JOURNAL OF ELECTROANALYTICAL CHEMISTRY
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2023
·
IF 4.5
Zhihao Song,Qingkun Meng,Fuxiang Wei,Qing Yin,Yanwei Sui,Jiqiu Qi
Cobalt-based metal–organic framework (MOF) is commonly used as templates to prepare layered double hydroxides (LDHs) with specific morphology to improve the pseudocapacitance capacity. A multi-step synthesis method was employed in the reported work to introduce a second metal during the preparation process of bimetallic LDH materials. Herein, we disclosed a facile and efficient one-step in-situ hydrolysis strategy to prepare CoNi-LDH under mild condition using CoNi-MOF precursor, which introduces Ni element in the Co-MOF nucleation process. The method for synthesizing CoNi-LDH with nanoflower structure can omit the past time-consuming synthesis process and the complex modification process. The obtained CoNi-LDH at 60 °C achieves specific capacitance as high as 1634.1F g −1 at a current density of 1 A g −1 . The assembled CoNi-LDH-24//RGO ASC deliver high energy density of 48.97 Wh kg −1 at the power density of 787.16 W kg −1 , and the capacitance retention after 10,000 cycles can reach 81.7%. This work provides a mild and simple method to synthesize 3D structure LDH materials with excellent supercapacitor performance, and further confirms that the in-situ hydrolysis method is feasible and promising in the preparation of 3D CoNi-LDH nanoflowers.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2023
·
IF 6.2
Shucheng Liu,Ming Li,Yi Tang,Xiaogang Wen
A novel Fe 3 O 4 /MgAl-TA LDH (FTLDH) nanocomposites with tartrate anion-intercalation is successfully synthesized by a one-step hydrothermal process. The synthesized FTLDH are flower-like hollow microspheres composed of nanosheets with an average thickness of 25 nm. The specific surface area of the calcined FTLDH (FTLDH-C) greatly increases to 120 m 2 /g, exposing more adsorption sites which can bind the target adsorbates. The adsorption capacities of obtained hollow microspheres towards Congo Red (CR), Malachite Green (MG) and Neutral Red (NR) can reach 1520, 819 and 929 mg/g at room temperature, 2590, 1041 and 1153 mg/g at 45 °C, receptively. The excellent dye adsorption performance can be attributed to the unique hollow and porous microstructure, trumpet-shaped through channels in shell layer and high specific surface area. The dye adsorption process on FTLDH-C hollow microsphere is in accordance with Langmuir isotherm and pseudo-second-order kinetic models. The adsorption is mainly driven by electrostatic attraction (CR) and the hydrogen bonds/π-π conjugation etc. chemical interaction (CR, MG, NR etc.) between dye molecules and LDH nanoflakes. Due to the presence of magnetic Fe 3 O 4 nanoparticles in the nanocomposites, the used adsorbent can be easily recollected with magnetic field. This study puts forward a new way to develop high-performance adsorbent via microstrucure-design and magnetic functionalization.
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Catalysts
·
2023
·Vol. 13
·期 1
·198
·
IF 3.9
Xiaohu Xu,Xinyue Yu,Kaiwei Guo,Lijuan Dong,Xiangyang Miao
The search for low-cost, high-performance, and robust stability bifunctional electrocatalysts to substitute noble metals-based counterparts for overall water splitting to generate clean and sustainable hydrogen energy is of great significance and challenges. Herein, a high-efficient bi-functional nickel–iron phosphide on NiFe alloy foam (denoted as e-NFP/NFF) with 3D coral-like nanostructure was controllably constructed by means of alkali etching and the introduction of non-metallic atoms P. The unique superhydrophilic coral-like structure can not only effectively facilitate the exposure of catalytic active sites and increase the electroactive surface area, but also accelerate charge transport and bubble release. Furthermore, owing to the synergistic effect between the bicomponent of nickel–iron phosphides as well as the strong electronic interactions of the multiple metal sites, the as-fabricated catalyst behaves with excellent bifunctional performance for the hydrogen evolution reaction (overpotentials of 132 and 286 mV at 10 and 300 mA·cm−2, respectively) and oxygen evolution reaction (overpotentials of 181 and 303 mV at 10 and 300 mA·cm−2, respectively) in alkaline electrolytes. Impressively, cells with integrated e-NFP/NFF electrodes as a cathode and anode require only a low cell voltage (1.58 V) to drive a current density of 10 mA·cm−2for overall water splitting, along with remarkable stability in long-term electrochemical durability tests. This study provides a tunable synthetic strategy for the development of efficient and durable non-noble metal bifunctional catalysts based on the construction of an elaborate structure framework and rational design of the electronic structure.Keywords:overall water splitting;transition metal phosphide;alkaline etching;hydrogen evolution reaction;oxygen evolution reaction
