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Saisai Zhou, Zhaochun Ye, Sizhong Hu, Chen Hao, Xiaohong Wang, Chengxiang Huang, Fangsheng Wu
Zeolitic imidazolate frameworks have stimulated great attention due to their potential applications in energy storage, catalysis, gas sensing, drug delivery etc. In this paper, the three-dimensional porous nanomaterial Co3O4/ZnCo2O4/CuO with hollow polyhedral nanocage structures and highly enhanced electrochemical performances was synthesized successfully by a zeolitic imidazolate framework-67 route. The composites hold the shape of the ZIF-67 templates well and the shell has multiple compositions. In the process, we first synthesized the nanostructure hydroxide precursors and then transformed them into the corresponding metal oxide composites by thermal annealing in air...
August 10, 2018: Nanoscale
Man Yang, Yunfeng Li, Yue Yu, Xianchun Liu, Zhan Shi, Yan Xing
In this work, a series of three-dimensional porous flower-like zinc doped NiCo2 O4 (ZNCO) nanostructures with different Zn doping level are successfully prepared by a facile solvothermal process without using any templets. The obtained products are characterized by various techniques, and their electrocatalytic performances are also assessed by the oxygen evolution reaction (OER). According to the electrochemical characterization, it is demonstrated that ZNCO-0.15 (i.e., Zn0.15 Ni0.85 Co2 O4 ) nanoflowers show a lower overpotential, smaller Tafel slope, higher electrochemical active surface area (ECSA), as well as a larger turnover frequency (TOF) value than those of Co3 O4 , NiCo2 O4 , and ZnCo2 O4 nanoflowers, indicating that introduction of an optimal content of zinc ions plays an important role in enhancing electrocatalytic performances for OER...
June 12, 2018: Chemistry: a European Journal
JinCheng Du, YuHai Tang, Yu Wang, PengHui Shi, JinChen Fan, QunJie Xu, YuLin Min
In this work, we report a facile route to fabricate a ZnCo2O4 nanosheet derived from metal-organic frameworks. The as-prepared ZnCo2O4 nanosheet material for lithium-ion batteries shows an excellent electrochemical performance. The obtained ZnCo2O4 nanosheet delivers a high reversible capacity of 1640.8 mA h g-1 at a current density of 100 mA g-1 after 50 cycles. More importantly, even at a current density of 1500 mA g-1, the electrode material still exhibits a discharge capacity of 581.3 mA h g-1 after 190 cycles...
June 5, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Haowen Liu, Qihong Hu
In this work, novel secondary assembled micro/nano porous spheres ZnCo2 O4 were firstly prepared by combining the hydrothermal method with post-synthesis calcinations. The structure and morphology of the obtained powder were characterized by x-ray powder diffraction and field emission-scanning electron microscopy. As the anode material of lithium-ion half-cells, the as-prepared ZnCo2 O4 delivered a very high capacity, extra cycling stability and excellent rate capability. A discharge capacity of 950 mAh g-1 with up to 99...
August 10, 2018: Nanotechnology
Jia Yu, Yanlei Wang, Lihui Mou, Daliang Fang, Shimou Chen, Suojiang Zhang
In allusion to traditional transition-metal oxide (TMO) anodes for lithium-ion batteries, which face severe volume variation and poor conductivity, herein a bimetal oxide dual-composite strategy based on two-dimensional (2D)-mosaic three-dimensional (3D)-gradient design is proposed. Inspired by natural mosaic dominance phenomena, Zn1-x Cox O/ZnCo2 O4 2D-mosaic-hybrid mesoporous ultrathin nanosheets serve as building blocks to assemble into a 3D Zn-Co hierarchical framework. Moreover, a series of derivative frameworks with high evolution are controllably synthesized, based on which a facile one-pot synthesis process can be developed...
February 27, 2018: ACS Nano
Qiang Zhou, Qidong Zhao, Wei Xiong, Xinyong Li, Jianan Li, Libin Zeng
Aiming at promoting the photocatalytic performance of spinel oxides, an efficient method of constructing hollow porous zinc cobaltate (Znx Co3- x O4 ) nanocubes was established in this work. Bimetallic zeolitic imidazolate frameworks (ZIFs) were prepared through a facile self-assembly strategy, then hollow Znx Co3- x O4 nanocubes were obtained by calcining the bimetallic ZIFs precursor. The structural features and optical properties of the Znx Co3- x O4 nanocubes were comprehensively investigated by a series of characterization techniques...
April 15, 2018: Journal of Colloid and Interface Science
Beihong Liu, Hui Liu, Mengfang Liang, Lixiang Liu, Zhaolin Lv, Hang Zhou, Hong Guo
Hollow octahedral ZnCo2 O4 nanocages assembled from ultrathin 2D nanosheets are prepared through facile fast simultaneous coordinating etching and thermal processes. Electrochemical results show that the hollow octahedral ZnCo2 O4 nanocage is an outstanding anode material for LIBs with a high reversible discharge capacity of 1025 mA h g-1 at 500 mA g-1 after 200 cycles, and an outstanding rate capability of 525 mA h g-1 at 4 A g-1 . Moreover, this simple, low cost and fast process could be useful for the construction of many other hollow advanced materials for supercapacitors, sensors and other novel energy and environmental applications...
