Developing an efficient approach of transforming biomass waste to functional carbon-based electrode materials applied in supercapacitor offers an important and high value-added practical application due to the abundan...Developing an efficient approach of transforming biomass waste to functional carbon-based electrode materials applied in supercapacitor offers an important and high value-added practical application due to the abundance and considerable low price of biomass wastes.Herein,a hierarchical carbon functionalized with electrochemical-active oxygen-containing groups was fabricated by microwave treatment from the biomass waste of camellia oleifera.The obtained mesoporous carbon(MAC)owns nanosheet morphology,rich mesoporosity,large surface area(1726 m2/g)and very high oxygenic functionalities(16.2 wt%)with pseudocapacitive activity.Prepared electrode of supercapacitor and tested in 2.0 M H2 SO4,the MAC exhibits an obvious pseudocapacitive activity and achieved a superior supercapacitive performance to that of directly activated carbon(DAC-800)including high specific capacitance(367 F/g vs.298 F/g)and better rate performance(66%vs.44%).The symmetrical supercapacitor based on MAC shows a high capacity of275 F/g,large energy density of 9.55 Wh/kg(at power density of 478 W/kg)and excellent cycling stability with 99%capacitance retention after 10000 continuous charge-discharge,endowing the obtained MAC a promising functional material for electrochemical energy storage.展开更多
The inefficiency of water splitting is mainly due to the sluggish anodic water oxidation reaction. Replacing water oxidation with thermodynamically more favorable selective methanol oxidation reaction and developing r...The inefficiency of water splitting is mainly due to the sluggish anodic water oxidation reaction. Replacing water oxidation with thermodynamically more favorable selective methanol oxidation reaction and developing robust bifunctional electrocatalysts are of great significance. Herein, a hierarchical heteronanostructure with Ni–Co layered double hydroxide(LDH) ultrathin nanosheets coated on cobalt phosphide nanosheets arrays(CoxP@NiCo-LDH) are fabricated and used for co-electrolysis of methanol/water to co-produce value-added formate and hydrogen with saving energy. Benefiting from the fast charge transfer introduced by phosphide nanoarrays, the synergy in nanosheets catalysts with hetero-interface,CoxP@NiCo-LDH/Ni foam(NF) exhibits superior electrocatalytic performance(10 mA cm-2@ 1.24 V and-0.10 V for methanol selective oxidation and hydrogen evolution reaction, respectively). Furthermore,CoxP@NiCo-LDH/NF-based symmetric two-electrode electrolyzer drives a current density of 10 m A cm-2 with a low cell voltage of only 1.43 V and the Faradaic efficiency towards the generation of formate and H2 are close to 100% in the tested range of current density(from 40 to 200 m A cm-2). This work highlights the positive effect of hetero-interaction in the design of more efficient eletrocatalysts and might guide the way towards facile upgrading of alcohols and energy-saving electrolytic H2 co-generation.展开更多
Cor triatriatum dextrum is an extremely rare congenital heart abnormality in which the right atrium is separatedinto two chambers by a persistent fibrous membrane. A transvenous approach to place a dual-chamber pacema...Cor triatriatum dextrum is an extremely rare congenital heart abnormality in which the right atrium is separatedinto two chambers by a persistent fibrous membrane. A transvenous approach to place a dual-chamber pacemaker in such patients is technically challenging. We report the first case of a transvenous permanent pacemaker placement in a patient with cor triatriatum dextrum. An 87-year-old woman was diagnosed with paroxysmal atrial fibrillation. She was accidentally found to have cor triatriatum dextrum during the transesophageal echocardiography(TEE) prior to cardioversion. Later during her hospital stay, it was indicated to place a permanant pacemaker due to high grade atrioventricular block. After thorough reviewing TEE imagings, a transvenous catheter-based approach was decided feasible. Patient successfully received a dual chamber pacemaker through left subclavian venous approach. Furthermore in our case, using specially designed pacemaker leads and cautious intra-procedural maneuvering under fluoroscopic guidance ensured procedural success. In summary, a thorough pre-operative evaluation with transesophageal echocardiography is critical for the planning and eventual success of the transvenous placement of rightsided leads.展开更多
