JOURNAL OF POWER SOURCES
·
2017
·
IF 6.395
H.R. Jiang,W. Shyy,M.C. Wu,L. Wei,T.S. Zhao
The potential of B 4 C as a metal-free catalyst for vanadium redox reactions is investigated by first-principles calculations. Results show that the central carbon atom of B 4 C can act as a highly active reaction site for redox reactions , due primarily to the abundant unpaired electrons around it. The catalytic effect is then verified experimentally by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests, both of which demonstrate that B 4 C nanoparticles can enhance the kinetics for both V 2+ /V 3+ and VO 2+ /VO 2 + redox reactions, indicating a bi-functional effect. The B 4 C-nanoparticle-modified graphite felt electrodes are finally prepared and tested in vanadium redox flow batteries (VRFBs). It is shown that the batteries with the prepared electrodes exhibit energy efficiencies of 88.9% and 80.0% at the current densities of 80 and 160 mA cm −2 , which are 16.6% and 18.8% higher than those with the original graphite felt electrodes. With a further increase in current densities to 240 and 320 mA cm −2 , the batteries can still maintain energy efficiencies of 72.0% and 63.8%, respectively. All these results show that the B 4 C-nanoparticle-modified graphite felt electrode outperforms existing metal-free catalyst modified electrodes , and thus can be promising electrodes for VRFBs.
研究领域:
电化学
·
能源材料
·
催化化学
·
储能技术
·
材料科学
✓ 已验证
DOI
高影响因子
FUEL
·
2021
·
IF 6.609
Hongsheng Yu,Suhang Chen,Xiaodong Yu,Wei Zhang,Christian Paravan,Luigi T. DeLuca,Ruiqi Shen
The slow regression rate induced by the difficulty of pyrolysis has limited the practical application of hydroxyl-terminated polybutadiene (HTPB)-based fuels for hybrid rocket propulsion. A possible strategy is the use of suitable transition metal elements promoting polymer matrix thermal decomposition of fuels. This paper investigates the effects of nickel acetylacetonate, Ni(acac) 2 , on the thermal stability and combustion of HTPB-based fuel formulations. The presented experimental results show that the addition of Ni(acac) 2 can intensely decrease the thermal stability of HTPB thus enhancing the solid fuel regression rate even at a small additive mass fraction: under an oxygen mass flux of 50 kg/m 2 s, HTPB + 5 wt% Ni(acac) 2 shows a 25.5% increase over the non-loaded baseline. Kinetics analyses reveal that the catalytic effect is mainly induced by the Ni 2+ in Ni(acac) 2 at the early stage of decomposition, and by the NiO produced from the oxidative decomposition of Ni(acac) 2 in the fuel final degradation stage. On the other hand, the addition of Ni(acac) 2 decreases the combustion heat of HTPB-based fuels significantly and implies the accumulation of its decomposition products (much metal Ni, moderate elemental C, and a little NiO.) at the fuel regressing surface. Eventually, when the content of Ni(acac) 2 exceeds 5 wt%, the growth of regression rate slows down rapidly, and a performance detriment occurs at 40 wt%. This study verifies the catalytic effect of Ni(acac) 2 on polymer matrix for HTPB based fuels showing the attractive regression rate performance of this additive.
