DALTON TRANSACTIONS
·
2021
·Vol. 50
·期 48
·18061-18068
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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.
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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.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Yangxin Rong,Yuan Chen,Jihua Zheng,Yan Zhao,Qiuping Li
Herein, a series of alpha-Co(OH) 2 /reduced graphene oxide (rGO) microfilms and film-based nanodevices were developed via a new scalable technique. Due to the unique hexagonal nanoplates of ultrathin alpha-Co(OH) 2 and the intrinsically conductive nature of rGO sheets, such thin films not only can improve the conductivity of alpha-Co(OH) 2 and prevent the re-stacking of alpha-Co(OH) 2 and rGO sheets but also short the transport routes of electrons and ions between the electrode and the electrolyte. The optimized alpha-Co(OH) 2 /rGO flexible electrode presents high specific capacitance (273.86 mF/cm 2 at 0.1 mA/cm 2 ), advanced rate capability, and excellent coulombic efficiency. Simultaneously, in-sandwich symmetric and asymmetric supercapacitors assembled with polyvinyl alcohol-KOH gel as the solid-state electrolyte achieved high areal and volumetric specific capacitances. Furthermore, a self-assembled planar alpha-Co(OH) 2 /rGO micro-supercapacitor (MSC) delivers high specific area capacitance (130F/cm 2 at 0.5 mA/cm 2 ) and excellent energy density (20 mWh/cm 3 @56 mW/cm 3 ), which are superior to most of the recently reported carbon-based and metal hydroxides/oxides/sulfides-based planar MSCs. Also, our planar MSC shows excellent cycling performance, good flexibility, and mechanical stability. This work promotes the syntheses of other two-dimensional metal hydroxides/rGO composite film for high-performance flexible micro-electronics.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2020
·
IF 4.939
Li-Wen Jiang,Yuan Huang,Bing-Bing Chen,Jian-Qiu Zhou,Hong Liu,Jian-Jun Wang
Hydrogen production via alkaline water electrolysis is of significant interest. However, the additional water dissociation step makes the Volmer step a relatively more sluggish kinetics and consequently leads to a slower reaction rate than that in acidic solution. Herein, we demonstrate an effective strategy that Co(OH) 2 can promote the Volmer process by accelerating water dissociation and enhance the electrocatalytic performance of CoP toward alkaline hydrogen evolution reaction . The Co(OH) 2 nanoplates are electrochemically induced in-situ generated to form a nanotree-like structure with porous CoP nanowires , endowing the hybrid electrocatalyst with superior charge transportation, more exposed active sites, and enhanced reaction kinetics. This strategy may be extended to other phosphides and chalcogenides and provide insight into the design and fabrication of efficient alkaline HER catalysts.
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JOURNAL OF ENVIRONMENTAL MANAGEMENT
·
2023
·
IF 8.7
Zuozhu Yin,Min Li,Zihao Li,Yuanting Deng,Mingshan Xue,Yuhua Chen,Junfei Ou,Sheng Lei,Yidan Luo,Chan Xie
Traditional membranes are inefficient in treating highly toxic organic pollutants and oily wastewater in harsh environments, which is difficult to meet the growing demand for green development. Herein, the Co(OH) 2 @stearic acid nanocellulose-based membrane was prepared by depositing Co(OH) 2 on the nanocellulose-based membrane (NBM) through chemical soaking method, which enables efficient oil/water mixtures separation and degradation of pollutants by photocatalysis in harsh environments. The Co(OH) 2 @stearic acid nanocellulose-based membrane (Co(OH) 2 @stearic acid NBM) shows good photocatalytic degradation performance for methylene blue pollutants in harsh environment, and has significant degradation rate (93.66%). At the same time, the Co(OH) 2 @stearic acid NBM with superhydrophobicity and superoleophilicity also exhibits respectable oil/water mixtures separation performance (n-Hexane, dimethyl carbonate, chloroform and toluene) under harsh environment (strong acid/strong alkali), which has an excellent oil-water mixtures separation flux of 87 L·m −2 ·h −1 (n-Hexane/water) and oil-water mixture separation efficiency of over 93% (n-Hexane/water). In addition, this robust Co(OH) 2 @stearic acid NBM shows good self-cleaning and recycling performance. Even though seven oil-water separation tests have been carried out under harsh environment, it can still maintain respectable oil-water mixture separation rate and flux. The multifunctional membrane has excellent resistance to harsh environments, oil-water separation and pollutant degradation can be performed even in harsh environments, which provides a convenient way to treat sewage under harsh conditions efficiently and has great potential in practical application.
