JOURNAL OF ALLOYS AND COMPOUNDS
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2022
·
IF 6.371
Jianfeng Dai,Zhaokuan Li,Rui Yu,Danqiang Huang
Metal element selection and reasonable design of material morphology are essential to ensure the improvement of supercapacitor electrochemical performance. In this work, based on the cobalt salts and manganese salts in the bimetallic organic framework with different molar ratios, a ternary layered double hydroxide electrode material with a hollow polyhedral structure was made by Ni 2+ etching the bimetallic organic framework to assess its suitability for use in a supercapacitor. When the molar ratio of Co/Mn is 3:1, NiCoMn-LDH 3:1 has a maximum specific capacity of 227.8 mAh g −1 at the current density of 1 A g −1 and a capacity retention rate after 1500 cycles is 83.9% at the large current density of 10 A g −1 . Additionally, an asymmetric supercapacitor was assembled with NiCoMn LDH 3:1 as the positive electrode and AC as the negative electrode. The prepared NiCoMn-LDH 3:1//AC ASC device showed a high energy density of 64.3 Wh kg −1 at 799.9 W kg −1 . Meanwhile, NiCoMn-LDH 3:1//AC ASC devices have excellent cycle stability, with a capacitance retention rate of 85.1% of the initial capacity after 5000 cycles at a high current density of 10 A g −1 . This work provides a new idea for the development of supercapacitor materials .
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JOURNAL OF ELECTROANALYTICAL CHEMISTRY
·
2022
·
IF 4.598
Jiamin Zou,Jin Zou,Wei Zhong,Qian Liu,Xigen Huang,Yansha Gao,Limin Lu,Shuwu Liu
Layered double hydroxide (LDH) is supposed to be ideal capacitive materials owing to its excellent theoretical specific capacitance. Nevertheless, the inherent defects of LDH such as unstable structure, and agglomerations along with poor conductivity, lead to low rate-capability and poor cycle stability. In this work, poly(3,4-ethylenedioxythiophene) (PEDOT)@nickel–cobalt LDH on carbon cloth (PEDOT@NiCo-LDH/CC) was proposed as a highly capacity electrode material for supercapacitors. Herein, hollow NiCo-LDH nanocage was firstly assembled by NiCo-LDH nanosheets on CC (NiCo-LDH/CC) via an in-situ transformations of ZIF-67, subsequent by coating PEDOT network (PEDOT@NiCo-LDH/CC) on NiCo-LDH/CC via an electrodeposition process. The unique hollow nanocage structure can effectively restrain agglomeration of the LDH nanosheets. Besides, the introduction of PEDOT not only remarkable improves the conductivity, but also protects those hollow LDH nanocages from destruction during the cycling process. Consequently, the PEDOT@NiCo-LDH/CC electrode manifests outstanding capacitance properties of 1508F/g at 1 A/g, excellent rate capability of 71.9 % capacitance retention in 1–20 A/g, and remarkable cycling life of 90.1 % capacity retention at 20 A/g after 10,000 cycles. Moreover, a hybrid asymmetric supercapacitor (ASC) device was assembled by using PEDOT@NiCo-LDH/CC// activated carbon. Such ASC reveals a prominent energy density of 77.1 Wh kg −1 under the power density of 750 W kg −1 . This project provides new inspirations into the rational design of high-performance electrode material in application of energy storage.
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PROGRESS IN ORGANIC COATINGS
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2022
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IF 6.206
Qi Guo,Tengle Wang,Tian C. Zhang,Like Ouyang,Shaojun Yuan
The practical applications of magnesium alloys are significantly limited owing to being susceptible to corrosion. In this study, superhydrophobic double layered MgAl-LDH/epoxy (DMALE) composite coatings were fabricated on magnesium alloys by the combination of hydrothermal synthesis and spraying methods, which consisted of a bottom layer of MgAl-LDH(WO 4 2− )/epoxy coating and a top layer of superhydrophobic hexadecyltrimethoxysilane (HDTMS)-modified MgAl-LDH(CO 3 2− )/epoxy coating. The as-prepared DMALE coating delivered superior superhydrophobic and self-cleaning property. Such composite coating was demonstrated to possess good anticorrosion property, good chemical stability, and high abrasion resistance. This large-scale prepared composite coating is potentially useful for corrosion protection of magnesium alloys.
