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2D catalyst

Jan Philip Kraack, Angelo Frei, Roger Alberto, Peter Hamm
We investigate the ultrafast vibrational dynamics of monolayers from adsorbed Rhenium-carbonyl CO2-reduction catalysts on a semiconductor surface (Indium-Tin-Oxide (ITO)) with ultrafast 2D ATR IR spectroscopy. The complexes are partially equipped with isotope-labelled (13C) carbonyl ligands to generate two spectroscopically distinguishable forms of the molecules. Ultrafast vibrational energy transfer between the molecules is observed via the temporal evolution of cross-peaks between their symmetric carbonyl stretching vibrations...
May 18, 2017: Journal of Physical Chemistry Letters
Li Zhao, Biliang Dong, Shaozhou Li, Lijun Zhou, Linfei Lai, Zhiwei Wang, Shulin Zhao, Min Han, Kai Gao, Min Lu, Xiaoji Xie, Bo Chen, Zhengdong Liu, Xiangjing Wang, Hao Zhang, Hai Li, Juqing Liu, Hua Zhang, Xiao Huang, Wei Huang
Two-dimensional (2D) metal-organic framework (MOF) nanosheets have been recently regarded as the model electrocatalysts due to their porous structure, fast mass and ion transfer through the thickness, and large portion of exposed active metal centers. Combining them with electrically conductive 2D nanosheets is anticipated to achieve further improved performance in electrocatalysis. In this work, we in-situ hybridized 2D cobalt 1,4-benzenedicarboxylate (CoBDC) with Ti3C2Tx (the MXene phase) nanosheets via an inter-diffusion reaction-assisted process...
May 17, 2017: ACS Nano
Yuchi Fan, Shintaro Ida, Aleksandar Staykov, Taner Akbay, Hidehisa Hagiwara, Junko Matsuda, Kenji Kaneko, Tatsumi Ishihara
Obtaining bifunctional electrocatalysts with high activity for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is a main hurdle in the application of rechargeable metal-air batteries. Earth-abundant 3d transition metal-based catalysts have been developed for the OER and ORR; however, most of these are based on oxides, whose insulating nature strongly restricts their catalytic performance. This study describes a metallic Ni-Fe nitride/nitrogen-doped graphene hybrid in which 2D Ni-Fe nitride nanoplates are strongly coupled with the graphene support...
May 16, 2017: Small
Jose Fernando Godinez-Salomon, Ruben Mendoza-Cruz, Maria Josefina Arellano-Jiménez, Miguel José-Yacamán, Christopher P Rhodes
Electrochemical oxygen reduction reaction (ORR) catalysts that have both high activities and long-term stabilities are needed for proton-exchange membrane fuel cells (PEMFCs) and metal-air batteries. Two-dimensional (2D) materials based on graphene have shown high catalytic activities, however carbon-based materials result in significant catalyst degradation due to carbon oxidation that occurs at high electrochemical potentials. Here, we introduce the synthesis and electrochemical performance of metallic 2D nanoframes which represent a new approach to translate 2D materials into unsupported (carbon-free) electrocatalysts that have both significantly higher ORR catalytic activity and stability compared with conventional Pt/carbon electrocatalysts...
May 12, 2017: ACS Applied Materials & Interfaces
Yongwei Wu, Benzhao He, Changyun Quan, Chao Zheng, Haiqin Deng, Rongrong Hu, Zujin Zhao, Fei Huang, Anjun Qin, Ben Zhong Tang
The metal-free click polymerization (MFCP) of activated alkynes and azides or activated azide and alkynes have been developed into powerful techniques for the construction of polytriazoles without the obsession of metallic catalyst residues problem. However, the MFCP of activated azides and alkynes is rarely applied in preparation of functional polytriazoles. In this paper, soluble multifunctional polytriazoles (PIa and PIb) with high weight-average molecular weights (Mw up to 32 000) are prepared via the developed metal-free poly-cycloaddition of activated azide and alkynes in high yields (up to 90%)...
