CHEMISTRY-A EUROPEAN JOURNAL
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2021
·Vol. 27
·期 42
·10966-10972
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IF 5.236
Lanqing Li,Wei Gao,Min Lei,Dan Wen
Graphical A simple ex situ wet chemical transformation method of alkali treatment was proposed to prepare Ni(OH) 2 nanostructured flowers with large specific surface areas from Ni-MOF-74. The relationship between concentration of alkali and the structure properties of corresponding Ni(OH) 2 was uncovered. As the results, the catalyst of Ni(OH) 2 -0.25 performed remarkably catalytic properties with lower potential, higher current density and excellent durability towards MOR among various samples. Post treatment of metal-organic frameworks (MOFs) is widely employed to develop efficient electrocatalysts with better catalytic properties. But the complex processes of post treatment generally led to the collapse of the original structures of MOFs, making the preservation of their pristine hierarchical porous structure a great challenge. Herein, we propose the strategy of alkali treatment of Ni-MOF to transform it into Ni(OH) 2 with similar morphology and enhanced electrocatalytic properties for methanol oxidation reaction (MOR). The structure and electrocatalytic properties of as-obtained Ni(OH) 2 nanostructured flowers were seriously depended on the alkali concentrations. As the result, Ni(OH) 2 obtained from Ni-MOF treated by 0.25 M NaOH (noted as Ni(OH) 2 -0.25) performs 1.5 and 2.5 times larger current density than those of Ni(OH) 2 -0.025 and Ni(OH) 2 -0.5 for MOR. Moreover, the electrocatalytic process and mechanism of MOR on the catalyst of Ni(OH) 2 -0.25 are also revealed. Hence, this ex situ conversion strategy of alkali treatment for Ni-MOF uncovered the transformation of MOFs in alkaline solution and develops robust electrocatalyst for practical application of methanol fuel cells.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
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2020
·Vol. 31
·期 22
·19931-19942
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IF 2.22
Chen Qi-Wen,Zhou Jian-Ping,Zhu Pan-Pan
Mg 7 V 4 O 16 (OH) 2 ·H 2 O was prepared by improving the hydrothermal conditions and Mg 3 (VO 4 ) 2 was obtained by heat treatment of Mg 7 V 4 O 16 (OH) 2 ·H 2 O at 700 °C. XRD shows a phase transition from a hexagonal structure to an orthogonal structure, which is confirmed by the HRTEM results. Mg 3 (VO 4 ) 2 keeps overall pencil-shaped SEM morphology with Mg 7 V 4 O 16 (OH) 2 ·H 2 O but shows a lot of spaces due to the loss of hydroxyl groups and crystal water in the structure during heat treatment. Mg 3 (VO 4 ) 2 enjoys a narrower band gap in comparison with Mg 7 V 4 O 16 (OH) 2 ·H 2 O. The space in Mg 3 (VO 4 ) 2 microstructure and its narrower band gap improve the transmission efficiency of Li + , reaching a stabile capacity of 151 mAh/g after cycling 100 times at a current density of 100 mA/g.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2020
·
IF 16.683
Yiwen Huang,Guijuan Wei,Jia He,Cuihua An,Min Hu,Miao Shu,Junfa Zhu,Shuang Yao,Wei Xi,Rui Si,Zhi-Ming Zhang,Changhua An
The exploration of highly-efficient oxygen evolution reaction (OER) electrocatalyst with well-defined structure to understand specific structure-performance relationship is crucial to meet the requirement of water-splitting. Herein, we firstly used atomically dispersed IrCl x to uniformly decorate ultrathin Co(OH) 2 nanosheets to dramatically improve electrocatalytic activity. The synthesized IrCl x -Co(OH) 2 nanosheets/carbon nanotubes (CNTs) exhibits an overpotential of 230 mV to reach 10 mA/cm 2 , which was much enhanced compared to that of pristine Co(OH) 2 /CNTs (308 mV) and commercial benchmark IrO 2 (309 mV). X-ray absorption fine structure and density functional theory simulations demonstrate strong interfacial interaction between IrCl x and Co(OH) 2 nanosheets via the Cl-Ir-O and Ir-Cl-Co bond can efficiently boost its electronic conductivity. The accelerated charge transfer promotes the formation of more positively charged O atoms around cobalt centers, which is beneficial for the deprotonation on IrCl x -Co(OH) 2 and makes the catalyst facilitate OER.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2020
·
IF 7.489
Jiuli Chang,Liming Chen,Shiqi Zang,Yifan Wang,Dapeng Wu,Fang Xu,Kai Jiang,Zhiyong Gao
A facile and efficient oxygen evolution reaction (OER) catalytic system was constructed based on interconnected Ni(OH) 2 nanosheets arrays electrode and Fe(III) containing alkali electrolyte. The partial deposition of Fe(III) onto Ni(OH) 2 with heterostructure obviously enhanced the OER current density and reduced the overpotential, and the Fe(III) cations in electrolyte also furnished positive contribution to the catalytic reaction, the synergy between Ni(OH) 2 electrode and Fe(III) cations in electrolyte therefore substantially improved the OER catalytic efficiency with low overpotential (285 mV at current density of 50 mA cm −2 ) and obviously enhanced current density (391 mA cm −2 at 1.8 V). The current work expands our understanding on the effect of Fe(III) cations in electrolyte to OER efficiency of Ni based catalyst, and opens up a cost-effective and practical avenue to enhance the OER catalytic efficiency by introducing metal cations in alkali electrolyte.
