ACS Sustainable Chemistry & Engineering
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2019
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IF 6.97
Yuancai Ge,Hang Chu,Jiyi Chen,Peiyuan Zhuang,Qianyi Feng,William R. Smith,Pei Dong,Mingxin Ye,Jianfeng Shen
Constructing regularly catalytic arrays is essential for electrochemical catalysis, especially for hydrogen evolution reaction (HER). In this work, two-dimensional zeolitic imidazolate framework (ZIF) arrays were chosen as templates to construct few-layer MoS2-decorated hollow CoP. By coupling MoS2 nanosheets arrays and two-dimensional ZIF-67 derived CoP, the advantages of the active sites of MoS2 nanosheets edges and CoP are combined for efficient HER, which can drive a current density of 100 mA/cm2 in both acid (91 mV) and alkaline (135 mV) solutions for 10 h. Furthermore, the prepared catalyst can reach a current density of 10 mA/cm2 with overpotentials of only 53 and 77 mV in 0.5 M H2SO4 and 1 M KOH, respectively. Most importantly, we believe replacing ZIF-67 powders with 2D ZIF-67 arrays can boost the electrochemical activities for HER and this method can provide us a guideline for the future application of two-dimensional ZIF-67 arrays to construct efficient electrocatalysts.
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高影响因子
NANO
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2019
·
IF 1.293
Liang Yu,Qingfeng Yi,Xiaokun Yang,Xiulin Zhou
Development of a neutral Zn–air battery is of much significance due to the high stability of zinc in a neutral electrolyte. Here, Ni/Co-doped C–N nanotube composites (C–N, Ni/C–N, Co/C–N, and Ni–Co/C–N) as efficient oxygen reduction reaction (ORR) electrocatalysts in a neutral medium have been prepared by direct pyrolysis of Ni/Co salt, dicyandiamide (DCD) and glucose. Among the synthesized catalysts, Ni–Co/C–N presents a high ORR current density of 8.5 mA ⋅ cm − 2 in a 0.5 mol ⋅ L − 1 KNO 3 solution. The ORR electron transfer number of the catalyst Ni–Co/C–N is 3.8, indicating that O 2 is almost completely reduced to H 2 O. A neutral zinc–air battery utilizing a 0.5 mol ⋅ L − 1 KNO 3 solution has been assembled by using the prepared composite catalyst coated on carbon paper as an air cathode, and Zn plate as an anode. The battery with the cathode catalyst Ni–Co/C–N delivers the open-circuit voltage of 1.13 V and the maximum power density of 65 mW ⋅ cm − 2 . The constant discharge current density of 50 mA ⋅ cm − 2 , 100 mA ⋅ cm − 2 and 150 mA ⋅ cm − 2 can last 202 h, 93 h and 11 h, respectively. A stable voltage plateau appears at various discharge current densities. The neutral zinc–air battery can be repeatedly discharged after replacing the zinc anode. Results indicate that the synthesized Ni–Co/C–N catalyst is an excellent cathode material applied to a neutral zinc–air battery, showing broad application prospects as a mobile power source.
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高影响因子
JOURNAL OF CATALYSIS
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2019
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IF 7.723
Zuohui Wang,Nannan Heng,Xiaobing Wang,Jinling He,Yong Zhao
The original active site units and morphologies structure on catalyst surface is highly important to promote the rate of chemical reaction, while less concern is paid on their dynamic change during reaction process. Understanding these reconstructions in reactions is essential to illustrate the correlations between the structure and reactivity of catalyst, as well as the rational design of efficient catalyst. Here, single metal phophide materials are adopted as model electrocatalysts to show the structure evolution in the process of oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). After both OER and HER operation, the core-shell structured metal-hydroxide/oxyhydroxide@metal-phosphide catalysts are generated, resulting in the high but decreased activity. To overcome the activity deterioration of metal phosphide induced by morphology reconstruction, binary heterostructure metal phosphides catalysts are designed and show the better OER and HER activity and stability compared to those of single phosphides. The work illustrates the structure-performance relationship of catalyst surface dynamics on catalytic performance, which will provide the guidance for designing high performance electrocatalysts, photocatalysts, and thermal catalysts.
