共查询到20条相似文献,搜索用时 31 毫秒
1.
Rahul Majee Arun Kumar Dr. Tisita Das Dr. Sudip Chakraborty Prof. Dr. Sayan Bhattacharyya 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(7):2903-2911
Five-fold intertwined AgxNi1−x (x=0.01–0.25) heterogeneous alloy nanocrystal (NC) catalysts, prepared through unique reagent combinations, are presented. With only ca. 5 at % Ag (AgNi-5), Pt-like activity has been achieved at pH 14. To reach a current density of 10 mA cm−2 the extremely stable AgNi-5 requires an overpotential of 24.0±1.2 mV as compared to 20.1±0.8 mV for 20 % Pt/C, both with equal catalyst loading of 1.32 mg cm−2. The turnover frequency (TOF) is as high as 2.1 H2 s−1 at 50 mV (vs. RHE). Site-specific elemental analyses show the Ag:Ni compositional variation, where the apex and edges of the decahedra are Ag-rich, thereby exposing Ni onto the faces to achieve maximum charge transport for an exceptional pH universal HER activity. DFT calculations elucidate the relative H-atom adsorption capability of the Ni centers as a function of their proximity to Ag atom. 相似文献
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Yanmin Hu Tingting Chao Yapeng Li Peigen Liu Tonghui Zhao Ge Yu Cai Chen Xiao Liang Huile Jin Shuwen Niu Wei Chen Dingsheng Wang Yadong Li 《Angewandte Chemie (International ed. in English)》2023,62(35):e202308800
Water electrolysis for H2 production is restricted by the sluggish oxygen evolution reaction (OER). Using the thermodynamically more favorable hydrazine oxidation reaction (HzOR) to replace OER has attracted ever-growing attention. Herein, we report a twisted NiCoP nanowire array immobilized with Ru single atoms (Ru1−NiCoP) as superior bifunctional electrocatalyst toward both HzOR and hydrogen evolution reaction (HER), realizing an ultralow working potential of −60 mV and overpotential of 32 mV for a current density of 10 mA cm−2, respectively. Inspiringly, two-electrode electrolyzer based on overall hydrazine splitting (OHzS) demonstrates outstanding activity with a record-high current density of 522 mA cm−2 at cell voltage of 0.3 V. DFT calculations elucidate the cooperative Ni(Co)−Ru−P sites in Ru1−NiCoP optimize H* adsorption, and enhance adsorption of *N2H2 to significantly lower the energy barrier for hydrazine dehydrogenation. Moreover, a self-powered H2 production system utilizing OHzS device driven by direct hydrazine fuel cell (DHzFC) achieve a satisfactory rate of 24.0 mol h−1 m−2. 相似文献
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Dr. Yang Wang Dr. Xiaopeng Li Dr. Zhong Huang Dr. Haozhi Wang Dr. Zelin Chen Dr. Jinfeng Zhang Prof. Xuerong Zheng Prof. Yida Deng Prof. Wenbin Hu 《Angewandte Chemie (International ed. in English)》2023,62(6):e202215256
It is vitally important to develop highly active, robust and low-cost transition metal-based electrocatalysts for overall water splitting in neutral solution especially at large current density. In this work, amorphous Mo-doped NiS0.5Se0.5 nanosheets@crystalline NiS0.5Se0.5 nanorods (Am−Mo−NiS0.5Se0.5) was synthesized using a facil one-step strategy. In phosphate buffer saline solution, the Am−Mo−NiS0.5Se0.5 shows tiny overpotentials of 48 and 209 mV for hydrogen evolution reaction (HER), 238 and 514 mV for oxygen evolution reaction (OER) at 10 and 1000 mA cm−2, respectively. Moreover, Am−Mo−NiS0.5Se0.5 delivers excellent stability for at least 300 h without obvious degradation. Theoretical calculations revealed that the Ni sites in the defect-rich amorphous structure of Am−Mo−NiS0.5Se0.5 owns higher electron state density and strengthened the binding energy of H2O, which will optimize H adsorption/desorption energy barriers and reduce the adsorption energy of OER determining step. 相似文献
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PaulA. Liddell Gerdenis Kodis Linda delaGarza JeffreyL. Bahr AnaL. Moore ThomasA. Moore Devens Gust 《Helvetica chimica acta》2001,84(9):2765-2783