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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2020
·
IF 4.939
Hongtao Zou,Feng Guo,Minghong Luo,Qilu Yao,Zhang-Hui Lu
Ultrafine NiFe nanoparticles (NPs) decorated by La(OH) 3 have been successfully prepared via a facile one-step co-reduction method without the help of surfactant or support. It was found that after being decorated with La(OH) 3 , the NiFe–La(OH) 3 NPs have a smaller particle size and lower crystallinity . The resultant NiFe–La(OH) 3 nanocatalyst exhibits an excellent catalytic activity , 100% H 2 selectivity, and satisfied recyclability for hydrogen evolution from hydrous hydrazine (N 2 H 4 ·H 2 O) at 343 K under alkaline conditions, giving a high turnover frequency (TOF) value of 100.6 h −1 , which is more than 35 times higher than pure NiFe NPs (2.8 h −1 ). The kinetics study shows that with respect to the concentration of catalyst and N 2 H 4 , the N 2 H 4 dehydrogenation reaction follows fist-order kinetics and zero-order kinetics, respectively. Furthermore, NiFe–La(OH) 3 also exhibits an outstanding performance and excellent recycle stability during high dehydrogenation of hydrazine borane (N 2 H 4 BH 3 ). The excellent performances for the dehydrogenation of N 2 H 4 and N 2 H 4 BH 3 could be attributed to the strong interaction between La(OH) 3 and NiFe NPs, as well as ultrafine and low crystalline NiFe NPs due to the addition of La(OH) 3 .
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JOURNAL OF ALLOYS AND COMPOUNDS
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2020
·
IF 4.65
Nihad Ibrahim Mohammed Abdallah,Yan Li,Xiao-Tian Wang,Xue Li,Cheng-Wei Wang
Configuring new nanostructured photocatalyst with high efficient photocatalystic capabilities is meaningfully for environmental pollution control. Herein, a p-n heterojunction nanostructured photocatalyst of Ni(OH) 2 /BiVO 4 was well designed and successfully fabricated via a facile solvothermal method, in which Ni(OH) 2 is a wide band-gap semiconductor. Being applied for photo-degradation of anion organic dye, it is found such Ni(OH) 2 /BiVO 4 heterostructures can not only increase the specific surface area and enhance the light response, but also effectively facilitate the photo-generated charge separation and transfer. As a result, 0.5-Ni(OH) 2 /BiVO 4 can possess a photocatalytic capability of 96% and a reaction rate constant 1.9572 h −1 within 90 min irradiation, being 6 and 18 times higher than that of pure BiVO 4 (16%, 0.1098 h −1 ). This study presents a new means to design a kind of high efficient wide band-gap semiconductor constructed BiVO 4 -based photocatalysts.