Cardiovascular diseases are a major cause of morbidity and mortality worldwide and there is an urgent need to develop new pharmacotherapies for managing cardiovascular diseases.In China,traditional Chinese medicine ha...Cardiovascular diseases are a major cause of morbidity and mortality worldwide and there is an urgent need to develop new pharmacotherapies for managing cardiovascular diseases.In China,traditional Chinese medicine has been used in clinical settings for thousands of years.Although traditional Chinese medicine is very popular,Western medicine experts have not yet accepted it because some ingredients and mechanisms of action for its therapeutic effect are not fully clear.Emerging evidence has established that traditional Chinese medicine inhibits oxidative stress and inflammatory response,suppresses apoptosis,promotes angiogenesis,regulates autophagy and gut microbiota,and modulates metabolomics,among others.Therefore,it has a beneficial role against cardiovascular disease occurrence and progression,such as atherosclerosis,hypertension,myocardial ischemia/reperfusion injury,myocardial infarction,cardiomyopathy,arrhythmia,cardiac remodeling,pulmonary arterial hypertension,and heart failure.In this review,we have summarized the research progress on the relevant mechanisms by which traditional Chinese medicine regulates cardiovascular diseases in 2020 to reveal its application to cardiovascular disease prevention and/or therapy.展开更多
Recently, a number of large molybdenum (-copper) deposits have been discovered successively in the Laba area, Shangri-La county, northwestern Yunnan province. The investigation confirmed that there is a superlarge por...Recently, a number of large molybdenum (-copper) deposits have been discovered successively in the Laba area, Shangri-La county, northwestern Yunnan province. The investigation confirmed that there is a superlarge porphyry-skarn hydrothermal vein type molybdenum-polymetallic- metallogenic system with the total prediction reservoir of more than 150 mt molybdenum. The porphyry intrusions contributed to the mineralization closely, the superficial little vein molybdenum (-copper, lead, silver) ore-bodies are usually located in faults and fractures, and the deep porphyry type ore-bodies occurred in the granodiorite porphyries, the skarn type ore-bodies occurred in the contact zone intrused into Triassic limestone or Permian basalts. Laba ore block is a new exploration area with great prospecting potential. In order to reduce the target area and guide the further exploration work, the magnetic method measurement about 3.3 square kilometres was carried out in the ore field. This paper presents an application of analyzing the horizontal and vertical derivative, using Fast Fourier Transform (FFT) filter (FFT high-pass, low-pass, cosine roll-off, suscepbility), calculated spectra frequency energy to predict the depth and intensity of the apparent remanence magnetization of source (Hilbert). The calculated results and magnetic anomalous show that the remanence anomaly is caused by the intrusions into the Triassic limestone and Permian basalts with small anomalies, and the depth of located source is not great. We have identified a number of positions to the three drilled well, the drilled result specify interpretation with very high accuracy. The magnetic method is helpful to identify porphyry mineralization, and judge the shape and depth of the concealed ore-bearing intrusive bodies under the similar geological condition.展开更多
Due to their unique properties and uninterrupted breakthrough in a myriad of clean energy-related applications,carbon-based materials have received great interest.However,the low selectivity and poor conductivity are ...Due to their unique properties and uninterrupted breakthrough in a myriad of clean energy-related applications,carbon-based materials have received great interest.However,the low selectivity and poor conductivity are two primary difficulties of traditional carbon-based materials(zero-dimensional(0D)/one-dimensional(1D)/two-dimensional(2D)),enerating inefficient hydrogen production and impeding the future commercialization of carbon-based materials.To improve hydrogen production,attempts are made to enlarge the surface area of porous three-dimensional(3D)carbon-based materials,achieve uniform interconnected porous channels,and enhance their stability,especially under extreme conditions.In this review,the structural advantages and performance improvements of porous carbon nanotubes(CNTs),g-C_(3)N_(4),covalent organic frameworks(COFs),metal-organic frameworks(MOFs),MXenes,and biomass-derived carbon-based materials are firstly summarized,followed by discussing the mechanisms involved and assessing the performance of the main hydrogen production methods.These include,for example,photo/electrocatalytic hydrogen production,release from methanolysis of sodium borohydride,methane decomposition,and pyrolysis-gasification.The role that the active sites of porous carbon-based materials play in promoting charge transport,and enhancing electrical conductivity and stability,in a hydrogen production process is discussed.The current challenges and future directions are also discussed to provide guidelines for the development of next-generation high-efficiency hydrogen 3D porous carbon-based materials prospected.展开更多