The two molecular triads 1a and 1b consisting of a porphyrin (P) covalently linked to a fullerene (C60) electron acceptor and tetrathiafulvalene (TTF) electron‐donor moiety were synthesized, and their photochemical properties were determined by transient absorption and emission techniques. Excitation of the free‐base‐porphyrin moiety of the TTF−P2 H−C60 triad 1a in tetrahydro‐2‐methylfuran solution yields the porphyrin first excited singlet state TTF−1P2 H−C60, which undergoes photoinduced electron transfer with a time constant of 25 ps to give TTF−P2 H.+−C60.−. This intermediate charge‐separated state has a lifetime of 230 ps, decaying mainly by a charge‐shift reaction to yield a final state, TTF.+−P2 H−C60.−. The final state has a lifetime of 660 ns, is formed with an overall yield of 92%, and preserves ca. 1.0 eV of the 1.9 eV inherent in the porphyrin excited state. Similar behavior is observed for the zinc analog 1b . The TTF‐PZn.+−C60.− state is formed by ultrafast electron transfer from the porphyrinatozinc excited singlet state with a time constant of 1.5 ps. The final TTF.+−PZn−C60.− state is generated with a yield of 16%, and also has a lifetime of 660 ns. Although charge recombination to yield a triplet has been observed in related donor‐acceptor systems, the TTF.+−P−C60.− states recombine to the ground state, because the molecule lacks low‐energy triplet states. This structural feature leads to a longer lifetime for the final charge‐separated state, during which the stored energy could be harvested for solar‐energy conversion or molecular optoelectronic applications. 相似文献
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Somayeh Norouziyanlakvan Dr. Gyandshwar Kumar Rao Dr. Jeffrey Ovens Dr. Bulat Gabidullin Dr. Darrin Richeson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(54):13518-13522
Water is the most sustainable source for H2 production, and the efficient electrocatalytic production of H2 from mixed water/acetonitrile solutions by using two new air-stable nickel(II) pincer complexes, [Ni(κ3-2,6-{Ph2PNR}2(NC5H3)Br2] (R=H I , Me II ) is reported. Hydrogen generation from H2O/CH3CN solutions is initiated at −2 V against Fc+/0, and bulk electrocatalysis studies showed that the catalyst functions with an excellent Faradaic efficiency and a turnover frequency of 160 s−1. A DFT computational investigation of the reduction behavior of I and II revealed a correlation of H2 formation with charge donation from electrons originating in a reduced ligand-localized orbital. As a result, these catalysts are proposed to proceed by a novel mechanism involving electron/proton transfer between a Ni0I species bonded to an anionic PN3P ligand (“L−/Ni0I”) and a NiI-hydride (“Ni−H”). Furthermore, these catalysts are able to reduce phenol and acetic acid, more active proton sources, at lower potentials that correlate with the substrate pKa. 相似文献
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Dr. Bowen He Dr. Peng Xiao Dr. Sijie Wan Dr. Jianjun Zhang Prof. Tao Chen Prof. Liuyang Zhang Prof. Jiaguo Yu 《Angewandte Chemie (International ed. in English)》2023,62(50):e202313172
Cooperative coupling of H2 evolution with oxidative organic synthesis is promising in avoiding the use of sacrificial agents and producing hydrogen energy with value-added chemicals simultaneously. Nonetheless, the photocatalytic activity is obstructed by sluggish electron-hole separation and limited redox potentials. Herein, Ni-doped Zn0.2Cd0.8S quantum dots are chosen after screening by DFT simulation to couple with TiO2 microspheres, forming a step-scheme heterojunction. The Ni-doped configuration tunes the highly active S site for augmented H2 evolution, and the interfacial Ni−O bonds provide fast channels at the atomic level to lower the energy barrier for charge transfer. Also, DFT calculations reveal an enhanced built-in electric field in the heterojunction for superior charge migration and separation. Kinetic analysis by femtosecond transient absorption spectra demonstrates that expedited charge migration with electrons first transfer to Ni2+ and then to S sites. Therefore, the designed catalyst delivers drastically elevated H2 yield (4.55 mmol g−1 h−1) and N-benzylidenebenzylamine production rate (3.35 mmol g−1 h−1). This work provides atomic-scale insights into the coordinated modulation of active sites and built-in electric fields in step-scheme heterojunction for ameliorative photocatalytic performance. 相似文献
