JOURNAL OF POWER SOURCES
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2017
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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
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能源材料
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催化化学
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储能技术
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材料科学
✓ 已验证
DOI
高影响因子
Small
·
2019
·Vol. 15
·期 10
·1804546
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IF 10.856
Jing Yang,Donghua Guo,Shulin Zhao,Yue Lin,Rui Yang,Dongdong Xu,Naien Shi,Xiaoshu Zhang,Lingzhi Lu,Ya-Qian Lan,Jianchun Bao,Min Han
As one class of important functional materials, transition metal phosphides (TMPs) nanostructures show promising applications in catalysis and energy storage fields. Although great progress has been achieved, phase-controlled synthesis of cobalt phosphides nanocrystals or related nanohybrids remains a challenge, and their use in overall water splitting (OWS) is not systematically studied. Herein, three kinds of cobalt phosphides nanocrystals encapsulated by P-doped carbon (PC) and married with P-doped graphene (PG) nanohybrids, including CoP@PC/PG, CoP-Co 2 P@PC/PG, and Co 2 P@PC/PG, are obtained through controllable thermal conversion of presynthesized supramolecular gels that contain cobalt salt, phytic acid, and graphene oxides at proper temperature under Ar/H 2 atmosphere. Among them, the mixed-phase CoP-Co 2 P@PC/PG nanohybrids manifest high electrocatalytic activity toward both hydrogen and oxygen evolution in alkaline media. Remarkably, using them as bifunctional catalysts, the fabricated CoP-Co 2 P@PC/PG || CoP-Co 2 P@PC/PG electrolyzer only needs a cell voltage of 1.567 V for driving OWS to reach the current density at 10 mA cm −2 , superior to their pure-phase counterparts and recently reported bifunctional catalysts based devices. Also, such a CoP-Co 2 P@PC/PG || CoP-Co 2 P@PC/PG device exhibits outstanding stability for OWS. This work may shed some light on optimizing TMPs nanostructures based on phase engineering, and promote their applications in OWS or other renewable energy options.
研究领域:
材料科学
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电催化
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能源化学
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纳米材料
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可再生能源
✓ 已验证
DOI
高影响因子
Nano Energy
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2020
·
IF 16.602
Qingyan Zhou,Zhen Zhang,Jiajun Cai,Bing Liu,Yunlong Zhang,Xiaofei Gong,Xulei Sui,Aiping Yu,Lei Zhao,Zhenbo Wang,Zhongwei Chen
Rational design and construction of highly efficient and durable non-noble-metal bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is crucial to promote the widespread implementation of rechargeable Zn-air batteries. Herein, a bifunctional catalyst comprising Co nanoparticles uniformly embedded in hollow nitrogen doped carbon tubes (Co@hNCTs) is fabricated by a facile tube-directed templating strategy. In this strategy, surfactant-treated polypyrrole (PPy) nanotubes serve as the structure-guiding templates for efficient capture of Co 2+ , realizing the in-situ growth of zeolitic imidazolate frameworks-67 (ZIF-67) nanocrystals on PPy nanotubes . Sodium laurylsulfonate acts as anionic surfactant to endow PPy nanotubes with functional electronegative surface and strong anchoring effect toward ZIF-67, playing the pivotal role in binding of ZIF-67 nanocrystals with PPy nanotubes potently. Consequently, the developed catalyst presents a superior ORR activity with the half-wave potential of 0.87 V excellent durability with only a 7 mV loss of half-wave potential after 5000 cycles. The catalyst also exhibits superior catalytic performance for OER. When serving as an air electrode in Zn-air batteries, a large power density of 149 mW cm −2 and long-term cyclability for over 500 h are realized in ambient air, implying the great potential in practical application.
研究领域:
材料科学
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电化学
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能源存储
·
催化化学
·
纳米材料
✓ 已验证
DOI
高影响因子
Journal of Energy Chemistry
·
2019
·
IF 5.162
Bo Lv,Sha Zeng,Wei Yang,Jian Qiao,Chao Zhang,Chengfeng Zhu,Minghai Chen,Jiangtao Di,Qingwen Li
Recently, the development of high-performance bifunctional oxygen catalysts integrated with flexible conductive scaffolds for rechargeable metal-air batteries has attracted considerable interest, driving by fast-growing wearable electronics . Herein, we report a flexible bifunctional oxygen catalyst thin film consisting of Co–N–C bifunctional catalysts embedding in carbon nanotube (CNT) networks. The catalyst is readily prepared by pyrolysis of cobalt-based zeolitic imidazolate frameworks (ZIF-67) that are in-situ synthesized in CNT networks. Such catalyst film demonstrates very high catalytic activities for oxygen reduction (onset potential: 0.91 V, and half-wave potential: 0.87 V vs. RHE) and oxygen evolution (10 mA cm −2 at 1.58 V) reactions, high methanol tolerance property, and long-term stability (97% current retention). Moreover, our integrated catalyst film shows very good structure flexibility and robustness. Based on the obtained film air electrodes, flexible Zn–air batteries demonstrate low charging and discharging overpotentials (0.82 V at 1 mA cm −1 ) and excellent structure stability in the bending tests . These results indicate that presently reported catalyst films are potential air electrodes for flexible metal–air batteries.
研究领域:
材料科学
·
电化学
·
纳米能源
·
先进功能材料
·
可再生能源
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）