研究领域:
推进剂化学
·
燃烧学
·
高分子材料科学
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航天动力工程
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催化化学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 16
·9450-9458
·
IF 3.361
Rui Zhang,Zheng Wang,Lin Zhu,Weixin Lv,Wei Wang
For the electrochemical reduction of oxygen the development of heteroatom-doped carbon-based transition metal catalysts has become a recognized strategy to replace traditional noble metal catalysts. In this work a catalyst consisting of CoFe nanoparticles encapsulated in N-doped carbon-based materials (NC) supported by carbon nanotubes (CNTs), i.e. Fe3Co1@NC/CNTs, was modified via treatment with a phosphate salt to synthesize a P-Fe3Co1@NC/CNTs catalyst. The P-Fe3Co1@NC/CNTs exhibits with 5.29 mA cm−2 an enhanced current density which is comparable to a Pt/C catalyst. In addition, a stability and methanol resistance better than the Pt/C catalyst were observed which is ascribed to the carbon encapsulation and the synergies between the two transition metals. Finally, the reaction mechanism of P-doping was studied and discussed. These results provide possible directions for carbon-based catalysts and doping with heteroatoms for the improvement of catalytic activity. Moreover, the zinc–air battery assembled with P-Fe3Co1@NC/CNTs as the air-cathode exhibited a high-power density of 73 mW cm−2, which is comparable to that of Pt/C (71 mW cm−2) and a specific capacity of 763 mA h g−1. The prepared catalyst could potentially serve to take the place of precious metal catalysts in rechargeable Zn–air batteries.
研究领域:
电催化
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材料化学
·
能源化学
·
纳米材料
·
电化学能源存储
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燃料电池
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金属-空气电池
✓ 已验证
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
·
2021
·Vol. 42
·期 10
·1798-1807
·
IF 8.271
Xiangyong Zhang,Tianying Liu,Ting Guo,Xueying Han,Zongyun Mu,Qiang Chen,Jiangmin Jiang,Jing Yan,Jiaren Yuan,Dezhi Wang,Zhuangzhi Wu,Zongkui Kou
Controllably mounting foreign atoms on the surfaces of earth-abundant electrocatalysts strongly improve their surface electronic properties for optimizing the catalytic performance of surficial sites to an unusual level, and provides a good platform to gain deep insights into catalytic reactions . The present work describes, employing ultrafine W 2 C nanoislands (average size: 2.3 nm) monodispersed on the N, P dual-doped carbon frameworks as a model system, how to regulate the atomic phosphorous-mounting effect on the surfaces of W 2 C to derive an active and stable P-mounting W 2 C (WCP) catalyst for both acidic and alkaline hydrogen evolution reaction (HER). Since in situ phosphorus substitution into carbon sites of preformed W 2 C nanoislands gradually proceeds from surfaces to solids, so that using a proper amount of phosphorus sources can readily control the surface mounting level to avoid the mass P-doping into the bulk. By this way, the activity per active site of WCP catalyst with robust stability can be optimized to 0.07 and 0.56 H 2 s −1 at –200 mV overpotential in acid and base, respectively, which reach up to the several-fold of pure-phase W 2 C (0.01 and 0.05 H 2 s −1 ). Theoretical investigations suggest that compared with solid P doping, the P mounting on W 2 C surface can more remarkably enhance its metallicity and decrease the hydrogen release barrier. This finding disclosed a key correlation between surface foreign atom-mounting and catalytic activity , and suggested a logical extension to other earth-abundant catalysts for various catalytic reactions .
研究领域:
材料化学
·
电催化
·
纳米材料
·
能源科学
·
表面科学
·
理论计算
✓ 已验证
DOI
高影响因子
RSC Advances
·
2017
·Vol. 7
·期 72
·45420-45431
·
IF 3.108
Jiuli Guo,Huanhuan Yu,Feng Dong,Baolin Zhu,Weiping Huang,Shoumin Zhang
A highly efficient and stable Au–Cu/hydroxyapatite (HAP, Ca10(PO4)6(OH)2) catalyst was reported. HAP was prepared through a deposition–precipitation method. Au–Cu/HAP catalysts were obtained by a two-step impregnation approach. The samples were characterized by XRD, TEM, SEM, UV-Vis, ICP, XPS, H2-TPR, and O2-TPD. CO oxidation reaction was carried out to evaluate the catalytic performance of samples. TEM and UV-Vis results showed that the metallic particles supported on Au–Cu/HAP were smaller than those on Au/HAP, and they were highly dispersed on the HAP support. Patterns of XPS revealed that CuO nanoparticles were formed in the Cu/HAP catalyst, while CuO and Cu2O species coexisted in Au–Cu/HAP catalyst. Based on the O2-TPD data, the addition of copper to Au/HAP gave rise to more new O2 adsorption sites and bigger O2 adsorption capacity. The catalysis results indicated that the Au–Cu/HAP was capable of obtaining higher efficiency and stability compared with Au/HAP and Cu/HAP for CO oxidation. It was likely that the synergistic interaction between gold and CuOx phase created the most active sites on Au–Cu/HAP and was responsible for the enhanced activity and stability in comparison with Au/HAP and Cu/HAP.