November 16, 2017: Nanoscale
Yisi Liu, Hao Jiang, Jiayu Hao, Yulong Liu, Haibo Shen, Wenzhang Li, Jie Li
Aluminum-air battery is a promising candidate for large-scale energy applications because of its low cost and high energy density. Remarkably, tremendous efforts have been concentrated on developing efficient and stable cathode electrocatalysts toward the oxygen reduction reaction. In this work, a hydrothermal-calcination approach was utilized to prepare novel reduced graphene oxide (rGO)-supported hollow ZnO/ZnCo2 O4 nanoparticle-embedded carbon nanocages (ZnO/ZnCo2 O4 /C@rGO) using a zeolitic imidazolate framework (ZIF-67)/graphene oxide/zinc nitrate composite as the precursor...
September 20, 2017: ACS Applied Materials & Interfaces
Buddha Deka Boruah, Arnab Maji, Abha Misra
Herein, a novel heterostructure was fabricated by combining electrochemically and optically active materials to achieve a high capacitive response of 896 F g-1 at 5 A g-1 . A network of ZnCo2 O4 nanorods (NRs) was directly grown on a three-dimensional matrix of H : ZnO NRs (ZnCo2 O4 /H : ZnO NRs) that offered synergistic advantages by providing an optimum ion/charge transportation path, large electrochemically active surface area, and stable capacitive response during the electrolytic process. Furthermore, the fabricated solid-state asymmetric supercapacitor ZnCo2 O4 /H : ZnO NRs//activated carbon induced a large potential window of 1...
July 13, 2017: Nanoscale
Won-Tae Koo, Seon-Jin Choi, Ji-Soo Jang, Il-Doo Kim
To achieve the rational design of nanostructures for superior gas sensors, the ultrasmall nanoparticles (NPs) loaded on ternary metal oxide (TMO) hollow spheres (HS) were synthesized by using the polystyrene (PS) sphere template and bimetallic metal-organic framework (BM-MOFs) mold. The zinc and cobalt based zeolite imidazole frameworks (BM-ZIFs) encapsulating ultrasmall Pd NPs (2-3 nm) were assembled on PS spheres at room temperature. After calcination at 450 °C, these nanoscale Pd particles were effectively infiltrated on the surface of ZnO/ZnCo2O4 HSs...
March 22, 2017: Scientific Reports
Yu Pan, Hong Gao, Mingyi Zhang, Lu Li, Guangning Wang, Xinyuan Shan
Hierarchical ZnCo2O4@Ni(OH)2 sheet composite structures on Ni foam were rationally designed and successfully synthesized. The ZnCo2O4 micro-sheets grown on Ni foam served as the skeleton to improve the electrical conductivity of redox active Ni(OH)2 materials, providing more electroactive sites for the faradaic reaction, and solidify the Ni(OH)2 materials onto Ni foam as a current collector. The electrode of ZnCo2O4@Ni(OH)2 showed an ultrahigh areal capacitance of 4.6F/cm(2) at a current density of 2mA/cm(2)...
July 1, 2017: Journal of Colloid and Interface Science
Wei Shi, Haitao Zhao, Bingan Lu
In this paper ZnCo2 O4 nanowall arrays (NWAs) were first obtained through self-assembly followed by calcination. Then atomic layer deposition was used to fabricate core-shell ZnCo2 O4 @TiO2 NWAs as anode materials for lithium ion batteries (LIBs). The hierarchical NWA nanostructure has fast ion diffusion and electron transport at the electrode/electrolyte interface, while the excellent chemical stability of the TiO2 shell can protect the ZnCo2 O4 NWAs from volume expansion during the charge and discharge processes...
April 21, 2017: Nanotechnology
Guoxin Gao, Hao Bin Wu, Bitao Dong, Shujiang Ding, Xiong Wen David Lou
The growth of ultrathin ZnCo2 O4 nanosheets on reduced graphene oxide (denoted as rGO/ZnCo2 O4 ) via a facile low-temperature solution method combined with a subsequent annealing treatment is reported. With the assistance of citrate, interconnected ZnCo2 O4 nanosheets can assemble into hierarchically porous overlays on both sides of rGO sheets. Such a hybrid nanostructure would effectively faciliate the charge transport and accommodate volume variation upon prolonged charge/discharge cycling for reversible lithium storage...