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Nickel nanoparticle and graphene interfaces of various stoichiometries were created through electrodeposition techniques. The catalytic behavior of the electrodeposited films was investigated through spectro-electrochemical methodologies. UV-vis absorbance spectra of the electrodeposited films are significantly different in the air and alkaline medium. Furthermore, UV-vis and Raman spectroscopy confirmed the coupling of Ni nanoparticles (Ni-NP) with the graphene framework, along with NiO and Ni(OH)2. A combination of Raman and impedance spectroscopy revealed that the surface adsorption and charge transfer properties of the electrodeposited films are entirely dependent on the defects on graphene structure as well as distribution of Ni-NP on graphene. The electrodeposited films possess heterogeneous catalytic properties with a low overpotential of 50 mV (10 mA/cm−2) for hydrogen evolution reaction, as well as 601 mV and 391 mV (at 50 mA/cm−2) for the oxygen evolution reaction and urea oxidation reaction, respectively. In addition, eelectrodeposited samples show extraordinary overall water splitting performance by achieving a current density of 10 mA/cm2 at a very low applied potential of 1.38 V. This synergistic coupling of Ni and graphene renders the electrodeposited samples promising candidates as electrodes for overall water splitting in alkaline and urea-supplemented solutions. 相似文献
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Shengpeng Mo Xinya Zhao Shuangde Li Lili Huang Xin Zhao Quanming Ren Mingyuan Zhang Ruosi Peng Yanan Zhang Xiaobin Zhou Yinming Fan Prof. Qinglin Xie Prof. Yanbing Guo Prof. Daiqi Ye Prof. Yunfa Chen 《Angewandte Chemie (International ed. in English)》2023,62(50):e202313868
Solar-to-chemical energy conversion under weak solar irradiation is generally difficult to meet the heat demand of CO2 reduction. Herein, a new concentrated solar-driven photothermal system coupling a dual-metal single-atom catalyst (DSAC) with adjacent Ni−N4 and Fe−N4 pair sites is designed for boosting gas-solid CO2 reduction with H2O under simulated solar irradiation, even under ambient sunlight. As expected, the (Ni, Fe)−N−C DSAC exhibits a superior photothermal catalytic performance for CO2 reduction to CO (86.16 μmol g−1 h−1), CH4 (135.35 μmol g−1 h−1) and CH3OH (59.81 μmol g−1 h−1), which are equivalent to 1.70-fold, 1.27-fold and 1.23-fold higher than those of the Fe−N−C catalyst, respectively. Based on theoretical simulations, the Fermi level and d-band center of Fe atom is efficiently regulated in non-interacting Ni and Fe dual-atom pair sites with electronic interaction through electron orbital hybridization on (Ni, Fe)−N−C DSAC. Crucially, the distance between adjacent Ni and Fe atoms of the Ni−N−N−Fe configuration means that the additional Ni atom as a new active site contributes to the main *COOH and *HCO3 dissociation to optimize the corresponding energy barriers in the reaction process, leading to specific dual reaction pathways (COOH and HCO3 pathways) for solar-driven photothermal CO2 reduction to initial CO production. 相似文献
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Feini Hao Chao Yang Ximeng Lv Fangshuai Chen Prof. Shengyao Wang Prof. Gengfeng Zheng Prof. Qing Han 《Angewandte Chemie (International ed. in English)》2023,62(50):e202315456