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GREEN CHEMISTRY
·
2017
·Vol. 19
·期 24
·5809-5817
·
IF 9.125
Haidong Yang,Yu Long,Yan Zhu,Ziming Zhao,Ping Ma,Jun Jin,Jiantai Ma
The exploration of highly efficient nonprecious metal-based electrocatalysts for the oxygen evolution reaction (OER) is of great importance for potential applications in sustainable energy conversion. Recently, the layered metal hydroxide (LMH) family is receiving extensive research attention owing to its unique structural properties. However, the gained electrocatalytic performance of LMH-based catalysts for the OER is still far from the state-of-the-art requirements because of its finite number and poor reactivity of exposed active sites. In response, we synthesized crystal lattice distorted ultrathin cobalt hydroxide (denoted as CLD-u-Co(OH)2) nanosheets with a great number of efficient catalytic active sites through the introduction of Ga into ultrathin Co(OH)2, followed by a selective removal of Ga, denoted as the “introduction @ removal” process. As a result, the crystal lattice distortion confined inside CLD-u-Co(OH)2 generates abundant elongated Co–OOH bonds on exposed (10) facets serving as efficient catalytic active sites for the OER. Besides, the optimized amount of “introduction @ removal” of Ga (4 at%) allows for an exquisite balance between distortion engineering and electrical conductivity, synergistically. The as-prepared CLD-u-Co(OH)2 achieves an overpotential of 265 mV at a current density of 10 mA cm−−2, an unexpectedly small Tafel slope of 47 mV dec−−1, and a long-term stability (beyond 20 h) in basic media. It is mainly attributed to abundant catalytic active sites, robust reactivity per site, and good electrical conductivity. Furthermore, the green and sustainable engineering of crystal lattice distortion to improve the intrinsic electrocatalytic activity of CLD-u-Co(OH)2 nanosheets presented in this work may provide a promising strategy to design and synthesize newly highly efficient LMH-based electrocatalysts for the OER.
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CRYSTENGCOMM
·
2017
·Vol. 19
·期 42
·6305-6313
·
IF 3.474
Abraham Adenle,De-Kun Ma,De-Peng Qu,Wei Chen,Shaoming Huang
The fabrication of hollow micro- and nanocrystals can not only increase the specific surface area of the materials but also benefit the understanding of the crystal facet-dependent catalytic activity. On the other hand, both the rational doping of heteroatoms and loading of co-catalysts can enhance the photocatalytic activity of semiconductor-based photocatalysts. However, up to now, there have been only a few reports on the synergetic effect of the two. In this work, BiVO4 hollow microplates (HMPs) and solid microplates (SMPs) were synthesized by a facile hydrothermal route, and B3+ ion-doped BiVO4 HMPs loaded with Co(OH)2 nanoparticles [Co(OH)2/B–BiVO4] were prepared through a one-step impregnation method. The as-prepared products were characterized in detail. The formation mechanism of BiVO4 HMPs was also proposed on the basis of time-dependent SEM observations and XRD analyses. Taking rhodamine B (RhB) as a kind of pollutant model, the photocatalytic activities of BiVO4 HMPs, BiVO4 SMPs, B3+ ion-doped BiVO4 HMPs, BiVO4 HMPs loaded with Co(OH)2 nanoparticles, and Co(OH)2/B–BiVO4 HMPs were systematically studied. The results show that {010}-dominant BiVO4 SMPs exhibited better photocatalytic activity for the degradation of RhB than {010} and {110}-dominant BiVO4 HMPs. In addition, the doping of B3+ ions and loading of Co(OH)2 nanoparticles could synergistically enhance the photocatalytic activity of BiVO4 HMPs. The present study not only provides reliable evidence for the crystal facet-dependent photocatalytic activity of BiVO4 but also develops a new strategy for enhancing its photocatalytic activity.