February 2015: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
Han Zhou, Lusi Zhang, Dongyang Zhang, Shuangqiang Chen, Paul R Coxon, Xiong He, Mike Coto, Hyun-Kyung Kim, Kai Xi, Shujiang Ding
We report a simple synthetic approach to coaxially grow transition metal oxide (TMO) nanostructures on carbon nanotubes (CNT) with ready control of phase and morphology. A thin (~4 nm) sulfonated-polystyrene (SPS) pre-coating is essential for the deposition of transition metal based materials. This layer has abundant sulfonic groups (-SO3 - ) that can effectively attract Ni2+ , Co2+ , Zn2+ ions through electrostatic interaction and induce them via hydrolysis, dehydration and recrystallization to form coaxial (NiO, Co3 O4 , NiCoO2 and ZnCo2 O4 ) shells and a nanosheet-like morphology around CNT...
November 25, 2016: Scientific Reports
Wei-Wei Liu, M T Jin, W M Shi, J G Deng, Woon-Ming Lau, Y N Zhang
Systematic first principles calculations were performed for ZnCo2 O4 to clarify its structural and electronic properties, and particularly the structural stability as an electrode material for lithium-ion batteries. For samples with low Li concentration, e.g., Lin ZnCo2 O4 with n < 1, Li atoms take the center of oxygen octahedra and may diffuse rapidly. Structure distortions and volume expansions can be observed in Lin ZnCo2 O4 with n > 1 and amorphous structures eventually prevail. The AIMD simulations for Li9 ZnCo2 O4 suggest the formation of Li2 O, Co3 O4 and LiZn local compounds or alloys...
November 9, 2016: Scientific Reports
In Kyu Moon, Seonno Yoon, Jungwoo Oh
To achieve high energy storage on three-dimensional (3D) structures at low cost, materials with high power and long cycle life characteristics have to be developed. We synthesized ZnCo2 O4 /reduced graphene oxide (rGO) binary composites in commercial sponges. ZnCo2 O4 nanosheets were grown on the surface of GO/sponge through a hydrothermal reaction. The resulting flexible, free-standing ZnCo2 O4 /rGO/sponge electrodes were used as the electrodes in a symmetric supercapacitor. ZnCo2 O4 /rGO/sponge electrodes have a large specific capacitance of 1116...
January 12, 2017: Chemistry: a European Journal
Hu Long, Anna Harley-Trochimczyk, Siyi Cheng, Hao Hu, Won Seok Chi, Ameya Rao, Carlo Carraro, Tielin Shi, Zirong Tang, Roya Maboudian
Nanowire-assembled 3D hierarchical ZnCo2 O4 microstructure is synthesized by a facile hydrothermal route and a subsequent annealing process. In comparison to simple nanowires, the resulting dandelion-like structure yields more open spaces between nanowires, which allow for better gas diffusion and provide more active sites for gas adsorption while maintaining good electrical conductivity. The hierarchical ZnCo2 O4 microstructure is integrated on a low-power microheater platform without using binders or conductive additives...
November 23, 2016: ACS Applied Materials & Interfaces
Shrikant S Raut, Babasaheb R Sankapal
One-step, simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method has been used to synthesize porous network of zinc cobaltite (ZnCo2O4) in 2D form on stainless steel (SS) substrate. Porous structure of ZnCo2O4 electrode enables electrochemical specific capacitance of 675Fg(-1) at 5mVs(-1) sweep rate with high rate capability and cycling performance of 69% over 2000 cycles. Furthermore, fabricated ZnCo2O4 solid-state supercapacitor cell in symmetric mode using PVA-KOH gel electrolyte exhibited a specific capacitance of 69...
February 1, 2017: Journal of Colloid and Interface Science
Fengdong Qu, Huifang Jiang, Minghui Yang
The rational design of nanoscale metal oxides with hollow structures and tunable porosity has stimulated tremendous attention due to their vital importance for practical applications. Here, we report the designed synthesis of ZnO/ZnCo2 O4 hollow core-shell nanocages (HCSNCs) through a metal-organic framework (MOF) route. The strategy includes the synthesis of a zeolite imidazolate framework-8 (ZIF-8)/Co-Zn hydroxide core-shell nanostructure precursor and subsequent transformation to ZnO/ZnCo2 O4 HCSNCs by thermal annealing of the as-prepared precursor in air...
September 15, 2016: Nanoscale
Hyung Ju Park, Jinmo Kim, Nak-Jin Choi, Hyunjoon Song, Dae-Sik Lee
Since metal oxide semiconductors were investigated as chemiresistors, rapid advances have been reported in this field. However, better performance metrics are still required, such as higher sensitivity and selectivity levels for practical applications. To improve the sensing performance, we discuss an optimal composition of the active sensing material, nonstoichiometric Co-rich ZnCo2O4, prepared by the partial substitution of Co(2+) into Zn(2+) in Co3O4 without altering a hollow sphere morphology. Remarkably, this Co-rich ZnCo2O4 phase achieved detection limits for formaldehyde as low as 13 ppb in experimental measurements and 2 ppb in theory, which were the lowest values ever reported from actual measurements at a working temperature of 225 °C...
February 10, 2016: ACS Applied Materials & Interfaces
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