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高影响因子
Nanomaterials
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2019
·Vol. 9
·期 8
·1135
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IF 4.034
Yinglin Zhang,Yulin Shi,Bo Yan,Tingting Wei,Yin Lv,Long Chen,Feng Yu,Xuhong Guo
The rational treatment of hazardous textile sludge is critical and challenging for the environment and a sustainable future. Here, a water-soluble chitosan derivative was synthesized and used as an effective flocculant in removal of reactive dye from aqueous solution. Employing these chitosan-containing textile sludges as precursors, graphene-like carbon nanosheets were synthesized through simple one-step carbonization with the use of Fe (III) salt as graphitization catalyst. It was found that the resultant graphene-like carbon nanosheets material at thickness near 3.2 nm (NSC-Fe-2) showed a high graphitization degree, high specific surface area, and excellent bifunctional electrochemical performance. As-prepared NSC-Fe-2 catalyst exhibited excellent oxygen reduction reaction (ORR) activity (onset potential 1.05 V) and a much better methanol tolerance than that of commercial Pt/C (onset potential 0.98 V) in an alkaline medium. Additionally, as electrode materials for supercapacitors, NSC-Fe-2 also displayed an outstanding specific capacitance of 195 F g−1at 1 A g−1and superior cycling stability (loss of 3.4% after 2500 cycles). The good electrochemical properties of the as-prepared NSC-Fe materials could be attributed to the ultrathin graphene-like nanosheets structure and synergistic effects from codoping of iron and nitrogen. This work develops a simple but effective strategy for direct conversion of textile sewage sludge to value-added graphene-like carbon, which is considered as a promising alternative to fulfill the requirements of environment and energy.Keywords:chitosan;textile sludge;graphene-like carbon nanosheets;oxygen reduction reaction;supercapacitor
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PubMed
高影响因子
Molecular Catalysis
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2018
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IF 0
Zhongzhe Wei,Xuefeng Li,Jiang Deng,Jing Wang,Haoran Li,Yong Wang
The catalytic transformation from levulinic acid (LA) into γ-valerolactone (GVL) is of great interest as it is an impressive strategy to convert lignocellulosic platform chemical into high value-added compounds. Herein, a novel heterogeneous catalyst made of Ru nanoparticles (NPs) supported on N-doped hierarchically porous carbon from biomass, Ru/NHPC, was shown to be highly active, selective and stable in this transformation. The reaction can proceed smoothly under mild conditions in aqueous media even at room temperature. The catalyst Ru/NHPC could be recycled for 13 consecutive runs exhibiting no obvious activity decay, much better than that of Ru NPs supported on activated carbon. The process offers an efficient, environmentally responsible, and safe approach to high production of GVL.
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ACS Sustainable Chemistry & Engineering
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2018
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IF 6.14
Yanli Niu,Xiaoqin Huang,Lei Zhao,Weihua Hu,Chang Ming Li
We herein report a facile strategy to synthesize transition metal/spinel oxide nanoparticles coupled with nitrogen-doped graphene (Co/CoFe2O4@N-graphene) as an efficient bifunctional electrocatalyst toward the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). This approach involves a spontaneous solution-polymerization of polydopamine (PDA) film on graphene oxide (GO) sheets in the presence of Fe3+ and Co2+ to form the Fe/Co-PDA-GO precursor, followed by pyrolysis at 800 °C in argon (Ar) atmosphere. During the calcination process, Co/CoFe2O4 nanoparticles are in situ formed via high-temperature solid state reaction and are further entrapped by the PDA-derived N-doped carbon layer. As-prepared Co/CoFe2O4@N-graphene exhibits highly efficient catalytic activity and excellent stability for both ORR and OER in alkaline solution. This work reports a facile synthetic approach to develop highly active electrocatalysts while offering great flexibility to tailor their components and morphologies and thus provides a useful route to the design and synthesis of a broad variety of electrocatalysts.