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DALTON TRANSACTIONS
·
2022
·Vol. 51
·期 36
·13970-13977
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IF 4.569
Xiaoman Hou,Jing Li,Jian Zheng,Luming Li,Wei Chu
The transition metal hydroxide NiFe LDH is a promising oxygen evolution reaction (OER) catalyst. Surface engineering, such as the introduction of oxygen vacancies into NiFe LDH, has been reported to further improve the OER performance; however, searching a facile approach remains an issue. In this work, we report a novel and efficient electrochemical reduction method for in situ introduction of oxygen vacancies into NiFe LDH laminates by applying a constant negative voltage. The results show that the reduced NiFe LDH (denoted as r-NiFe LDH) exhibits enhanced OER performance versus its counterpart NiFe due to the increase of oxygen vacancy density, the electrochemically active surface area, wetting ability, and the significant electron transfer rate. In 1 M KOH, the r-NiFe LDH shows a high current density of 110 mA cm−2 at 1.60 V (vs. RHE), which is 2.8 times the current density of NiFe LDH (40 mA cm−2), as well as the long-term stability of 100 h. This electroreduction method is also applicable to other LDH materials loaded by different current substrates or synthesized by various methods, demonstrating its universality for the enhancement of the OER activity of LDH electrocatalysts.
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Nanomaterials
·
2022
·Vol. 12
·期 15
·2640
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IF 5.719
Liming Yang,Tao Yang,Yafeng Chen,Yapeng Zheng,Enhui Wang,Zhentao Du,Kuo-Chih Chou,Xinmei Hou
The development of bifunctional electrocatalysts with efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is still a key challenge at the current stage. Herein, FeNi LDH/V2CTx/nickel foam (NF) self-supported bifunctional electrode was prepared via deposition of FeNi LDH on V2CTx/NF substrate by hydrothermal method. Strong interfacial interaction between V2CTx/NF and FeNi LDH effectively prevented the aggregation of FeNi LDH, thus exposing more catalytic active sites, which improved electrical conductivity of the nanohybrids and structural stability. The results indicated that the prepared FeNi LDH/V2CTx/NF required 222 mV and 151 mV overpotential for OER and HER in 1 M KOH to provide 10 mA cm−2, respectively. Besides, the FeNi LDH/V2CTx/NF electrocatalysts were applied to overall water splitting, which achieved a current density of 10 mA cm−2at 1.74 V. This work provides ideas for improving the electrocatalytic performance of electrocatalysts through simple synthesis strategies, structural adjustment, use of conductive substrates and formation of hierarchical structures.Keywords:V2CTxMXene;layered double hydroxide;nanohybrids;overall water splitting
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Catalysis Science & Technology
·
2021
·Vol. 11
·期 23
·7727-7739
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IF 6.119
Biao Zhu,Qianxin Xu,Xiaoyan Bao,Dawei Lu,Hao Yin,Yumei Qin,Xing-Can Shen
The development of efficient and stable photocatalysts to solve environmental issues is essential and remains a big challenge. In this work, flower-like CoNiFe-LDH is deposited in situ on g-C3N4 nanosheets, successfully constructing a Z-scheme heterojunction CoNiFe-LDH/g-C3N4 photocatalyst for the photoreduction of CO2 and photodegradation of MB dye. The synthesized nanohybrid shows superior photocatalytic CO2 performance (42.04 μmol g−1 h−1) and fast photodegradation MB performance (0.1057 min−1). The improved photocatalytic performance was attributed to the formation of the Z-scheme heterojunction with matched energy bands, and the intimate heterojunction contact interface, which significantly enhanced the interfacial charge transfer rate and improved the separation efficiency of electron–hole pairs. Moreover, the photocatalytic mechanism was proposed based on PL, photocurrent responses, EIS, and EPR experiments. This work can shed light on further application for environmental problems of Z-scheme heterojunction photocatalysts.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2020
·
IF 7.489
Junnan Tao,Xiaohui Yu,Qinqin Liu,Guiwu Liu,Hua Tang