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DIAMOND AND RELATED MATERIALS
·
2024
·
IF 4.3
M. Thangarasu,P. Priyanka,K.L. Meghanathan,M. Parthibavarman,Sucheta Gaikwad,S. Vadivel,S. Rathinavel,D.R.P. Rajarathnam,Nouf H. Alotaibi,Saikh Mohammad
The issue of inadequate conductivity of electrons is consistently linked to the electrode material for pseudocapacitor , which hinders the complete utilization of the active material. In order to address this issue effectively, we have developed a composite material consisting of carbon nanotubes (CNTs) that are extremely conductive and wrapped around pseudocapacitive Co(OH) 2 nanobricks. The supercapacitor is created in our laboratory using a modified hydrothermal method (MHT) that allows for in situ growth. An electrochemical study confirms that the Co(OH) 2 @MWCNT electrode is extremely reactive, resulting in a maximum specific capacitance of 1911 Fg −1 (at 1 Ag −1 ). Furthermore, after 10,000 cycles of execution, it displays remarkable stability over the long term, with 96.5 % retention at a constant current density of 1 Ag −1 . In addition, the ASC has a significant energy density of 89.3 Whkg −1 at 1 Ag −1 . Furthermore, the device maintains an excellent energy density of 55.5 Whkg −1 while operating at a power density of 1015 Wkg −1 . In addition, the Co(OH) 2 @CNT//AC ASC has remarkable long-term cycling stability, with a just 4 % decrease in capacitance after 10,000 cycles. Furthermore, the device continues to maintain a commendable Coulombic efficiency of 83.5 %. These promising results indicate that these materials have the potential to be used in economical and reliable energy storage technologies .
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2024
·
IF 4.1
Xingnian Duan,Jianmei Cen,Xiaoyu Qiu,Xixiang Liu
The development of high-performance and cost-effective electrocatalysts for oxygen evolution reactions (OER) is key to renewable energy conversion and storage technologies. In this paper, a hierarchical Co(OH) 2 -MoO 3 nanosheets with petal-like architecture was prepared by a simple one-step hydrothermal method using ZIF-67/NF as a precursor, and it was used as a direct electrocatalyst for OER. Notably, this petal-like Co(OH) 2 -MoO 3 /NF layered nanosheets not only prevent the agglomeration of nanostructured material , but also facilitate the complete penetration and diffusion of electrolyte. In addition, due to the strong electronic interaction between Co(OH) 2 and MoO 3 in the Co(OH) 2 -MoO 3 /NF system, Co(OH) 2 -MoO 3 /NF exhibits excellent electrocatalytic OER performance. It has a low overpotential of 273 mV at 10 mA cm −2 and excellent stability. This study provides a simple and effective strategy for the rational design and structural evolution of MOF-derived materials to achieve inexpensive and effective electrocatalysis.
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INORGANIC CHEMISTRY COMMUNICATIONS
·
2019
·
IF 1.795
Mingping He,Wanli Xu,Zhenqiang Dong,Yuechao Wu,Liang Lv
Carbon cloth (CC) is widely used as flexible substrate for supercapacitors , but its space utilization is low. In order to overcome this shortcoming, a new strategy was proposed to fill the gaps and voids in CC by anchoring polyaniline/phytic acid hydrogel (PAH) on CC. Then Co(OH) 2 was electrodeposited on PAH/CC to obtain flexible electrode for supercapacitor. Due to the high mass loading of Co(OH) 2 /PAH (9.83 mg cm −2 ), Co(OH) 2 /PAH/CC provided excellent areal capacitance of 8142.5 mF cm −2 at current density of 5 mA cm −2 . The symmetrical device demonstrated excellent energy density of 201.5 μWh cm −2 at power density of 3000 μW cm −2 , which is larger than those of most devices reported previously. This strategy of anchoring conductive hydrogel network in macroporous frame opens up a new way to fabricate flexible supercapacitor electrode with high areal capacitance and energy density.
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Journal of Materials Chemistry A
·
2017
·Vol. 5
·期 22
·11163-11170
·
IF 8.867
Lifeng Hang,Yiqiang Sun,Dandan Men,Shengwen Liu,Qian Zhao,Weiping Cai,Yue Li
Hierarchical micro/nanostructured C doped Co/Co3O4 hollow spheres were prepared by two-step treatment (annealing at 600 °C in an Ar atmosphere and then at 250 °C in air) of PS@Co(OH)2 core–shell structures templated from PS microspheres without any modification. In 1 M KOH, such hollow nanospheres showed an overpotential of 352 mV at a benchmark oxygen evolution reaction (OER) current density of 10 mA cm−2, which was lower than that of RuO2 (364 mV), Co3O4 hollow nanospheres (410 mV) and C-Co/Co3O4 nanoparticles (462 mV). Importantly, the C-Co/Co3O4 hollow spheres exhibited a small onset potential (1.49 V) due to their more active sites, higher electrical conductivity, larger specific surface area, and excellent electron and ion diffusion permeability. This work provides a strategy to design and fabricate earth-abundant, low-cost electrocatalysts for water splitting in practical applications.
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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.
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