic layers (MOLs) represent an emerging class of tunable and functionalizable two-dimensional materials. In this work, the scalable solvothermal synthesis of self-supporting MOLs composed of [Hf₆O₄(OH)₄(HCO₂)₆] secondary building units (SBUs) and benzene-1,3,5-tribenzoate (BTB) bridging ligands is reported. The MOL structures were directly imaged by TEM and AFM, and doped with 4′-(4-benzoate)-(2,2′,2′′-terpyridine)-5,5′′-dicarboxylate (TPY) before being coordinated with iron centers to afford highly active and reusable single-site solid catalysts for the hydrosilylation of terminal olefins. MOL-based heterogeneous catalysts are free from the diffusional constraints placed on all known porous solid catalysts, including metal–organic frameworks. This work uncovers an entirely new strategy for designing single-site solid catalysts and opens the door to a new class of two-dimensional coordination materials with molecular functionalities.

Self-Supporting MetalOrganic Layers as Single-Site Solid Catalysts

Co-reporter:Lingyun Cao;Zekai Lin;Fei Peng;Weiwei Wang;Ruiyun Huang; Cheng Wang; Jiawei Yan;Jie Liang; Zhiming Zhang;Teng Zhang; Lasheng Long; Junliang Sun; Wenbin Lin

Angewandte Chemie 2016 Volume 128( Issue 16) pp:5046-5050

Publication Date(Web):

DOI:10.1002/ange.201512054

Abstract

Metal–organic layers (MOLs) represent an emerging class of tunable and functionalizable two-dimensional materials. In this work, the scalable solvothermal synthesis of self-supporting MOLs composed of [Hf₆O₄(OH)₄(HCO₂)₆] secondary building units (SBUs) and benzene-1,3,5-tribenzoate (BTB) bridging ligands is reported. The MOL structures were directly imaged by TEM and AFM, and doped with 4′-(4-benzoate)-(2,2′,2′′-terpyridine)-5,5′′-dicarboxylate (TPY) before being coordinated with iron centers to afford highly active and reusable single-site solid catalysts for the hydrosilylation of terminal olefins. MOL-based heterogeneous catalysts are free from the diffusional constraints placed on all known porous solid catalysts, including metal–organic frameworks. This work uncovers an entirely new strategy for designing single-site solid catalysts and opens the door to a new class of two-dimensional coordination materials with molecular functionalities.

Innenrcktitelbild: Self-Supporting MetalOrganic Layers as Single-Site Solid Catalysts (Angew. Chem. 16/2016)

Co-reporter:Lingyun Cao;Zekai Lin;Fei Peng;Weiwei Wang;Ruiyun Huang; Cheng Wang; Jiawei Yan;Jie Liang; Zhiming Zhang;Teng Zhang; Lasheng Long; Junliang Sun; Wenbin Lin

Angewandte Chemie 2016 Volume 128( Issue 16) pp:

Publication Date(Web):

DOI:10.1002/ange.201602121

Highly Active Hydrogen Evolution Electrodes via Co-Deposition of Platinum and Polyoxometalates

Co-reporter:Chao Zhang, Yahui Hong, Ruihan Dai, Xinping Lin, La-Sheng Long, Cheng Wang, and Wenbin Lin

ACS Applied Materials & Interfaces 2015 Volume 7(Issue 21) pp:11648

Publication Date(Web):May 12, 2015

DOI:10.1021/acsami.5b02899

A highly active hydrogen evolution reaction (HER) electrode with low Pt loading on glassy carbon (GC) has been prepared by anodic platinum dissolution and co-deposition of polyoxometalates. TEM, EDS, XPS, CV, and ICP-MS analyses gave a Pt loading of 50–100 ng/cm2, corresponding to a Pt coverage of only 0.08–0.16 monolayer. With an overpotential of 65 mV at 20 mA/cm2, the modified GC has a HER activity comparable to that of the commercial Pt working electrode.Keywords: anodic platinum dissolution; hydrogen evolution reaction; polyoxometalate;

Pre-concentration and energy transfer enable the efficient luminescence sensing of transition metal ions by metal–organic frameworks

Co-reporter:Xinping Lin, Yahui Hong, Chao Zhang, Ruiyun Huang, Cheng Wang and Wenbin Lin

Chemical Communications 2015 vol. 51(Issue 95) pp:16996-16999

Publication Date(Web):30 Sep 2015

DOI:10.1039/C5CC06453H

The 2,2′-bipyridyl moieties lining the channels of two designer metal–organic frameworks (MOFs), UiO-bpydc and Eu-bpydc (bpydc is 2,2′-bipyridine 5,5′-dicarboxylic acid), recognize and pre-concentrate metal ion analytes and, in the case of Eu-bpydc, transfer energy to the Eu3+ centers, to provide highly sensitive luminescence sensors for transition metal ions.

Sulfur-doping achieves efficient oxygen reduction in pyrolyzed zeolitic imidazolate frameworks

Co-reporter:Chao Zhang, Bing An, Ling Yang, Binbin Wu, Wei Shi, Yu-Cheng Wang, La-Sheng Long, Cheng Wang and Wenbin Lin

Journal of Materials Chemistry A 2016 - vol. 4(Issue 12) pp:NaN4463-4463

Publication Date(Web):2016/02/16

DOI:10.1039/C6TA00768F

We report the first synthesis of sulfurated porous carbon materials with well-defined morphologies and uniform N/S distributions via pyrolysis of zeolitic imidazolate frameworks loaded with sulfur-containing molecules. The optimized sulfurated catalyst demonstrates excellent electrocatalytic activity for the oxygen reduction reaction (ORR) in both acid and alkaline media. The sulfurization process under optimized conditions can lower the ORR over-potential by ca. 170 mV at 3 mA cm−2, giving a non-precious metal catalyst with an onset ORR potential of 0.90 V (vs. RHE, similarly hereinafter)/half-wave potential of 0.78 V in 0.1 M HClO4 and an onset ORR potential of 0.98 V/half-wave potential of 0.88 V in 0.1 M KOH. Furthermore, the S-doped porous carbon materials perform better in the long-term durability test than the non-S-doped samples and standard commercially available Pt/C. We also discuss different sulfuration methods for the ZIF system, morphologies of pyrolyzed samples, and catalytically active sites.

Pre-concentration and energy transfer enable the efficient luminescence sensing of transition metal ions by metal–organic frameworks

Co-reporter:Xinping Lin, Yahui Hong, Chao Zhang, Ruiyun Huang, Cheng Wang and Wenbin Lin

Chemical Communications 2015 - vol. 51(Issue 95) pp:NaN16999-16999

Publication Date(Web):2015/09/30

DOI:10.1039/C5CC06453H

The 2,2′-bipyridyl moieties lining the channels of two designer metal–organic frameworks (MOFs), UiO-bpydc and Eu-bpydc (bpydc is 2,2′-bipyridine 5,5′-dicarboxylic acid), recognize and pre-concentrate metal ion analytes and, in the case of Eu-bpydc, transfer energy to the Eu3+ centers, to provide highly sensitive luminescence sensors for transition metal ions.