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高影响因子
CARBON
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2018
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IF 7.082
Guang Li,Qingfeng Yi,Xiaokun Yang,Yao Chen,Xiulin Zhou,Gang Xie
Ni-Co-N doped honeycomb carbon (HC) nano-composites Ni 3 Co 1 -N/HC (Ni 3 Co 1 -N/HC-20, Ni 3 Co 1 -N/HC-30 and Ni 3 Co 1 -N/HC-40 with respective metal mass percentage of 20%, 30% and 40%) with a regular hexagonal structure have been fabricated by using the simple polymethylmethacrylate (PMMA) emulsion template method . The side length of the carbon hexagon is ca. 100 nm for the honeycomb carbon (HC). For the Ni 3 Co 1 -N/HC catalysts, the NiCo nanoparticles and the nanocarbon tubes derived from dicyandiamide are uniformly dispersed on HCs. The as-synthesized Ni 3 Co 1 -N/HC catalysts exhibit efficient electroactivity for oxygen reduction reaction (ORR) in alkaline medium and possess excellent tolerance to the alcohols (ethanol, n -propanol and iso -propanol). Based on these results, a membrane-less direct alcohol fuel cell has been assembled with the Ni 3 Co 1 -N/HC as the cathodic catalyst, the ternary Pd 7 Ag 2 Sn 2 /CNT as the anodic catalyst and alcohol (ethanol, n -propanol or iso -propanol) as the fuel. The fuel cell with the Ni 3 Co 1 -N/HC-40 as the cathodic catalyst displays the open circuit voltage of 0.79 V and maximum power density of 42.2 mW cm −2 for the ethanol fuel , 0.60 V and 33.3 mW cm −2 for the n -propanol fuel, and 0.43 V and 14.4 mW cm −2 for the iso -propanol fuel. The membrane-less fuel cell also presents stable discharge performance at different discharging current densities.
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高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2018
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IF 4.229
Ruijing Wang,Peng Sun,Huanwen Wang,Xuefeng Wang
Development of highly-active and noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) is of critical challenge for water splitting, and optimizing the structure and the composition of the relative materials is very necessary to obtain the high-quality catalysts. Herein, a novel molybdenum carbide/N-doped carbon (Mo 2 C/NC) hybrid is fabricated by using the hierarchical polyaniline tube network as a carbon source and a reactive template, and the as-fabricated Mo 2 C/NC hybrid possesses a uniform hierarchical tube structure. The coupling of the ultrafine Mo 2 C nanoparticles and the N-doped carbon substrate provides the abundant active sites and accelerates the charge transfer process. The final Mo 2 C/NC catalyst gives the excellent catalytic activity for HER in alkaline condition, which shows a lower overpotential of 142 mV at 10 mA cm −2 and a small Tafel slope of 61 mV decade −1 in 1 M KOH.
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高影响因子
Inorganic Chemistry Frontiers
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2018
·Vol. 5
·期 9
·2211-2217
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IF 5.106
Xianghong Li,Xu Sun,Xiang Ren,Dan Wu,Xuan Kuang,Hongmin Ma,Tao Yan,Qin Wei
Electrochemical oxygen reduction is a key process for many energy storage and conversion devices, and finding highly efficient, economical, and durable electrocatalysts to replace the Pt-based catalyst for the oxygen reduction reaction (ORR) is a critical obstacle. In this article, porous Fe–N-codoped materials are obtained by pyrolysis of a defined precursor of polydopamine-coated Fe3O4 as not only template but also nitrogen and iron source. In 0.1 M KOH, the as-prepared catalyst exhibited high ORR activity (onset potential of 0.949 V and half-wave potential of 0.836 V vs. RHE), with excellent electrochemical stability, durability and remarkable tolerance toward methanol. The successful synthesis of porous nanospheres provides a novel way to explore a series of mesoporous metal electrocatalysts for energy conversion.
