JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
·
2015
·Vol. 78
·期 2
·293-298
·
IF 1.532
Cui Hongtao,Ma Wenle,Wang Li,Xue Junying
Abstract
In this work, α-Co(OH) 2 monolayer nanosheets were prepared by an intercalation agent-free route utilizing a precipitation reaction between epoxide and aqueous complexes of cobalt ions ([Co(H 2 O) 6 ] 2+ ). The protonation and the following ring-opening reaction of epoxide promoted the hydrolysis of [Co(H 2 O) 6 ] 2+ , leading to the formation of α-Co(OH) 2 nanosheets. The obtained nanosheets were then exfoliated to monolayer nanosheets in formamide under ultrasonic vibration. A possible exfoliation mechanism is proposed for the exfoliating process of α-Co(OH) 2 nanosheets. The water molecules incorporated in the layered structure of α-Co(OH) 2 are considered to be the key medium for the layer exfoliation. It seems that the water molecules coordinated with the cobalt ions weakened the interlayer interaction. Therefore, the extraction of water molecules by formamide readily broke the interlayer connection in α-Co(OH) 2 , resulting in the exfoliation of nanosheets. Graphical Abstract α-Co(OH) 2 monolayer nanosheets were prepared by an intercalation agent-free route utilizing a precipitation reaction between epoxide and aqueous complexes of cobalt ions ([Co(H 2 O) 6 ] 2+ ).
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2021
·Vol. 32
·期 10
·13941-13947
·
IF 2.478
Liu Ying,Cao Bo,Zhang Xu,Luo Rong,Luo Chunhua,Lin Hechun,Peng Hui
Layered Co(OH) 2 has been regarded as a potential candidate for pseudocapacitor electrode material, but it is limited by its poor conductivity and low surface area. Herein, carbonated multi-walled carbon nanotubes (MWCNTs-COOH) were used to improve the conductivity of α-Co(OH) 2 nanocomposites. α-Co(OH) 2 nanoflowers were successfully grown and tangled with MWCNTs-COOH to form a randomly oriented network structure mediated by ammonia using water-methanol as co-solvent at room temperature. The capacitance performances of the obtained α-Co(OH) 2 @MWCNT-COOH composites were investigated to find that MWCNT-COOH improved the specific capacitance efficiently. Especially, in the presence of 20% in mole of MWCNT-COOH, the composite gave rise to the high specific capacitance of 1027 F/g at the current density of 2 A/g with good cycle stability, whose specific capacitance remained 78% of its original even after 5000 cycles at 30 A/g current. The large surface area and strengthening the conductivity of the composites lead to the improvement of efficiency in charge/discharge process.
研究领域:
材料科学
·
能源存储
✓ 已验证
DOI
高影响因子
JOURNAL OF NANOPARTICLE RESEARCH
·
2020
·Vol. 22
·期 2
·1-12
·
IF 2.132
Sun Xueying,Li Siqi,Liu Rongmei,Sun Xiulun,Liu Xinjie,Li Anran,Li Wen
In this work, we designed a simple hydrothermal synthetic method for a ZnCo-PBA@α-Co(OH) 2 nanosphere@nanosheet material with good electrochemical properties. The obtained material had a specific capacitance of 423.92 F g −1 at 1 A g −1 and a cycling retention ratio of 78.48% after 1000 cycles at 5 A g −1 . A hybrid supercapacitor device (ZnCo-PBA@α-Co(OH) 2 //AC) assembled with activated carbon as the negative electrode had a specific capacitance of 122.4 F g −1 at 1 A g −1 , a cycling retention rate of 73.53% after 5000 cycles at 5 A g −1 , and a very high energy density of 49.13 Wh kg −1 at power density of 1734.0 W kg −1 . The significantly improved electrochemical performance of the ZnCo-PBA@α-Co(OH) 2 nanocomposites can be attributed to the positive synergistic effects of the porous structure of the PBA material and the large specific surface area of the α-Co(OH) 2 nanosheets, on the ion permeability and number of active sites in the reinforcing material; thus, this composite is a potential material for use in future energy storage systems.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Yu Tian,Xiaoru An,Xiaonan Du,Dalei Chang,Hong Li,Yue Hua,Xiuling Zhang,Jingsen Zhang,Lanbo Di