研究领域:
催化化学
·
材料科学
·
环境化学
·
纳米催化
·
表面科学
✓ 已验证
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2018
·
IF 6.759
Xiaolong Liu,Qingzhen Han,Wenbo Shi,Cheng Zhang,Erwei Li,Tingyu Zhu
In this work, ruthenium-based bimetallic catalysts of 1Ru-5 M/TiO 2 (M = Co, Ce, Fe, Mn, Cu, Ni) were prepared and evaluated in ethyl acetate oxidation. It was found that 1Ru-5Cu/TiO 2 gave the highest catalytic activity. The influence of CuO content and the preparation method on the catalytic activity was also studied. 1Ru-5Cu/TiO 2 showed great catalytic stability in the on-stream reaction test. The influence of H 2 O on the catalytic activity is presented. The bimetallic catalyst 1Ru-5Cu/TiO 2 showed better catalytic performance than the monometallic catalysts 1Ru/TiO 2 and 5Cu/TiO 2 . XRD, TEM, HAADF-STEM, H 2 -TPR, and XPS characterizations were conducted, and the synergistic effect between Ru and Cu was well presented. In situ FTIR studies were also conducted, and the reaction intermediates were revealed on the catalyst surface. The theoretical calculations suggested that ethyl acetate is more easily adsorbed on the CuO surface, while it reacts more easily on the RuO 2 surface . Accordingly, a reaction mechanism for the catalytic oxidation of ethyl acetate over a Ru-Cu bimetallic catalyst is proposed.
研究领域:
催化化学
·
环境化学
·
表面科学
·
材料化学
·
物理化学
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2017
·
IF 3.387
Xiong Wang,Zhenyou Li,Xiaoyu Han,Zhengang Han,Yongxiao Bai
Porous organic Polymers (POPs) can not only exhibit high specific surface area and pore volume, but also tunable pore size distribution. Herein, copolymers of 2-hydroxyethylmethylacrylate (HEMA) and divinylbenzene (DVB) with specific pore structure were synthesized via a dispersion polymerization strategy, and then immobilized metallocene catalysts with well-defined pore structure were obtained on the produced POP supports. The nitrogen sorption and Gel permeation chromatography (GPC) results demonstrate that the pore structure of the immobilized metallocene catalyst is highly dependent on the pore structure of the POPs , and the pore structure of metallocene catalysts or the POPs has a significant influence on the molecular chain growth of the produced polyethylene. By tuning the distribution of the active species scattered in the micro- and the narrow meso-pore range (roughly ≤4 nm), the chain growth of the polyolefin can be tailored effectively during the polymerization process, although differential scanning calorimetry (DSC) and temperature rising elution fractionation (TREF) results show that the chemical composition distributions (CCDs) of produced PE from the POPs-supported metallocene catalysts are not determined by polymerization activity or molecule chain length, but mainly by the active site species scattered in the supported catalysts. Scanning electron micrograph (SEM) shows that the produced polyethylene has highly porous fabric which consists of nanofiber and spherical beads of micron dimension.