May 11, 2017: Macromolecular Rapid Communications
Feng Yan, Qi Li, Dan Xu, Xu Ou
Heteroatom-doped carbon materials have been considered as substitutes of Pt-based electrocatalysts for oxygen reduction reaction (ORR) in alkaline fuel cells. Here, we reported the synthesis of oxygen-containing nitrogen-doped carbon (ONC) nanosheets via the carbonization of a mixture containing glucose and dicyandiamide (DCDA). In situ formed graphitic carbon nitride (g-C3N4) derived from DCDA provides a nitrogen-rich template, facilitating the formation of ONC nanosheets. The resultant ONC materials with high nitrogen contents, high specific surface areas, and mesoporous total volume displayed the excellent electrochemical performances, including a similar ORR onset potential, half-potential, a higher diffusion-limited current and excellent tolerance to methanol than that of the commercial Pt/C catalyst, respectively...
May 11, 2017: Chemistry, An Asian Journal
Yuxi Han, Sutao Zhang, Jianghua He, Yuetao Zhang
A metal-free B(C6F5)3-catalyzed approach is developed for the disproportionation reaction of a series of indoles with various hydrosilanes, without any additives such as base and production of any small molecule such as dihydrogen. This boron catalyst system also exhibits excellent catalytic performance for practical application, such as catalyst loading as low as 0.01 mol % under solvent-free conditions, and a long-life catalytic performance highlighted by a constant catalytic activity being maintained and excellent yields being achieved for the desired products over 10 sequential additions of starting materials...
May 18, 2017: Journal of the American Chemical Society
Peng Teng, Ning Ma, Darrell Cole Cerrato, Fengyu She, Timothy Odom, Xing Wang, Li-June Ming, Arjan van der Vaart, Lukasz Wojtas, Hai Xu, Jianfeng Cai
New types of foldamer scaffolds are formidably challenging to design and synthesize yet highly desirable as structural mimics of peptides/proteins with a wide repertoire of functions. In particular, the development of peptidomimetic helical foldamers holds promise for new biomaterials, catalysts and drug molecules. Unnatural L-sulfono-γ-AApeptides were recently developed and shown to have potential applications in both biomedical and material sciences. However, D-sulfono-γ-AApeptides, the enantiomers of L-sulfono-γ-AApeptides, have never been studied due to the lack of high resolution three-dimensional structures to guide structure-based design...
May 8, 2017: Journal of the American Chemical Society
Dandan Wu, Ming Wen, Chen Gu, Qingsheng Wu
An economical catalyst with excellent selectivity and high activity is eagerly desirable for H2 generation from the decomposition of N2H4·H2O. Here, a bifunctional two-dimensional NiFe/CeO2 nanocatalyst with NiFe nanoparticles (∼5 nm) uniformly anchored on CeO2 nanosheets supports has been successfully synthesized through a dynamic controlling coprecipitation process followed by in-situ topotactic reduction. Even without NaOH as catalyst promoter, as-designed Ni0.6Fe0.4/CeO2 nanocatalyst can show high activity for selectively catalyzing H2 generation (reaction rate (molN2H4 mol(-1)NiFe h(-1)): 5...
May 5, 2017: ACS Applied Materials & Interfaces
Xu-Sheng Du, Chun-Yu Wang, Qiong Jia, Rong Deng, Hua-Sheng Tian, Hou-Yu Zhang, Kamel Meguellati, Ying-Wei Yang
We report a quantitative synthetic strategy of a [1]rotaxane from a representative pseudo[1]rotaxane. The structure of the [1]rotaxane was characterized by (1)H NMR, (13)C NMR, 2D NMR, mass spectroscopy, and melting point, and its optimized geometry in CHCl3 by theoretical calculation at the B3LYP/6-31G(D) level using the PCM model matched well with 2D NOESY. This [1]rotaxane proves to be a good catalyst for the Knoevenagel reaction in CHCl3, which follows second order kinetics.