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DALTON TRANSACTIONS
·
2023
·Vol. 52
·期 34
·12038-12048
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IF 4
Lu Wang,Yi Liu,Xiaoheng Liu,Wei Chen
Powder electrocatalysts for oxygen evolution reactions usually need adhesives for electrocatalytic performance tests, leading to the increase of resistance, reduction of catalyst loading, and easy stripping of the catalyst under long-time or high current operation. In this study, Ce-doped CoFe layered double hydroxides were uniformly grown on nickel foam by a one-step hydrothermal route. A nanostructured self-supported electrode Ce-CoFe-LDH/NF without adhesive was obtained directly, which has a regular nanoneedle morphology with a length of ∼1.2 μm and tip width of ∼20 nm. Adopting Ce3+ ions with a large radius to partially displace Fe3+ ions with a small radius produced lattice distortion and more defects in the host layer of CoFe-LDH, whereby possessing the great potential to enhance catalytic behaviors. Once used as an electrocatalyst for the oxygen evolution reaction, Ce-CoFe-LDH/NF shows an outstanding electrocatalytic performance, including an optimized overpotential of 225 mV at 10 mA cm−2, a decreased Tafel slope of 34.34 mV dec−1, and a low charge transfer impedance of 2.4 Ω in 1 M KOH electrolyte. Moreover, the overpotential of the working electrode increased by only 0.04 V after 24 hours and was maintained at a current density of 50 mA cm−2. These results demonstrate a low-cost strategy compared to using noble metal OER electrocatalysts. Thus, this study highlights a ready universal approach to fabricate high-performance supported catalysts for energy-related applications.
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ENVIRONMENTAL RESEARCH
·
2022
·
IF 8.431
Shuoqi Ren,Yuchen Wang,Zijian Han,Qiwei Zhang,Chongwei Cui
A highly efficient absorbent was developed in this study by modifying polydopamine film on Mg–Al layered double hydroxide (PDA/MgAl-LDH) to remove Cr(VI) from wastewater. The characterization results showed that the polydopamine film was successfully coated on the MgAl-LDH surface. The preparation ratio, pH, and adsorbent dosage influencing absorption by PDA/MgAl-LDH were systematically investigated. The absorption capacity of Cr(VI) by PDA/MgAl-LDH was 87 mg/g. The equilibrium adsorption isotherm of PDA/MgAl-LDH was in good agreement with that of the Langmuir model. Therefore, the pseudo-second-order kinetic model is suitable for describing adsorption kinetics. The interaction between PDA and Cr(VI) and Cr(III) was investigated using density generalized function theory (DFT), which demonstrated that the PDA amino group could provide electrons for Cr(VI) reduction. Hydrogen and covalent bonding were dominant during the chemisorption process of PDA absorbing Cr(VI), the nitrogen of 5,6-dihydroxyindole was the primary active site for absorbing Cr(III), and electrostatic attraction was mainly responsible for Cr(III) absorption. Therefore, PDA/MgAl-LDH has the potential to adsorb and remove Cr(VI) from wastewater.
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FUEL PROCESSING TECHNOLOGY
·
2022
·
IF 8.129
Hao Zhu,Fei Wang,Jianchun Jiang,Zeng Zhang,Yuchan Du,Junfeng Feng,Xiaoxiang Jiang
In order to deal with the deficiency of active sites in Ni catalyst, Ni Fe nanosheet (Ni-Fe/Al 2 O 3 -NS) catalyst was synthesized by using Ni-Fe-Al LDH as the precursor. The catalyst was further utilized in the lipid hydrotreatment for green diesel production. With a lamellar structure and large Ni loading (more than 60%), the Ni-Fe/Al 2 O 3 -NS catalyst possessed abundant Ni sties with high dispersion, large surface area, and strong acidity. Moreover, in Ni-Fe/Al 2 O 3 -NS the highly active Ni 3 Fe phase was formed, which promoted the decarbonylation route in hydrotreatment. The Ni-Fe/Al 2 O 3 -NS catalyst achieved 98.7% conversion with 98.1% alkane yield in oleic acid hydrotreatment under very mild conditions (220 °C, 2 MPa of hydrogen pressure, 3 h). The catalytic performance of Ni-Fe/Al 2 O 3 -NS was much higher than traditional Ni-Fe/Al 2 O 3 and other catalysts reported in current related studies.
