APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Jiaming Wang,Guilong Liu,Huixian Zhong,Pengfei Song,Kang An,Ziyang Zhang,Ang Cao,Yuan Liu
In this work, Co δ+ -Co 2 C decorated-Co-Ni alloy nanoparticles (NPs) loaded on Mg-Al-O complex oxides were fabricated via an in-situ reduction and topochemical carbonization strategy by using hydrotalcite as the precursor. The Co δ+ -Co 2 C decorated-Co-Ni alloys were obtained via the following process: (I) after reduction, Co-Ni alloy was obtained and Co could donate electrons to Ni in the Co-Ni alloy NPs; (II) in syngas atmosphere, some of cobalt atoms on the surface of Co-Ni NPs reacted with CO and were converted to Co 2 C. Resultantly, in the reaction process, Co-Ni alloy NPs were transformed into Ni-Co alloy@Co-Co 2 C, a core-shell structure with Ni-Co alloy core and Co-Co 2 C shell. When used as the catalysts for direct ethanol synthesis (DES) from syngas, the bimetallic Co-Ni alloy@Co-Co 2 C catalyst performed excellent selectivity to ethanol, owing to the regulation of dissociatively and associatively adsorbed CO by Co δ+ -Co 2 C active sites formed on the surface of Co-Ni alloy NPs. Moreover, the mutual dilution between Co and Ni in the Co-Ni alloy NPs inhibited the generation of heavy hydrocarbons, further improving the selectivity to alcohols. The total alcohol selectivity of 43.0% and ethanol occupied 45.2 wt% could be reached over the optimal catalyst.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Shibin Lu,Ying Meng,Haibo Wang,Feifei Wang,Jiangtao Yuan,Hong Chen,Yuehua Dai,Junning Chen
Associated with the unique structure and superior properties of zeolitic imidazolate frameworks (ZIFs) of Co-based metal-organic frameworks (MOFs), we synthesized the MWCNTs@carbonaceous CoO composites of a 3D interconnected network using multi-walled carbon nanotubes (MWCNTs) as decoration through the wet chemical and pyrolysis method. Due to the mutual coordination between proper magnetic loss and strong dielectric loss together with perfect impedance match, the MWCNTs@carbonaceous CoO composites exhibit the maximal reflection loss (RL) value of −50.2 dB with 1.84 mm thickness at 14.3 GHz, absorbing bandwidth (RL ≤ −10 dB) of 13.2 GHz (4.8–18 GHz) with respect to 1.0–4.0 mm thickness range. More importantly, the content of composites added to paraffin matrix is merely 10 wt%. In addition, the synergistic effect between CoO NPs and MWCNTs is also beneficial to the highly efficient electromagnetic (EM) wave absorption of the composites. Therefore, the obtained CoO NPs/MOF-derived composites with lightweight and thin performance can be an attractive candidate of the EM wave absorptive materials.
研究领域:
材料科学
·
电磁学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF POWER SOURCES
·
2025
·
IF 7.9
Jingjing Zhang,Xia Hu,Jia Wang
The design of support materials with uniformly anchored sites is crucial for controlling the particle size distribution of platinum (Pt) and enhancing the performance of Pt-based hydrogen evolution reaction (HER) catalysts. Cobalt Metal-Organic Framework (Co-MOF)-derived carbon is a promising support for anchoring Pt nanoparticles. However, transition metal sites in Co-MOF tend to aggregate during the carbonization process. Herein, we have developed a strategy to achieved the in-situ reduction of cobalt sites by pre-treating Co-MOF in a reducing atmosphere, resulting in the hydrogen-reduced cobalt-modified nitrogen-doped carbon (Co@NOC-H 2 ) support material. As a result, a low-Pt catalyst (PtCo@NOC-H 2 ) with uniform distribution nanoscale particle size has been developed. Compared to the Co-MOF material pretreated in an nitrogen atmosphere (Co@NOC-N 2 ), Co@NOC-H 2 exhibited uniformly dispersed cobalt-platinum nanoparticles (CoPt NPs), which contributes to enhanced catalytic activity and stability in acidic media. Electrochemical measurements show that the PtCo@NOC-H 2 catalyst with a low-Pt loading (0.05 mg Pt cm −2 ) demonstrates excellent performance, with an overpotential of only 16.7 mV at a current density of 10 mA cm −2 and a Tafel slope of 37.5 mV dec −1 . Furthermore, it maintains stable performance with no significant degradation after 156 h of cycling. This study provided a feasible approach for developing cost-effective low-Pt catalysts.