The requisite interfacial contact of heterojunction photocatalysts has a significant contribution in separation of interfacial charge carriers for photocatalytic hydrogen (H 2 ) evolution in a more efficient manner. Herein, an internal electric field (IEF)-induced S–scheme system comprised of two-dimensional (2D) CoAl layered double hydroxide (LDH) and 2D molybdenum disulfide (MoS 2 ) was constructed via a simple hydrothermal process. In the presence of visible-light irradiation, the 2D/2D MoS 2 /CoAl LDH hybrid demonstrates eightfold greater photocatalytic H 2 generation rate as compared with that of CoAl LDH. The mechanism was investigated in the light of the results of the X-ray photoelectron spectroscopy (XPS) and work-function calculated by density functional theory (DFT) simulation, and the improved activity was ascribed to that the rapid detachment of the electron-hole (e − -h + ) combinations and high redox ability, both are simultaneously realized in MoS 2 /CoAl LDH hybrid with a 2D/2D S–scheme charge transfer mechanism induced by the IEF across interface of the MoS 2 and CoAl LDH. Furthermore, favorable 2D/2D structure and better H* adsorption behavior of MoS 2 /CoAl LDH also promoted the improvement of water reduction performance. This work is a valuable guideline in developing of IEF-induced S–scheme photocatalysts with 2D/2D architecture for improved photocatalytic performance.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
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2020
·
IF 4.939
Xinzhu Wen
It is crucial for the storage and conversion of hydrogen energy to substitute the low theoretical potential of urea oxidation reaction (UOR) for the high theoretical potential of anodic water electrolysis (oxygen evolution reaction (OER)). In this paper, it puts forward a brief and scalable strategy, so as to synthesize a novel bifunctional nickel-iron layered double hydroxide and multi-walled carbon nanotube composites supported on Ni foam, represented as NiFe-LDH/MWCNTs/NF. Electrochemical measurements demonstrate that NiFe-LDH/MWCNTs/NF is able to realize an efficient electrocatalysis for UOR. During this process, merely a potential of 1.335 V is needed at 10 mA cm −2 , which can be taken to replace OER, thus reducing overpotential in H 2 -production as well as power consumption . In addition, NiFe-LDH/MWCNTs/NF also exhibits electro-defense electrocatalytic efficiency to achieve the reaction of hydrogen evolving process, which provides a low overpotential of 98 mV at 10 mA cm −2 . To further prove it, all-water-urea electrolysis measurement is carried out in 1 M KOH and 0.5 M Urea with NiFe-LDH/MWCNTs/NF as cathode and anode respectively. NiFe-LDH/MWCNTs/NF||NiFe-LDH/MWCNTs/NF electrode manages to provide 10 mA cm −2 at a voltage of merely 1.507 V, 156 mV lower than that of water splitting, which proves its commercial viability in energy-saving hydrogen production .
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ACS Applied Materials & Interfaces
·
2020
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IF 8.758
Tailong Cai,Ping Zhang,Xiaoyuan Shen,Erzhuo Huang,Xiaoping Shen,Jiangtao Shi,Zhe Wang,Qingfeng Sun
Traditional methods of removing gaseous formaldehyde are often associated with high energy consumption and secondary pollution. In this study, a new wood veneer-based composite decorated with Pt-loaded NiFe-LDH nanosheets is successfully developed by a hydrothermal reaction and impregnation-chemical reduction. NiFe-LDH nanosheets as an adsorbent can capture formaldehyde molecules through their abundant hydroxyl groups. Pt nanoparticles as catalytic centers are evenly distributed on the surface of NiFe-LDH to excite the O atoms linked to NiFe-LDH and absorbed oxygen, which will further attack the absorbed formaldehyde molecules to generate CO2 and H2O. And the wood veneer not only increases the active area of the catalyst by endowing it with good dispersion but also provides convenient channels for reactants and products. In a simulated dark environment at room temperature, this synthetic wood veneer-based composite exhibits admirable catalytic activity, which can effectively degrade almost all gaseous formaldehyde with the initial concentration of 0.2 mg m–3 in 30 min and maintain a high catalytic activity of ≥97% after 10 cycles. This paper presents a feasible strategy for synthesizing an energy-efficient and ecofriendly wood veneer-based composite for efficient gaseous formaldehyde degradation at room temperature, which may play an important role in indoor air purification as a promising decorative material.