α-Co(OH) 2 has important applications in environmental, energy and catalysis applications. However, a complicated and harsh process is required for its production. Therefore, it is necessary to develop a rapid, facile, and green approach for the controllable synthesis of α-Co(OH) 2 . In this study, we successfully synthesized α-Co(OH) 2 supported on multiwalled carbon nanotubes (MWCNT) (α-Co(OH) 2 /MWCNT) by the plasma treatment of a mixture of cobalt nitrate and MWCNT in water without adding any other chemical reagents. The controllable synthesis of α-Co(OH) 2 was achieved only by adjusting the plasma conditions and support functionalization. The reduction of p -nitrophenol (4-NP) as a model using NaBH 4 was used to evaluate the performance of the obtained α-Co(OH) 2 /MWCNT catalysts. The results revealed that the sample prepared with 15 min of plasma treatment using H 2 /Ar as the working gas (α-Co(OH) 2 /MWCNT-15) had a good crystalline phase structure and showed excellent 4-NP reduction performance with a reaction rate constant as high as 1.97 min −1 . Structural characterization and electrochemical analyses of the different catalysts indicated that α-Co(OH) 2 /MWCNT-15 contains abundant defects, a large layer spacing, and abundant lattice sites for hydrogen adsorption, which are conducive to the adsorption of more active hydrogen species and 4-NP, and thus lead to significantly accelerated catalytic reduction of 4-NP.
研究领域:
材料科学
·
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
Journal of Energy Storage
·
2021
·
IF 6.583
Weizhi Gong,Mingjun Wang,Yi An,Junli Wang,Liexing Zhou,Yi Xia,Chunjian Wang,Kun Dong,Cheng Pan,Rongfeng Zhou
Cycling stability and specific capacitance are two of important performance parameters for pseudocapacitive electrodes under frequent charging and discharging. Herein, we present a facile solvothermal approach to rationally design and fabricate chiffon-like and hydrotalcite-like α-Co(OH) 2 nanoflakes for extrinsic pseudocapacitive electrode, which exhibits linear galvanostatic discharge behavior and superior charge-storage performance, including high capacitance of 475 F g −1 at 1 A g −1 , excellent rate capability and superb cycling stability with capacitance retention of 93.9% after 10000 cycles at 10 A g −1 . The superior performance is mostly attributed to the good electrical conductivity and stable microstructure of the hydrotalcite-like α-Co(OH) 2 nanoflakes and the abundant redox active sites on the chiffon-like nanoflakes with short and facile electron transport. In addition, other α-Co(OH) 2 samples with different morphologies and size as contrast are prepared and discussed, indicating that the morphology/size design and optimization of the α-Co(OH) 2 could greatly improve the electrochemical energy-storage performance. The findings demonstrate that the chiffon-like and hydrotalcite-like α-Co(OH) 2 nanoflakes have a great practical application potential in long-life and high-performance supercapacitors . This study also presents a facile way to design and prepare nanoflake-like materials with adjustable lateral size and thickness from spherical morphology consisting of nanoflakes.
研究领域:
材料科学
·
电化学
·
纳米技术
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
DALTON TRANSACTIONS
·
2021
·Vol. 50
·期 48
·18061-18068
·
IF 4.39
Jiahui Guo,Xueqing Feng,Songrui Wang,Qikang Wu,Shanshan Lv,Yan Zhou,Han Li,Zheng Chen,Yuzhong Zhang
Novel hexagonal α-cobalt hydroxide nanosheets are synthesized through a 2-methylimidazole-induced hydrolysis strategy with cetyltrimethylammonium bromide (CTAB) as a surfactant. The weak alkaline environment provides favorable conditions for the formation of metastable α-Co(OH)2, while the same raw material will produce β-Co(OH)2 when a strong alkali solution is used. CTAB plays a vital role not only in hexagonal oriented growth, but also in the formation of the hydrotalcite-like structure of α-Co(OH)2 with high crystallinity. The crystallinity of both α- and β-Co(OH)2 is very poor without CTAB as a surfactant. The Co in this Co(OH)2−x layer presents most of the CoII and a small part of the CoIII, and the interlayer nitrate anion balances the positive charge of the host layer. The redox function produced by the CoII and CoIII of α-Co(OH)2 together with the large layer spacing jointly promotes the electron and mass transfer. The use of hydrazine hydrate for transfer hydrogenation involves the transport of protons and electrons produced by decomposition, and the rapid transport is bound to be conducive to the reduction process. Nitro compounds with varieties of functional groups can be smoothly reduced to the corresponding amines with high selectivity, when α-Co(OH)2 was used as a catalyst under mild conditions.