Herein, the exposure of highly-active nitrogen cation sites has been accomplished by photo-driven quasi-topological transformation of a 1,10-phenanthroline-5,6-dione-based covalent organic framework (COF), which contributes to hydrogen peroxide (H2O2) synthesis during the 2-electron O2 photoreduction. The exposed nitrogen cation sites with photo-enhanced Lewis acidity not only act as the electron-transfer motor to adjust the inherent charge distribution, powering continuous and stable charge separation, and broadening visible-light adsorption, but also providing a large number of active sites for O2 adsorption. The optimal catalyst shows a high H2O2 production rate of 11965 μmol g−1 h−1 under visible light irradiation and a remarkable apparent quantum yield of 12.9 % at 400 nm, better than most of the previously reported COF photocatalysts. This work provides new insights for designing photo-switchable nitrogen cation sites as catalytic centers toward efficient solar to chemical energy conversion. 相似文献
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Kailian Zhang Lei Tian Jingfei Yang Fengxiu Wu Prof. Leigang Wang Prof. Hua Tang Prof. Zhao-Qing Liu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2024,136(5):e202317816
Breaking the trade-off between activity and selectivity has perennially been a formidable endeavor in the field of hydrogen peroxide (H2O2) photosynthesis, especially the side-on configuration of oxygen (O2) on the catalyst surface will cause the cleavage of O−O bonds, which drastically hinders the H2O2 production performance. Herein, we present an atomically heteroatom P doped ZnIn2S4 catalyst with tunable oxygen adsorption configuration to accelerate the ORR kinetics essential for solar-driven H2O2 production. Indeed, the spectroscopy characterizations (such as EXAFS and in situ FTIR) and DFT calculations reveal that heteroatom P doped ZnIn2S4 at substitutional and interstitial sites, which not only optimizes the coordination environment of Zn active sites, but also facilitates electron transfer to the Zn sites and improves charge density, avoiding the breakage of O−O bonds and reducing the energy barriers to H2O2 production. As a result, the oxygen adsorption configuration is regulated from side-on (Yeager-type) to end-on (Pauling-type), resulting in the accelerated ORR kinetics from 874.94 to 2107.66 μmol g−1 h−1. This finding offers a new avenue toward strategic tailoring oxygen adsorption configuration by the rational design of doped photocatalyst. 相似文献
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Jing Zhang Yufeng Zhao Wanting Zhao Jing Wang Yongfeng Hu Chengyu Huang Xingli Zou Yang Liu Dengsong Zhang Xionggang Lu Hongjin Fan Yanglong Hou 《Angewandte Chemie (International ed. in English)》2023,62(52):e202314303
Transition metal single atom electrocatalysts (SACs) with metal-nitrogen-carbon (M−N−C) configuration show great potential in oxygen evolution reaction (OER), whereby the spin-dependent electrons must be allowed to transfer along reactants (OH−/H2O, singlet spin state) and products (O2, triplet spin state). Therefore, it is imperative to modulate the spin configuration in M−N−C to enhance the spin-sensitive OER energetics, which however remains a significant challenge. Herein, we report a local field distortion induced intermediate to low spin transition by introducing a main-group element (Mg) into the Fe−N−C architecture, and decode the underlying origin of the enhanced OER activity. We unveil that, the large ionic radii mismatch between Mg2+ and Fe2+ can cause a FeN4 in-plane square local field deformation, which triggers a favorable spin transition of Fe2+ from intermediate (dxy2dxz2dyz1dz21, 2.96 μB) to low spin (dxy2dxz2dyz2, 0.95 μB), and consequently regulate the thermodyna-mics of the elementary step with desired Gibbs free energies. The as-obtained Mg/Fe dual-site catalyst demonstrates a superior OER activity with an overpotential of 224 mV at 10 mA cm−2 and an electrolysis voltage of only 1.542 V at 10 mA cm−2 in the overall water splitting, which outperforms those of the state-of-the-art transition metal SACs. 相似文献