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APPLIED CLAY SCIENCE
·
2022
·
IF 5.907
Kecan Zhang,Jing Li,Liang He,Qingqing Guan,Ximeng Xu,Rongrong Miao,Minli Wang,Huajing Zhou
Layered double hydroxides (LDH) was proved as preferable retardants for lignocellulosic materials . In this study, Mg/Al-LDH was selected and one-step modified by GP which exhibited superior characteristics of flame retardancy and non-toxicity. Results showed that more complete two-dimensional layered structure with suitable crystal particle size was formed for GP modified LDH. Specifically, GP 3 -LDH not only enhanced the thermal stability of cellulosic composites, but also assisted the peak heat release rate (PHRR) and total heat release (THR) in declining 42.5% and 22.7% compared with those added with non-modified Mg/Al-LDH. In addition, the limiting oxygen index (LOI) achieved as high as 27.7% with 15 wt% addition, indicating the successful modification with GP for outstanding flame-retardant performance, low addition and controlled strength of cellulosic composites.
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APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Li Wang,Junli Wang,Xuanbing Wang,Min Li,Jinlong Wei,Nianxiang Hu,Ruidong Xu,Linjing Yang
Low-cost and high-efficiency electrocatalysts produced by constructing the interfacial heterostructure have attracted more attention in oxygen evolution reaction (OER). Herein, we synthesize a three-dimensional (3D) heterogeneous structure of Ni x Co y Se 2 nanospheres loaded onto NiFe hydroxide (NiFe-LDH) nanosheets via bare nickel foam (NF) two-step electrodeposition. The optimal NiFe-LDH@Ni x Co y Se 2 /NF nanosheets heterojunction electrocatalyst is verified with an excellent OER performance in 1.0 M KOH solution, which only requires a low overpotential of 265.5 mV and 297.8 mV to drive high current density of 100 mA cm −2 and 500 mA cm −2 , respectively, long-term durability of more than 60 h at 100 mA cm −2 , and an extremely low Tafel slope of 57.5 mV dec −1 . Meanwhile, due to the dramatic improvement in OER performance, there is an enhancement in the overall water-splitting activity of the NiFe-LDH@Ni x Co y Se 2 /NF nanosheets heterojunction, attaining a current density of 20 mA cm −2 at the low cell voltage of 1.65 V. As a result, it shows the importance of constructing highly efficient OER catalyst with the rational design of heterostructures. The enhanced catalytic performance can be attributed to the large exposed electrocatalytic active sites accessible and constructed an efficient electronic transmission channel by eliminating contact resistance.
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ANALYTICA CHIMICA ACTA
·
2022
·
IF 6.911
Tianze Cong,Yifeng Zhang,Hui Huang,Yongpeng Zhao,Chengwei Li,Zeng Fan,Lujun Pan
The sensitivity of surface enhanced Raman spectroscopy (SERS) depends on the construction of “hot spots” and the number of analyte molecules adsorbed onto the substrates. Herein, we have constructed a kind of SERS substrate based on gold nanostars (Au NSs) coated with nickel-cobalt layered double hydroxide (LDH) using a zeolitic imidazolate skeleton as sacrificial template via nickel ions etching. LDH was used as the absorption medium for target molecules, and concurrently prevented Au NSs from agglomeration to improve stability and uniformity of the substrate. Meanwhile, encapsulated Au NSs were used as the enhancement medium for Raman detection. The porous LDH shell around the Au NSs promoted the target molecules to approach the Au NSs, which was certified by the experimental results of UV–Vis absorption and simulation analysis using the density functional theory . The detection of Rhodamine 6G solution with a concentration of 10 −9 M was realized by the AuNS/LDH, and the relative standard deviation of Raman signals was less than 10%. Therefore, this work provides a new idea and a suitable structure to improve SERS signal intensity by introducing adsorption medium into the SERS substrate.