Renewable energy powered electrocatalytic water splitting is a promising strategy for hydrogen generation,and the design and development of high-efficiency and earth-abundant electrocatalysts for hydrogen evolution re...Renewable energy powered electrocatalytic water splitting is a promising strategy for hydrogen generation,and the design and development of high-efficiency and earth-abundant electrocatalysts for hydrogen evolution reaction(HER)are highly desirable.Herein,MoS2 nanoflowers decorated two-dimensional carbonitride-based MXene Ti3CN(OH)x hybrids have been constructed by etching and post-hydrothermal methods.The electrochemical performance of the as-obtained Ti_(3)CN(OH)_(x)@MoS_(2)hybrids having a quasi core-shell structure is fascinating:An overpotential of 120 mV and a Tafel slope of 64 mV∙dec^(−1)can be delivered at a current density of 10 mA∙cm^(−2).And after 3,000 cyclic voltammetry cycles,it can be seen that there is no apparent attenuation.Both the experimental results and density functional theory(DFT)calculations indicate that the synergetic effects between Ti_(3)CN(OH)x and MoS_(2)are responsible for the robust electrochemical HER performance.The electrons of-OH group in Ti_(3)CN(OH)x are transferred to MoS_(2),making the adsorption energy of the composite for H almost vanish.The metallic Ti_(3)CN(OH)x is also beneficial to the fast charge transfer kinetics.The construction of MXene-based hybrids with optimal electronic structure and unique morphology tailored to the applications can be further used in other promising energy storage and conversion devices.展开更多
CoS_(2) is considered to be a promising electrocatalyst for hydrogen evolution reaction(HER).However,its further widespread applications are hampered by the unsatisfactory activity due to relatively high chemisorption...CoS_(2) is considered to be a promising electrocatalyst for hydrogen evolution reaction(HER).However,its further widespread applications are hampered by the unsatisfactory activity due to relatively high chemisorption energy for hydrogen atom.Herein,theoretical predictions of first-principles calculations reveal that the introduction of a Cl-terminated MXenes-Ti_(3)CNCl_(2) can significantly reduce the HER potential of CoS_(2)-based materials and the Ti_(3)CNCl_(2)@CoS_(2) core–shell nanostructure has Gibbs free energy of hydrogen adsorption(|ΔGH|)close to zero,much lower than that of the pristine CoS_(2) and Ti_(3)CNCl_(2).Inspired by the theoretical predictions,we have successfully fabricated a unique Ti_(3)CNCl_(2)@CoS_(2) core–shell nanostructure by ingeniously coupling CoS_(2) with a Cl-terminated MXenes-Ti_(3)CNCl_(2).Interface-charge transfer between CoS_(2) and Ti_(3)CNCl_(2) results in a higher degree of electronic localization and a formation of chemical bonding.Thus,the Ti_(3)CNCl_(2)@CoS_(2) core–shell nanostructure achieves a significant enhancement in HER activity compared to pristine CoS_(2) and Ti_(3)CNCl_(2).Theoretical calculations further confirm that the partial density of states of CoS_(2) after hybridization becomes more non-localized,and easier to interact with hydrogen ions,thus boosting HER performance.In this work,the success of oriented experimental fabrication of high-efficiency Ti_(3)CNCl_(2)@CoS_(2) electrocatalysts guided by theoretical predictions provides a powerful lead for the further strategic design and fabrication of efficient HER electrocatalysts.展开更多
In this work, a series of Pt nanocrystallines(Pt NCs) supported on TiO2 substrate with controlled thickness of carbon layers(C-Pt/TiO2) were synthesized. Well-dispersed Pt NCs were facilely synthesized at room tem...In this work, a series of Pt nanocrystallines(Pt NCs) supported on TiO2 substrate with controlled thickness of carbon layers(C-Pt/TiO2) were synthesized. Well-dispersed Pt NCs were facilely synthesized at room temperature by a photo-reduction process in lytropic liquid crystal(LCs). Surface tuning of the carbon layers on Pt/TiO2 catalysts was achieved by varying the calcination atmospheres(in argon, air, and oxygen) and characterized by XPS and HRTEM. The influence of the coated carbon layers on the catalytic activity of catalysts is investigated by CO oxidation reaction which presented the following ranks: C-Pt/TiO2-O2〉 C-Pt/TiO2-Air 〉 C-Pt/TiO2-Ar. It is found that the carbon layer coating can stabilize the Pt NCs and enable them anti-sintering at high temperature. This finding provides new insight into understanding the C-Pt/TiO2 ternary system for tuning their catalytic performance.展开更多