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Nano Research
·
2019
·Vol. 13
·期 1
·79-85
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IF 8.515
Wang Tian-Jiao,Liu Xiaoyang,Li Ying,Li Fumin,Deng Ziwei,Chen Yu
Electrochemical water splitting (EWS) is a highly clean and efficient method for high-purity hydrogen production. Unfortunately, EWS suffers from the sluggish and complex oxygen evolution reaction (OER) kinetics at anode. At present, the efficient, stable, and low-cost non-precious metal based OER electrocatalyst is still a great and long-term challenge for the future industrial application of EWS technology. Herein, we develop a simple and fast approach for gram-scale synthesis of flower-like cobalt-based layered double hydroxides nanosheet aggregates by ultrasonic synthesis, which show outstanding electrocatalytic performance for the oxygen evolution reaction in alkaline media, such as preeminent stability, small overpotential of 300 mV at 10 mA·cm −2 and small Tafel slope of 110 mV·dec −1 .
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JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2020
·Vol. 167
·期 2
·024501
·
IF 3.721
Xue Li,Mingli Fan,Danan Wei,Xiaolong Wang,Yinling Wang
Highly efficient and low-cost oxygen evolution reaction (OER) electrocatalysts have been urgently needed for the development of renewable hydrogen energy via water electrolysis. Herein, a core-shell NiO nanoparticles decorated carbon sphere (NiO/C) and NiFe-layered double hydroxide (NiFe-LDH) nanocomposite (NiO/C@NiFe-LDH) was prepared by a calcination-hydrothermal synthesis approach. In this nanocomposite, NiO/C as the core were derived from Ni based metal organic frameworks (Ni-MOFs), which not only provide a porous and conductive carbon support for NiFe-LDH nanosheets to expose active sites, but also offer a synergistic active site for NiFe-LDH nanosheets. The structure and morphology of NiO/C@NiFe-LDH were mainly characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption-desorption test. The OER catalytic activity of NiO/C@NiFe-LDH was optimized by adjusting the ratio between NiO/C and NiFe-LDH and adding bridging agents. Under the optimum conditions, the overpotential at 10 mA cm−2 for NiO/C@NiFe-LDHs is only 299 mV(vs RHE), lower than that of commercial RuO2 (330 mV). Besides, the NiO/C@NiFe-LDH exhibits a good stability in 10-hour testing. These results show that the ingenious combination of different OER catalysts may be an effective strategy to prepare low-cost OER catalysts with good performance.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2019
·
IF 6.361
Chunyu Qiu,Fuxian Cai,Yuan Wang,Yijun Liu,Qingxiang Wang,Chuan Zhao
It is a highly desired yet challenging task to replace rare and expensive noble metal catalysts with inexpensive and earth-abundant metal ones in electrochemical sustainable chemistry field. Herein, the bimetallic zinc-cobalt layered double hydroxide nanosheets (ZnCo-LDH NS) have been facilely synthesized using 2-methylimidazole as a bifunctional alkali source (OH − ) and a morphological controlling reagent by the one-step room-temperature reaction. The mechanism study shows that the weak organic base of 2-methylimidazole-induced slow release of OH − in water/ethanol is the controlling factor for the formation of the LDH nanosheets. The ZnCo-LDH NS modified on glassy carbon electrode exhibited an overpotential of 385 mV at 10 mA cm −2 and a Tafel slope of 108 mV dec −1 in 1.0 M KOH for oxygen evolution reaction , outperforming the corresponding the monometal oxides of Zn-OH, Co-OH, the NaOH produced ZnCo-LDH microparticles , and even the benchmark catalyst of RuO 2 at high current density. Characterization experiments indicated that the outstanding electrocatalytic activity can be ascribed to the nanosheet-induced surface area effect, excellent electronic conductivity, and the coupling effect between Zn 2+ and Co 2+ in the material. This work offers a facile and environmental-friendly method for synthesising LDH nanosheets bearing enhanced oxygen evolution reaction activity.
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