研究领域:
高分子化学
·
催化化学
·
材料科学
·
纳米材料
·
聚合物科学
·
石油化工
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2019
·
IF 6.361
Kai-Wen Cao,Hao Huang,Fu-Min Li,Hong-Chang Yao,Juan Bai,Pei Chen,Pu-Jun Jin,Zi-Wei Deng,Jing-Hui Zeng,Yu Chen
The reactive and stable catalysts for the oxygen reduction reaction are highly desirable for low temperature fuel cells. The commercial oxygen reduction reaction electrocatalysts generally reply on noble metal based nanomaterials, which suffer from inherent cost and selectivity issues. At present, it still remains challenge for designing efficient non-noble metal-based oxygen reduction reaction electrocatalysts. Herein, we successfully synthesize Co nanoparticles supported on three-dimensionally N-doped holey graphene aerogels hybrids by the high-temperature calcination of the graphene aerogels-polyallylamine-Co II hybrids. The component optimized hybrids show the excellent electrocatalytic activity for oxygen reduction reaction in alkaline media, which is comparable to commercial Pt/C electrocatalyst. Meanwhile, the hybrids also show eminent tolerance for CO and methanol, attributing to their excellent oxygen reduction reaction selectivity. The three-dimensionally interconnected structure of graphene aerogels, N-doping, uniform dispersion and high crystallinity of Co nanoparticles, and holey structure of graphene contribute to the striking oxygen reduction reaction activity of hybrids.
研究领域:
材料科学
·
电化学
·
纳米催化
·
能源材料
·
燃料电池
✓ 已验证
DOI
高影响因子
CATALYSIS TODAY
·
2018
·
IF 4.667
Xintong Zhou,Chang-jun Liu
Structured porous carbon materials have been extensively applied for catalyst, sensor, adsorbent, energy storage materials and many others. However, the preparation of such carbon materials in a controllable way remains a significant challenge. In this work, 3D printing has been employed to prepare porous carbon structures with tailorable pore sizes. A starch/gelatin ink has been applied as carbon source with SiO 2 monodispersed spheres as hard template. The process exhibits an excellent printing accuracy. Controllable meso and macro structures can be thereby obtained. The printed monolithic structures have been used as metal-free catalysts for the selective oxidation of benzyl alcohol, as an illustration. The monolithic and meso/macro-porous structure has a remarkable influence on the reaction rate. A high conversion with high benzaldehyde selectivity has been achieved. The 3D printing strategy provides us a simple, low cost and reliable way of fabricating carbon structures with designable meso/macro-pores, which is promising for many other applications beyond catalysis.
研究领域:
材料科学
·
催化化学
·
能源材料
·
纳米结构材料
·
功能材料
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2022
·Vol. 47
·期 33
·14916-14929
·
IF 7.139
Hongzhi Wang,Chunxiao Wang,Weiguo Zhang,Suwei Yao
Developing non-noble metal catalysts with excellent electrocatalytic performance and stability is of great significance to hydrogen production by water electrolysis, but there are still problems of low activity, complex preparation and high cost. Herein, we fabricated a novel Ni 3 S 2 /Ni(OH) 2 dual-functional electrocatalyst by a one-step fast electrodeposition on nickel foam (NF). While maintaining the electrocatalytic performance of Ni 3 S 2 , the existence of heterostructure and Ni(OH) 2 co-catalyst function greatly improves the overall water splitting performance of Ni 3 S 2 /Ni(OH) 2 –NF. Hence, It shows a low overpotential of 66 mV at 10 mA cm −2 for HER and 249 mV at 20 mA cm −2 for OER. The dual-functional electrocatalyst needs only 1.58 V at 20 mA cm −2 when assembled two-electrode electrolytic cell. Impressively, the electrocatalyst also shows outstanding catalytic stability for about 800 h when 20 and 50 mA cm −2 constant current was applied, respectively which demonstrates a potential electrocatalyst for overall water splitting.
研究领域:
材料科学
·
电化学
·
能源催化
·
纳米材料
·
可持续能源
·
功能材料
·
界面化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）