May 9, 2017: Chemical Communications: Chem Comm
Xiang Chen, Huanlin Chen, Jian Guan, Jieming Zhen, Zijun Sun, Pingwu Du, Yalin Lu, Shangfeng Yang
Graphitic carbon nitride (g-C3N4) as an emerging two-dimensional (2D) nanomaterial has been commonly used as a metal-free photocatalyst with potential applications in visible light photocatalytic water-splitting. However, the photocatalytic activity of g-C3N4 is quite low due to its relatively large band gap and the existence of contact resistance between the nanosheets. Herein we report for the first time the facile synthesis of a covalently bonded g-C3N4/C60 hybrid via a solid-state mechanochemical route and its application in photocatalytic hydrogen production under visible light...
May 4, 2017: Nanoscale
Xiaochen Shen, Yanbo Pan, Bin Liu, Jinlong Yang, Jie Zeng, Zhenmeng Peng
The reaction mechanism and properties of a catalytic process are primarily determined by the interactions between reacting species and catalysts. However, the interactions are often challenging to be experimentally measured, especially for unstable intermediates. Therefore, it is of significant importance to establish an exact relationship between chemical-catalyst interactions and catalyst parameters, which will allow calculation of these interactions and thus advance their mechanistic understanding. Herein we report the description of adsorption energy on transition metals by considering both ionic bonding and covalent bonding contributions and introduce the work function as one additional responsible parameter...
April 19, 2017: Physical Chemistry Chemical Physics: PCCP
Guangwei Geng, Penglei Chen, Bo Guan, Lang Jiang, Zhongfei Xu, Dawei Di, Zeyi Tu, Weichang Hao, Yuanping Yi, Chuncheng Chen, Minghua Liu, Wenping Hu
Metal-free catalytic materials have recently received broad attention as promising alternatives to metal-involved catalysts. This is owing to their inherent capability to overcome the inevitable limitations of metal-involved catalysts, such as high sensitivity to poisoning, the limited reserves, high cost and scarcity of metals (especially noble metals), etc. However, the lack of shape-controlled metal-free catalysts with well-defined facets is a formidable bottleneck limiting our understandings on the underlying structure-activity relationship at atomic/molecular level, which thereby restrains their rational design...
April 19, 2017: ACS Nano
Xiao-Yuan Liu, Hao Chen, Ruili Wang, Yuequn Shang, Qiong Zhang, Wei Li, Guozhen Zhang, Juan Su, Cao Thang Dinh, F Pelayo García de Arquer, Jie Li, Jun Jiang, Qixi Mi, Rui Si, Xiaopeng Li, Yuhan Sun, Yi-Tao Long, He Tian, Edward H Sargent, Zhijun Ning
Hydrogen generation via photocatalysis-driven water splitting provides a convenient approach to turn solar energy into chemical fuel. The development of photocatalysis system that can effectively harvest visible light for hydrogen generation is an essential task in order to utilize this technology. Herein, a kind of cadmium free Zn-Ag-In-S (ZAIS) colloidal quantum dots (CQDs) that shows remarkably photocatalytic efficiency in the visible region is developed. More importantly, a nanocomposite based on the combination of 0D ZAIS CQDs and 2D MoS2 nanosheet is developed...
April 11, 2017: Advanced Materials
Chao Huang, Xiao Han, ZhiChao Shao, Kuan Gao, Mengjia Liu, Yanjie Wang, Jie Wu, Hongwei Hou, Liwei Mi
A series of solvent-induced Ag-based coordination polymers (CPs) (1-3), which were synthesized by regulating the size, shape, and polarity of solvent molecules (EtOH, iPrOH, 1,4-dioxane) as structure-directing agents, has been used as heterogeneous catalysts to explore how the metal-metal bonds could serve as cooperative catalysis for tandem acylation-Nazarov cyclization reaction to prepare cyclopentenone[b]pyrroles frameworks. Structural conversions from a three-dimensional (3D) framework of 1 to the structure of 2 with Ag-Ag-Ag bonds and to the two-dimensional (2D) framework of 3 with Ag-Ag bonds, arising from the different sizes, shapes, and polarities of the solvent molecules, were observed...