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高影响因子
Nanoscale
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2018
·Vol. 10
·期 32
·15238-15248
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IF 7.233
Qijun Che,Ningning Bai,Qing Li,Xinhong Chen,Ya Tan,Xi Xu
An enormous challenge in the development of renewable hydrogen sources for electricity-driven water-splitting systems has been the limitation of the earth-abundant and robust highly-active cathode electrocatalysts. In this work, we developed a simple sulfur-anion doping strategy to obtain the S-doped NiCo composite (S-NiCo@50) on Ni foam (NF) via a one-step electrochemical deposition. It was found that doped sulfur plays a crucial role in reducing the overpotential of hydrogen evolution by providing abundant active sites as identified by the XPS spectrum. The formed metallic Ni and Co effectively promoted electron transportation. The synergistic effects between the amorphous CoxNiyS(x+y) substance and crystalline Ni and Co metal seemed to result in enhanced HER activity. In particular, the S-NiCo@50 electrode, featuring a hierarchical morphology, showed an ultralow overpotential of 28 and 125 mV at 10 and 100 mA cm−2, respectively, in 1.0 M NaOH with a large exchange current density (j0) of 4.8 mA cm−2 as well as high conductivity and stability; its catalytic properties are superior to most of the reported alkaline electrocatalysts and are on par with commercial Pt/C. Assembled with the counter electrode (Ni–Fe/NF), the overall water splitting was proved with a low 1.55 V at 10 mA cm−2. Moreover, we built the Ni24Co6S6 cluster as the S-NiCo@50 model and revealed its intrinsic activity by density functional theory (DFT) calculations. This study shows that S-doping and component control can be an exquisite strategy for realizing high-efficiency electrochemical water reduction.
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高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2018
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IF 4.229
Mengchen Wu,Xianxiang Hu,Congling Li,Jian Li,Haijun Zhou,Xia Zhang,Rui Liu
High-performance non-precious metal-doped carbon catalysts for oxygen reduction reactions (ORR) are viable candidates in lieu of platinum-based catalysts. It has been universally reported that active Co–N sites combined with Fe–N sites embedded in carbon matrix represent the most promising active sites for ORR process. Benefiting from the cage-encapsulated-precursor pyrolysis strategy, herein, we fabricated a Fe–N and Co–N homogeneously doped carbon framework by one step. TEM demonstrated the ultimate product had well-defined morphology with Fe (0.54 at%), Co (0.31 at%) and N (2.94 at%) uniformly distributed into the carbon skeleton. The N 2 absorption-desorption isotherms indicated the MOF-derived catalyst had a high specific surface area of 647.6 m 2 g −1 and inherit hierarchical porosity . Significantly, such FeCo–NC catalyst outperformed a current density (5.6 mA cm −2 ) at 0.70 V (vs reversible hydrogen electrode) 1.18 times higher than that of a commercial 20 wt% Pt/C (5 mA cm −2 ) catalyst in alkaline medium , and more positive peak potential of 0.63 V than its counterparts. Its high cycling stability and immunity towards methanol crossover in a wide range pH value showed good potential to be used as cathodes in proton exchange membrane fuel cells (PEMFCs) for long term operation. This simple synthesis strategy would to some degree leverage a cage-encapsulated-precursor for tailored utility of active sites for ORR in a porous carbon framework.
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高影响因子
APPLIED SURFACE SCIENCE
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2018
·
IF 4.439
Keke Xu,Xiuli Fu,Hong Li,Zhijian Peng
Enhancing the electrocatalytic activity of transition metal phosphides (TMPs) for hydrogen evolution has become an attractive way for noble-metal-free electrocatalysts. In this work, a novel composite of network-like tungsten phosphide nanostructures on carbon fibers (CFs@WP) was prepared by a two-step high-temperature calcination strategy. Owing to the high electrochemical active surface area originating from the WP nanostructures of network-like morphology and the enhanced conductivity caused by the introduction of carbon fibers, the obtained CFs@WP composite, as an integrated hydrogen evolution cathode, exhibits much higher electrocatalytic activity for hydrogen evolution than pure WP nano-/micro-particles after toasting their corresponding suspension onto bare CFs. This catalyst could, in 0.5 mol·L −1 H 2 SO 4 , deliver a current density of 10 and 100 mA·cm −2 respectively at the over-potential of merely 137 mV and 215 mV, and present a small Tafel slope of 69 mV·dec −1 as well as excellent stability at various current densities, although it may exhibit relatively inferior catalytic activity in hydrogen evolution in neutral and alkaline conditions. The present strategy may also offer a straight-forward model to enhance the hydrogen evolution activity of other TMPs catalysts.
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高影响因子
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