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CRYSTENGCOMM
·
2021
·Vol. 24
·期 6
·1189-1194
·
IF 3.545
Mengya Yang,Rong Zhao,Yi Liu,Hua Lin
In this work, a highly efficient electrocatalyst Fe-Ni2P/N-GO with hierarchical structure was developed through phosphating NiFe-based layered double hydroxide (LDH) supported by N-doped graphene oxide (GO), which was assembled by a solvothermal method. The LDH-derived Fe-Ni2P/N-GO composites were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). Electrochemical measurements show that Fe-Ni2P/N-GO has excellent oxygen evolution reaction (OER) performance with an overpotential of 269 mV at a current density of 10 mA cm−2 and a Tafel slope of only 72 mV dec−1. Besides, the composite exhibits a minimum charge transfer resistance compared with Fe-Ni2P and Fe-Ni2P/GO, and high long-term stability in alkaline solution.
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RSC Advances
·
2023
·Vol. 13
·期 42
·29695-29705
·
IF 3.9
Hui Fui,Shumin Gao,Xinran Ma,Yiping Huang
Layered double hydroxides (LDHs) have been extensively investigated as promising peroxymonosulfate (PMS) activators for the degradation of organic pollutants. However, bulk LDHs synthesized using conventional methods possess a closely stacked layered structure, which seriously blocks active sites and yields low intrinsic activity. In this study, we exfoliated bulk CoAl-LDHs to fabricate CoAl-LDH nanosheets by alkali-etching and Ostwald ripening via a simple hydrothermal process in a KOH solution. The exfoliated LDHs possessed the typical nanosheet structure with more exposed active sites for PMS activation, and hence, boosted the degradation of the pollutants. CoAl-1 exhibited an outstanding catalytic performance as the PMS activator for rhodamine B (RhB) degradation with the apparent rate constant of 0.1687 min−1, which was about 3.63 and 5.02 times higher than that of commercial nano-Co3O4 and bulk CoAl-LDH, respectively. The maximum RhB degradation of 93.1% was achieved at the optimal reaction conditions: catalyst dose 0.1 g L−1, PMS concentration 0.3 mM, pH 7, and temperature 298 K. Further analysis of RhB degradation mechanism illustrated that singlet oxygen (1O2) dominated RhB degradation in the CoAl-1/PMS system, while ˙OH, ˙O2−, and ˙SO4− may mainly serve as the intermediates for the generation of 1O2 and were indirectly involved in the degradation. This study provides a promising strategy for developing two-dimensional LDH nanosheets for wastewater remediation.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Qi Chen,Hui Pan,Zhixin Chen,Xueliang Jiang,Yao Li,Wensheng Tian,Hao Liu,Shenmin Zhu
Transition metal layered double hydroxides have extremely high specific capacitances but suffer from poor rate performance and cycling stability due to their low conductivity and structural stability . In this study, cobalt-coordinated carbon quantum dots (CoCQDs) were designed and synthesized to enhance the energy storage performance of nickel–cobalt layered double hydroxides (NiCo-LDH). Nickel and cobalt ions were co-electrodeposited with the CoCQDs to form a NiCo-LDH based composite electrode (denoted as CoC@LDH). Since the CoCQDs participated in the formation of the NiCo-LDH, the carbon quantum dots could be strongly bonded to the NiCo-LDH nanosheets through coordination interactions. Thus, the conductivity as well as the structure stability of the NiCo-LDH was effectively improved, which greatly boosted the cycle stability and rate performance of the NiCo-LDH. Several CoCQDs with different Co contents ( n CoCQDs, n = 0.5, 1.0, 2.0) were fabricated and their effects on the performance of the resultant electrodes n CoC@LDH were investigated. The 1.0CoC@LDH electrode exhibited an impressive specific capacitance of 1867 F g –1 at 1 A-g –1 , along with a significantly enhanced capacitance retention of 84.6 % after 6000 cycles at 5 A g –1 (benchmark 49.5 %). This ingenious design provides a new avenue for fabricating pseudo-capacitive materials with unprecedented high performance.
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