✓ 已验证
产品关联
DOI
高影响因子
Science Advances
·
2023
·Vol. 9
·期 24
·
IF 13.6
Mingrui Wang,Peng Wang,Guanghui Zhang,Zening Cheng,Mengmeng Zhang,Yulong Liu,Rongtan Li,Jie Zhu,Jianyang Wang,Kai Bian,Yi Liu,Fanshu Ding,Thomas P. Senftle,Xiaowa Nie,Qiang Fu,Chunshan Song,Xinwen Guo
The decomposition of cobalt carbide (Co 2 C) to metallic cobalt in CO 2 hydrogenation results in a notable drop in the selectivity of valued C 2+ products, and the stabilization of Co 2 C remains a grand challenge. Here, we report an in situ synthesized K-Co 2 C catalyst, and the selectivity of C 2+ hydrocarbons in CO 2 hydrogenation achieves 67.3% at 300°C, 3.0 MPa. Experimental and theoretical results elucidate that CoO transforms to Co 2 C in the reaction, while the stabilization of Co 2 C is dependent on the reaction atmosphere and the K promoter. During the carburization, the K promoter and H 2 O jointly assist in the formation of surface C * species via the carboxylate intermediate, while the adsorption of C * on CoO is enhanced by the K promoter. The lifetime of the K-Co 2 C is further prolonged from 35 hours to over 200 hours by co-feeding H 2 O. This work provides a fundamental understanding toward the role of H 2 O in Co 2 C chemistry, as well as the potential of extending its application in other reactions.
研究领域:
催化化学
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化学工程
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材料科学
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可持续能源
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多相催化
✓ 已验证
DOI
高影响因子
ACS Applied Energy Materials
·
2022
·
IF 6.959
Ying Yang,Daorui Wang,Yuanyuan Wang,Zelin Li,Rui Su,Xin Wang,Tong Xu,Shuangxi Wang
Metal sulfide electrocatalysts with high activity toward the oxygen evolution reaction (OER) are crucial for renewable energy technologies. However, it remains challenging to rationally design and synthesize metal sulfides integrated with high conductivity and rich porosity to achieve a superior activity. Herein, we report a brand-new, carbonaceous Co9S8-ZnS nanotube (Co9S8-ZnS/NTC) electrocatalyst synthesized via a two-step procedure including zinc-trimesic acid (ZnBTC) fiber nanocrystallization and its assembling with ZIF-67 before solid-state transformation (including sulfuration, gas-phase ion exchange, and carbonization). It is found that rich sulfur vacancies (point defect) and a hollow cavity (3-dimensional defect) are integrated into the resulting carbonaceous Co9S8-ZnS nanotube, originated from the non-equilibrium interdiffusion, which could facilitate electron transfer and OH– transport during the oxygen evolution. As expected, the designed Co9S8-ZnS/NTC delivers a low overpotential of 290 mV, a Tafel slope of 69 mV–1, an electrical resistance of 44 Ω for OER at 10 mA cm–2 in alkaline media, and a high electrochemically active surface area and turnover frequency of 12.2 mF cm–2 and 0.70 O2 s–1, respectively, at 1.50 V, superior to single-component electrocatalysts of Co9S8 and ZnS anchored on N-doped carbon. Density functional theory calculation demonstrates that the sulfur vacancy in Co9S8-ZnS/NTC delivers the decreased theoretical overpotential (1.29 V) and the enhanced activity of its neighboring Co sites, which was also beneficial to OER kinetics. Sulfur vacancy reparation results in a much lower electrocatalytic activity (overpotential, 465 mV) for Co9S8-ZnS/NTC, indicative of its critical role in OER. The concept demonstrated in this study paves the avenue to design other high-performance non-noble electrocatalysts for OER.
研究领域:
材料科学
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电化学
·
可再生能源技术
✓ 已验证
DOI
高影响因子
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