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INTERNATIONAL JOURNAL OF ENERGY RESEARCH
·
2020
·Vol. 44
·期 6
·4827-4836
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IF 3.741
Mojie Sun,Zhao Wang,Bixue Gao,Shijie Wang,Chi Wang,Xiaochen Song,Dongyao Lin
Summary To circumvent the expensive cost of precious metal electrocatalysts, a hydrothermal method and a plasma-enhanced chemical vapor deposition (PECVD) method have been used to prepareNiS 2 -Ni(OH) 2 /NF-PECVD (N-PECVD) with excellent properties. After XRD, SEM, XPS, and other characterization methods, it can be seen that after the hydrothermal reaction of Ni foam (NF), 50-60 nm Ni(OH) 2 nanosheets have grown on the NF frame. The subsequent PECVD reaction produces 90 nm NiS 2 -Ni(OH) 2 nanosheets on the NF frame. The hydrogen release overpotentials in the acidic solution and alkaline solution are 90 and 95 mV ( j = 10 mA/cm 2 ), respectively. And the Tafel slopes reach 80 and 83.6 mV/dec, respectively. The chronopotential (CP) test shows that the material has good HER stability over 12 h. The results from the subsequent electric double layer capacitance and alternating current impedance (EIS) tests show that N-PECVD synthesized by PECVD has a relatively large active electrochemical surface area (ECSA) and a low electrochemical impedance. This study not only finds good inspiration for the synthesis of cheap HER catalysts but also provides a valuable reference for the synthesis of materials in other fields.
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PHYSICA STATUS SOLIDI A-APPLICATIONS AND MATERIALS SCIENCE
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2020
·Vol. 217
·期 15
·2000135
·
IF 1.759
Jingxue Zhang,Hongtao Cui
The pore-structural ordering in nanosheets-interlinked clusters is a significant issue for the electrochemical performance of Ni(OH) 2 as an electrode material for application in Faraday supercapacitors. Herein, the W/O emulsion stabilized by high shear mixer (HSM) is used as a medium to organize the pore structure in Ni(OH) 2 nanosheets-interlinked spheres. It is found that the water content in emulsion strongly affects the pore structure and surface area of Ni(OH) 2 nanosheets-interlinked spheres formed through the granulation effect of HSM. It is considered that the oil phase as continuous phase in emulsion can reduce the aggregation/agglomeration of Ni(OH) 2 nanosheets, resulting from the strong intermolecular force between nanosheets. As a result, the oil phase in emulsion is beneficial to the formation of ordered pore structure and the increase of surface area in the produced spheres. The characterization results indicate that the sample prepared at a water content of 20 vol% has the largest specific surface area and the well-defined pore structure enclosed with interlinked nanosheets. As a result, this sample presents excellent electrochemical performance and promoted cycling stability.
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JOURNAL OF HAZARDOUS MATERIALS
·
2020
·
IF 9.038
Fanyu Meng,Lina Guo,Haocheng Zou,Boming Zhu,Fayang Zhou,Yiqing Zeng,Jiayou Han,Jun Yang,Shule Zhang,Qin Zhong
To achieve high NO oxidation efficiency, excessive O 3 must be used, which would lead to the high cost and escape of ozone. Herein, we adopted low cost and environmental-friendly TiO 2 as the catalyst of low concentration O 3 and H 2 O 2 system for high-efficiency NO x oxidation. The Ti sites on TiO 2 were the deprotonation sites of H 2 O 2 and H 2 O into Ti-OOH and Ti-OH species, respectively. We found that the surface of rutile phase TiO 2 had a low concentration Ti-OOH component but a large amount of Ti-OH after contacting with H 2 O 2 solution, thus lots of ·OH and a few O 2 − radicals formed with introducing O 3 molecules. H 2 O 2 solution induced the formation of a large amount of Ti-OOH and Ti-OH species on the anatase phase TiO 2 surface, thus lots of O 2 − generated in the O 3 /H 2 O 2 system. O 2 − and O H radicals could efficiently oxidize NO, in which O 2 − radicals could oxidize NO to NO 3 − in one step with high selectively. Therefore, anatase TiO 2 had better performance in NO x oxidation than rutile phase TiO 2 . The effect of temperature and SO 2 concentration on NO oxidation was also investigated, the results showed that TiO 2 -A/O 3 /H 2 O 2 system promoted NO oxidation at a low temperature and a low concentration of SO 2 .
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JOURNAL OF MATERIALS SCIENCE
·
2020
·Vol. 55
·期 26
·12091-12102
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IF 3.553
Sheng Peng,Tao Shi,Gao Xiaorui,Tan Yongjian,Wu Dajun,Qian Bin,Chu Paul K.