April 7, 2017: Inorganic Chemistry
Kenta Homma, Tsukuru Masuda, Aya Mizutani Akimoto, Kenichi Nagase, Kazuyoshi Itoga, Teruo Okano, Ryo Yoshida
The propagation control of chemical waves via a pentagonal patterned structure in a self-oscillating polymer brush composed of N-isopropylacrylamide and a metal catalyst for the Belousov-Zhabotinsky (BZ) reaction is reported. The patterned self-oscillating polymer brush is prepared by combining surface-initiated atom transfer radical polymerization and maskless photolithography. Surface modification is confirmed by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, 3D measuring laser microscopy, and fluorescence microscopy...
April 6, 2017: Small
Wancheng Zhao, Xingxing Tan, Jingyun Jiang, Feijie Liu, Tiancheng Mu
β-cyclodextrin-assisted aqueous-exfoliation method is successfully introduced to prepare transition metal dichalcogenides nanosheets (TMDs), which is cheap, high-efficiency, scalable, and environmentally friendly. As the cases, MoS2 and ReS2 nanoflakes are prepared using our method. Particularly, the effective exfoliation of ReS2 crystal in aqueous environment is demonstrated for the first time. Moreover, exfoliated nanomaterials can be availably utilized in hydrogen evolution reaction (HER) as noble-metal-free catalyst...
April 3, 2017: Chemistry, An Asian Journal
Andrey B Lysenko, Ganna A Senchyk, Konstantin V Domasevitch, Merten Kobalz, Harald Krautscheid, Jakub Cichos, Miroslaw Karbowiak, Patrícia Neves, Anabela A Valente, Isabel S Gonçalves
Three organic ligands bearing 1,2,4-triazolyl donor moieties, (S)-4-(1-phenylpropyl)-1,2,4-triazole (trethbz), 4-(1,2,4-triazol-4-yl)benzoic acid (trPhCO2H), and 3-(1H-imidazol-4-yl)-2-(1,2,4-triazol-4-yl)propionic acid (trhis), were prepared to evaluate their coordination behavior in the development of molybdenum(VI) oxide organic hybrids. Four compounds, [Mo2O6(trethbz)2]·H2O (1), [Mo4O12(trPhCO2H)2]·0.5H2O (2a), [Mo4O12(trPhCO2H)2]·H2O (2b), and [Mo8O25(trhis)2(trhisH)2]·2H2O (3), were synthesized and characterized...
April 3, 2017: Inorganic Chemistry
Michio Matsumoto, Raghunath R Dasari, Woojung Ji, Cameron H Feriante, Timothy C Parker, Seth R Marder, William R Dichtel
Imine-linked two-dimensional covalent organic frameworks (2D COFs) are crystalline polymer networks with enhanced stability and broader monomer scope compared to boronate ester-linked systems. They are traditionally prepared by condensing polyfunctional aldehydes and amines at elevated temperature in a mixture of organic solvents and aqueous CH3CO2H, which catalyzes imine formation and exchange. Under these conditions, an amorphous imine-linked polymer network precipitates quickly and then crystallizes after extended reaction times (hours to days)...
March 27, 2017: Journal of the American Chemical Society
Chenbao Lu, Diana Tranca, Jian Zhang, Fermı N Rodrı Guez Hernández, Yuezeng Su, Xiaodong Zhuang, Fan Zhang, Gotthard Seifert, Xinliang Feng
Molybdenum carbide (Mo2C) based catalysts were found to be one of the most promising electrocatalysts for hydrogen evolution reaction (HER) in acid media in comparison with Pt-based catalysts but were seldom investigated in alkaline media, probably due to the limited active sites, poor conductivity, and high energy barrier for water dissociation. In this work, Mo2C-embedded nitrogen-doped porous carbon nanosheets (Mo2C@2D-NPCs) were successfully achieved with the help of a convenient interfacial strategy. As a HER electrocatalyst in alkaline solution, Mo2C@2D-NPC exhibited an extremely low onset potential of ∼0 mV and a current density of 10 mA cm(-2) at an overpotential of ∼45 mV, which is much lower than the values of most reported HER electrocatalysts and comparable to the noble metal catalyst Pt...
April 25, 2017: ACS Nano
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