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Yu Wang Bochun Liang Jiaxiong Zhu Geng Li Qing Li Ruquan Ye Jun Fan Chunyi Zhi 《Angewandte Chemie (International ed. in English)》2023,62(23):e202302583
Constructing a reliable solid-electrolyte interphase (SEI) is imperative for enabling highly reversible zinc metal (Zn0) electrodes. Contrary to conventional “bulk solvation” mechanism, we found the SEI structure is dominated by electric double layer (EDL) adsorption. We manipulate the EDL adsorption and Zn2+ solvation with ether additives (i.e. 15-crown-5, 12-crown-4, and triglyme). The 12-crown-4 with medium adsorption on EDL leads to a layer-structured SEI with inner inorganic ZnFx/ZnSx and outer organic C−O−C components. This structure endows SEI with high rigidness and strong toughness enabling the 100 cm2 Zn||Zn pouch cell to exhibit a cumulative capacity of 4250 mAh cm−2 at areal-capacity of 10 mAh cm−2. More importantly, a 2.3 Ah Zn||Zn0.25V2O5⋅n H2O pouch cell delivers a recorded energy density of 104 Wh Lcell−1 and runs for >70 days under the harsh conditions of low negative/positive electrode ratio (2.2 : 1), lean electrolyte (8 g Ah−1), and high-areal-capacity (≈13 mAh cm−2). 相似文献
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Abhishikta Chatterjee Dr. Papri Mondal Priyanka Chakraborty Bidyapati Kumar Sourav Mandal Prof. Corrado Rizzoli Dr. Rajat Saha Prof. Bibhutosh Adhikary Prof. Subrata K. Dey 《Angewandte Chemie (International ed. in English)》2023,62(42):e202307832
In this research, highly efficient heterogeneous bifunctional (BF) electrocatalysts (ECs) have been strategically designed by Fe coordination (CR) complexes, [Fe2L2(H2O)2Cl2] (C1) and [Fe2L2(H2O)2(SO4)].2(CH4O) (C2) where the high seven CR number synergistically modifies the electronic environment of the Fe centre for facilitation of H2O electrolysis. The electronic status of Fe and its adjacent atomic sites have been further modified by the replacement of −Cl− in C1 by −SO42− in C2 . Interestingly, compared to C1 , the O−S−O bridged C2 reveals superior BF activity with extremely low overpotential (η) at 10 mA cm−2 (140 mVOER, 62 mVHER) and small Tafel slope (120.9 mV dec−1OER, 45.8 mV dec−1HER). Additionally, C2 also facilitates a high-performance alkaline H2O electrolyzer with cell voltage of 1.54 V at 10 mA cm−2 and exhibits remarkable long-term stability. Thus, exploration of the intrinsic properties of metal–organic framework (MOF)-based ECs opens up a new approach to the rational design of a wide range of molecular catalysts. 相似文献
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《Electroanalysis》2017,29(2):387-391
Electrodeposition of functional metal surfaces has received great attention because of their useful applications. Recently, interesting electrodeposition behavior of Pt at −0.8 V (vs. Ag/AgCl) was reported, where underpotential deposited H (Hupd) layers played a unique role in the electrodeposition. Here, we report the effect of anionic electrolytes and precursor concentrations on the electrochemical deposition behavior of Pt. Depending on these two experimental parameters, two distinct Pt structures, monolayer Pt films and Pt spheres, were electrodeposited at −0.8 V. In addition to the underpotential deposited H (Hupd) layers formed at −0.8 V, the adsorption of Cl− also plays a significant role in determining the electrodeposited Pt structures. When the PtCl42− concentration was low and the Cl− concentration was high enough for the adsorption of PtCl42− to be blocked by the Hupd and Cl− layers, monolayer Pt films were electrodeposited. Otherwise, further electrodeposition of Pt spheres over the monolayer Pt films occurred. The effect of other halide ion adsorption and the controlled growth of Pt spheres during the Pt electrodeposition were also investigated. The electrochemical deposition behavior of Pt demonstrated in this work provides insight into the fabrication of functional Pt surfaces. 相似文献