Cobalt carbonate hydroxide possesses interesting capacitive properties due to the unique crystal structure. Herein, the hierarchical Co 3 O 4 @Co 2 (CO 3 )(OH) 2 dendritic structure was fabricated on carbon cloth with Co 3 O 4 nanoneedles as the inner core to enhance the conductivity. The loading efficiency of Co 2 (CO 3 )(OH) 2 nanowhiskers had improved obviously, and the nanowires provided more electrochemical sites to facilitate the superior electrochemical energy storage capacity of supercapacitor. The dendritic electrode with the core–shell structure had a high area-specific capacitance (1541 mF cm −2 at 1 mA cm −2 ), good rate capacitance (only 18.1% specific capacitance lost when the current density increased to 5 mA cm −2 ), as well as better electrochemical cycle stability (a capacitance retention of 72.1% after 5000 cycles at a high current density of 5 mA cm −2 ). The dendritic Co 3 O 4 @Co 2 (CO 3 )(OH) 2 and activated carbon as cathode and anode, respectively, were used to assemble an asymmetric supercapacitor, possessing the better area-specific capacitance of 87 mF cm −2 as well as well-deserved longevity retaining approximately 97.3% of initial capacitance even after 10,000 cycles at 1 mA cm −2 . The excellent properties stemmed from electro-active sites galore, strong adhesion between the core and shell, superior conductivity, as well as excellent ion transfer. The novel materials and feasible strategy are promising for next-generation hybrid supercapacitor with high performance.
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CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Sheying Dong,Jie Zhang,Guiqi Huang,Wenbo Wei,Tinglin Huang
The potential application of microporous organic polymers (MOPs) in various fields have been demonstrated. However, further study of MOPs based on novel idea and delicate design remain a challenge. Herein, a unique phloroglucinol-based MOP with large numbers of –OH functional groups (OH-POF) was synthesized via simple and cost-effective microwave synthesis. Interestingly, the π-π interaction and hydrogen bonding among OH-POF, acetylcholinesterase (AChE), and Nafion (NF) are beneficial to the combination of modification materials and immobilized enzymes into a whole on the surface of electrode. Furthermore, special structure and multi-functional integrated OH-POF material with a hierarchical pore system and large specific surface area as well as excellent electrical conductivity was applied as the immobilizations of AChE on carbon paste electrode (CPE) for improving its catalysis ability to construct organophosphate pesticides (OPs) biosensor. The electrochemical analysis of paraoxon and methyl parathion was achieved with wide linear range (5.0 × 10 −13 –1.0 × 10 −8 g∙mL −1 for methyl parathion, 1.0 × 10 −13 –1.0 × 10 −9 g∙mL −1 for paraoxon) and low limit of detection (LOD) (1.5 × 10 −13 g∙mL −1 for methyl parathion, 3.4 × 10 −14 g∙mL −1 for paraoxon). This work demonstrates the potential value of OH-POF material for electrochemical biosensor. Most importantly, it provides a fresh research idea and reference of further exploring the application of other MOPs in the field of environmental analysis.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Shu Wu,Jingjing Guo,Yan Wang
Constructing heterojunction to achieve efficient charge separation and transfer is a significant way to enhance photocatalytic activity. Herein, a novel ternary Bi 2 O 2 CO 3 –Bi 2 O 2 (OH)NO 3 /g-C 3 N 4 (labeled as BOC-BON/CN) heterojunction photocatalyst was successfully synthesized by ion exchange reaction under hydrothermal conditions. The products were characterized by various analytical methods, including X-ray diffraction (XRD), Fourier transform-infrared spectrometer (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray spectrometer (SEM), UV–vis reflectance spectra (UV–vis DRS), photoluminescence (PL), photocurrent response and electrochemical impedance spectroscopy (EIS). Heterojunction formation mechanism and photocatalytic degradation mechanism were discussed in detail. The prepared BOC-BON/CN heterojunction exhibited excellent Rhodamine B (RhB) photodegradation rate of 0.0476 min −1 under visible light, which was 3.55 times of the pristine g-C 3 N 4 (0.0134 min −1 ). The significant increase in photodegradation rate was attributable to the heterojunction structure, which promotes the separation of photogenerated charges. Bi 2 O 2 (OH)NO 3 played an essential role as electron accelerator in the charge transfer process. The internal electric field of Bi 2 O 2 (OH)NO 3 accelerates the directed transfer of electron from g-C 3 N 4 to Bi 2 O 2 CO 3 . This work extends the study of g–C 3 N 4 –based photocatalytic systems and demonstrates Bi 2 O 2 (OH)NO 3 as a promising cocatalyst.
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