研究领域:
材料科学
·
催化
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED SURFACE SCIENCE
·
2025
·
IF 6.9
Mengke Li,Yang Yang,Yajie Zhang,XinZhuo Liu,Yulan Li,Xiaobin Niu
NiFe-layered double hydroxides (NiFe LDHs) are regarded as outstanding electrocatalysts for the oxygen evolution reaction (OER), but the inherent charge transport limitations hinder their practical application. Herein, we developed a 3D hierarchical α-Co(OH) 2 /NiFe LDH/NF composite catalyst via a simple electrodeposition-hydrothermal method. The introduction of α-Co(OH) 2 enables interfacial electron modulation with NiFe LDH, driving electron transfer from Ni/Co sites to Fe centers via multi-pathway coupling channels (Ni–O–Fe, Ni–O–Co, Co–O–Fe). This electron redistribution creates an optimized coordination environment that promotes the formation of high-valence Ni and Co species, subsequently facilitating the in situ formation of highly active phases (γ-NiFeOOH and CoOOH) during the OER process. The derived γ-NiFeOOH provides superior intrinsic activity, while the coexisting. CoOOH significantly enhances charge transport due to its high electronic conductivity. As a result, the composite achieves an overpotential of only 285 mV at a current density of 500 mA cm −2 , outperforming both NiFe LDH (372 mV) and α-Co(OH) 2 (441 mV). Additionally, this catalyst shows an excellent long-term stability at 100 mA cm −2 for 120 h. This work demonstrates that interfacial electronic modulation offers a strategy for designing efficient and durable OER catalysts capable of operating at industrial current densities.
研究领域:
电化学
·
材料科学
·
催化
·
能量存储与转换
✓ 已验证
产品关联
DOI
高影响因子
LANGMUIR
·
2025
·
IF 3.9
Xiaoru An,Xiaonan Du,Hong Li,Fei Gao,Yue Hua,Xiuling Zhang,Jingsen Zhang,Lanbo Di
Electrochemical nitrate reduction reaction (eNO3RR) with Co-based catalysts provides a sustainable and efficient approach to wastewater purification and nitrogen recovery. However, their inevitable and uncontrollable reconstruction during the eNO3RR leads to uncertain actual active sites and a confused understanding of the mechanism. Herein, the active sites and structural evolution of α-Co(OH)2/CC during the eNO3RR process were investigated via in situ and ex situ characterizations. The results show that α-Co(OH)2 nanosheets are converted to β-Co(OH)2 in a strongly alkaline electrolyte and then act as active sites to adsorb NO3– and spontaneously react to generate CoOOH. Whereas CoOOH is swiftly reduced to β-Co(OH)2 at negative cathodic potential, realizing a nitrate-electrically mediated cyclic evolution process and synergistically catalyzing the eNO3RR. Consequently, α-Co(OH)2/CC achieves a Faradaic efficiency as high as 92% at −0.1 V vs RHE and a high NH3 yield rate of 338 mmol·gcat–1·h–1 under −0.6 V vs RHE. This work offers novel insight into the structural evolution and catalytic behavior of Co-based catalysts in eNO3RR.
研究领域:
电催化
·
环境化学
·
材料科学
·
可持续能源
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Physical Chemistry C
·
2013
·
IF 4.814
X. Ge,C. D. Gu,X. L. Wang,J. P. Tu
An ionothermal strategy is developed to synthesize hydrotalcite-like α-Co(OH)2 sheets. The structure and interlayer chemistry of α-Co(OH)2 are facilely manipulated, thus determining its pseudocapacitive performance. Significantly, a very large space of 11.2 Å in (003) plane induced by various intercalated species is found in the ionothermal synthesized α-Co(OH)2 obtained at 210 °C (210-α-Co(OH)2), which delivers a better pseudocapacitive performance. Annealing the synthesized α-Co(OH)2 generates mesoporous Co3O4 sheets or nanoparticles, which depends on the structure of the precursors. More defects in the α-Co(OH)2 precursor provide larger driving force during the nucleation of Co3O4 nanocrystals, thus reducing the grain size. The architecture of the 210-Co3O4 derived from 210-α-Co(OH)2 is featured as self-supporting mesoporous nanosheets composed of ∼5 nm sized grains. The fine grains and ultralarge specific surface area of ∼113.5 m2 g–1 in the 210-Co3O4 can trigger the formation of CoO intermediate during lithium ion insertion into the Co3O4. The 210-Co3O4 exhibits superior cycling performance as electrode for lithium ion battery and supercapacitor over the other Co3O4 samples due to its nanocrystallite constructed mesoporous sheet structure, which has a higher strain accommodation capability. The underlying mechanism discussed in this work provides guidance on structural design of advanced energy storage materials.