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Wenxing Zou Markus Bursch Kristian L. Mears Cary R. Stennett Ping Yu James C. Fettinger Stefan Grimme Philip P. Power 《Angewandte Chemie (International ed. in English)》2023,62(22):e202301919
Reaction of {LiC6H2−2,4,6-Cyp3⋅Et2O}2 (Cyp=cyclopentyl) ( 1 ) of the new dispersion energy donor (DED) ligand, 2,4,6-triscyclopentylphenyl with SnCl2 afforded a mixture of the distannene {Sn(C6H2−2,4,6-Cyp3)2}2 ( 2 ), and the cyclotristannane {Sn(C6H2−2,4,6-Cyp3)2}3 ( 3 ). 2 is favored in solution at higher temperature (345 K or above) whereas 3 is preferred near 298 K. Van't Hoff analysis revealed the 3 to 2 conversion has a ΔH=33.36 kcal mol−1 and ΔS=0.102 kcal mol−1 K−1, which gives a ΔG300 K=+2.86 kcal mol−1, showing that the conversion of 3 to 2 is an endergonic process. Computational studies show that DED stabilization in 3 is −28.5 kcal mol−1 per {Sn(C6H2−2,4,6-Cyp3)2 unit, which exceeds the DED energy in 2 of −16.3 kcal mol−1 per unit. The data clearly show that dispersion interactions are the main arbiter of the 3 to 2 equilibrium. Both 2 and 3 possess large dispersion stabilization energies which suppress monomer dissociation (supported by EDA results). 相似文献
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Dr. Abdalaziz Aljabour Houssein Awada Dr. Luyang Song Dr. He Sun Simon Offenthaler Farzaneh Yari Dr. Matthias Bechmann Prof. Dr. Markus Clark Scharber Prof. Dr. Wolfgang Schöfberger 《Angewandte Chemie (International ed. in English)》2023,62(21):e202302208
As alternative energy sources are essential to reach a climate-neutral economy, hydrogen peroxide (H2O2) as futuristic energy carrier gains enormous awareness. However, seeking for stable and electrochemically selective H2O2 ORR electrocatalyst is yet a challenge, making the design of—ideally—bifunctional catalysts extremely important and outmost of interest. In this study, we explore the application of a trimetallic cobalt(II) triazole pyridine bis-[cobalt(III) corrole] complex CoIITP[CoIIIC]2 3 in OER and ORR catalysis due to its remarkable physicochemical properties, fast charge transfer kinetics, electrochemical reversibility, and durability. With nearly 100 % selective catalytic activity towards the two-electron transfer generated H2O2, an ORR onset potential of 0.8 V vs RHE and a cycling stability of 50 000 cycles are detected. Similarly, promising results are obtained when applied in OER catalysis. A relatively low overpotential at 10 mA cm−2 of 412 mV, Faraday efficiency 98 % for oxygen, an outstanding Tafel slope of 64 mV dec−1 combined with superior stability. 相似文献
20.
Dr. Lijuan Zhang Hanfeng Zhou Prof. Xiaoju Yang Dr. Shengbo Zhang Prof. Haimin Zhang Xuan Yang Prof. Xintai Su Prof. Jiangwei Zhang Prof. Zhang Lin 《Angewandte Chemie (International ed. in English)》2023,62(13):e202217473
Atomically dispersed metal catalysts show potential advantages in N2 reduction reaction (NRR) due to their excellent activity and efficient metal utilization. Unfortunately, the reported catalysts usually exhibit unsatisfactory NRR activity due to their poor N2 adsorption and activation. Herein, we report a novel Sn atomically dispersed protuberance (ADP) by coordination with substrate C and O to induce positive charge accumulation on Sn site for improving its N2 adsorption, activation and NRR performance. The extended X-ray absorption fine structure (EXAFS) spectra confirmed the local coordination structure of the Sn ADPs. NRR activity was significantly promoted via Sn ADPs, exhibiting a remarkable NH3 yield (RNH3) of 28.3 μg h−1 mgcat−1 (7447 μg h−1 mgSn−1) at −0.3 V. Furthermore, the enhanced N2Hx intermediates was verified by in situ experiments, yielding consistent results with DFT calculation. This work opens a new avenue to regulate the activity and selectivity of N2 fixation. 相似文献