研究领域:
材料科学
·
电化学
·
储能
·
纳米材料
·
无机合成
✓ 已验证
DOI
高影响因子
ACS Omega
·
2019
·
IF 2.584
Bo Cao,Chunhua Luo,Jie Lao,Hanqing Chen,Ruijuan Qi,Hechun Lin,Hui Peng
Layered cobalt hydroxides are cost-efficient electrocatalysts for oxygen evolution reaction (OER) in the field of energy conversion. Herein, we developed a facile synthesis method of 3d transition-metal-doped α-Co(OH)2 nanomaterials mediated with ammonia in water–methanol at room temperature. The doping of Cu2+ and Ni2+ leads to flower-like nanostructures similar to pure α-Co(OH)2, whereas the doping of Fe2+ produces nanoparticles with more than 2 times larger surface area in comparison with the Cu2+- and Ni2+-doped nanoflowers. The obtained dispersion with the addition of Nafion can be used directly as an electrocatalyst for OER with excellent catalytic activity, especially that the overpotential of Fe2+ doped is as low as 290 mV at 10 mA cm–2 and the turnover frequency is improved by 3 times as compared with that of α-Co(OH)2. Furthermore, the catalyst can be loaded onto foam nickel, which presents excellent durability with the current density unchanged under continuous chronoamperometry reaction for as long as 12 h and almost quantitative faradaic efficiency. The superior electrocatalytic properties combined with the simple synthesis without the tedious purification procedure is very promising for OER.
研究领域:
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2019
·
IF 4.561
Xiangrui Meng,Yijin Mi,Dongling Jia,Ning Guo,Yarui An,Yuqing Miao
Co hydroxide polymorphs (green α-Co(OH) 2 , red β-Co(OH) 2 and brown β-Co(OH) 3 ) formed at separate positions in a test-tube. Diffusion of hydrazine hydrate downward in agar gel facilitated the reaction between hydrazine and Co 2+ leading a dilatational wave of reactant concentration. The resulting periodic Liesegang bands of α-Co(OH) 2 were observed due to the diffusion hindrance of reactants. It can be deduced that the high concentration of Co 2+ causes formation of α-Co(OH) 2 while the low concentrations produce β-Co(OH) 2 . β-Co(OH) 2 is oxidized readily to form brown β-Co(OH) 3 at the upper area of agar gel with high alkali condition and O 2 distribution. This study is helpful to learn the formation of more than one product and prepare multiple materials in single chemical reaction system. In addition, the obtained α-Co(OH) 2 has been stabilized in the gel medium for at least 3 months. It may facilitate its application in many areas especially in electrochemical area since α-Co(OH) 2 typically exhibits higher conductivity and electrocatalysis than β-Co(OH) 2 while in the past its application often is limited by thermodynamically instability.
研究领域:
材料科学
·
化学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2013
·
IF 2.39
Hongtao Cui,Yunan Zhao,Wanzhong Ren,Minmin Wang,Yan Liu
In this work, α-Co(OH) 2 and β-Co(OH) 2 nanosheets were selectively synthesized through an epoxide precipitation reaction under mediation of fluoride ions. The protonation and ring opening reaction of propylene oxide promoted the hydrolysis [Co(H 2 O) 6 ] 2+ to form a mixed phase of α-Co(OH) 2 and Co 2 (OH) 3 Cl in the condition of no existence of fluoride ions. Due to the enhanced hydrolysis of [Co(H 2 O) 6 ] 2+ under function of fluoride ions, pure phases of α-Co(OH) 2 and β-Co(OH) 2 were formed respectively at different concentration of fluoride ions. The mild reaction condition of this route allows for large scale synthesis of cobalt hydroxide nanosheets, which is only limited by volume of the vessel used as reactor.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）