In this paper, highly dispersive nanosized copper particles with a mean particle size of less than 6 nm are prepared by an environmentally friendly chemical reduction method. Non-toxic L-ascorbic acid acts as both red...In this paper, highly dispersive nanosized copper particles with a mean particle size of less than 6 nm are prepared by an environmentally friendly chemical reduction method. Non-toxic L-ascorbic acid acts as both reducing agent and antioxidant in ethylene glycol in the absence of any other capping agent. Transmission electron microscopy (TEM) is used to characterize the size and morphology of Cu nanoparticles. The results of UV-Vis spectroscopy (UV-Vis), energy dispersive spectroscopy (EDS) and high resolution TEM (HRTEM) illustrate that the resultant product is pure Cu nanocrystals. The size of Cu nanoparticles is remarkably impacted by the order of reagent addition, and the investigation reveals the reaction procedure of Cu^2+ ions and L-ascorbic acid.展开更多
The growth of a Ni(OH)2 coating on conductive carbon substrates is an efficient way to address issues related to their poor conductivity in electrochemical capacitor applications. However, the direct growth of nicke...The growth of a Ni(OH)2 coating on conductive carbon substrates is an efficient way to address issues related to their poor conductivity in electrochemical capacitor applications. However, the direct growth of nickel hydroxide coatings on a carbon substrate is challenging, because the surfaces of these systems are not compatible and a preoxidation treatment of the conductive carbon substrate is usually required. Herein, we present a facile preoxidation-free approach to fabricate a uniform Ni(OH)2 coating on carbon nanosheets (CNs) by an ion-exchange reaction to achieve the in situ transformation of a MgO/C composite to a Ni(OH)2/C one. The obtained Ni(OH)2/CNs hybrids possess nanosheet morphology, a large surface area (278 m2/g), and homogeneous elemental distributions. When employed as supercapacitors in a three-electrode configuration, the Ni(OH)JCNs hybrid achieves a large capacitance of 2,218 F/g at a current density of 1.0 A/g. Moreover, asymmetric supercapacitors fabricated with the Ni(OH)2/CNs hybrid exhibit superior supercapacitive performances, with a large capacity of 198 F/g, and high energy density of 56.7 Wh/kg at a power density of 4.0 kW/kg. They show excellent cycling stability with 93% capacity retention after 10,000 cycles, making the Ni(OH)2/CNs hybrid a promising candidate for practical applications in supercapacitor devices.展开更多
赝电容超级电容器具有高功率密度、超长寿命以及可靠的安全性,使其在能源转化和存储中扮演着重要角色.但是,设计具有高容量、优异倍率性能以及出色的机械稳定性的电极材料依旧是一个挑战.本工作中,我们采用室温部分硫化策略来调节氢氧...赝电容超级电容器具有高功率密度、超长寿命以及可靠的安全性,使其在能源转化和存储中扮演着重要角色.但是,设计具有高容量、优异倍率性能以及出色的机械稳定性的电极材料依旧是一个挑战.本工作中,我们采用室温部分硫化策略来调节氢氧化钴纳米片的电子结构和晶态.得到的羟基硫化钴具有无定形结构,同时还有丰富的低价钴离子.三电极体系下,该电极在电流密度为1 A g^-1时的比电容达2110 F g^-1,当电流密度增大至10 A g^-1时容量仍有92.1%的保留,容量和倍率性能都远高于氢氧化钴前驱体(916 F g^-1@1 A g^-1,10 A g^-1的比电容保留率为80%).此外,利用该电极与商业活性炭组成的不对称电容器具有44.9 W h kg^-1的高能量密度以及优异的稳定性(8000次循环后仅衰减4%).展开更多
基金financially supported by the National Key Technology R&D Program of China(2017YFB0310704)the National Natural Science Foundation of China(21773112 and 21173119)the Fundamental Research Funds for the Central Universities
文摘Developing an efficient approach of transforming biomass waste to functional carbon-based electrode materials applied in supercapacitor offers an important and high value-added practical application due to the abundance and considerable low price of biomass wastes.Herein,a hierarchical carbon functionalized with electrochemical-active oxygen-containing groups was fabricated by microwave treatment from the biomass waste of camellia oleifera.The obtained mesoporous carbon(MAC)owns nanosheet morphology,rich mesoporosity,large surface area(1726 m2/g)and very high oxygenic functionalities(16.2 wt%)with pseudocapacitive activity.Prepared electrode of supercapacitor and tested in 2.0 M H2 SO4,the MAC exhibits an obvious pseudocapacitive activity and achieved a superior supercapacitive performance to that of directly activated carbon(DAC-800)including high specific capacitance(367 F/g vs.298 F/g)and better rate performance(66%vs.44%).The symmetrical supercapacitor based on MAC shows a high capacity of275 F/g,large energy density of 9.55 Wh/kg(at power density of 478 W/kg)and excellent cycling stability with 99%capacitance retention after 10000 continuous charge-discharge,endowing the obtained MAC a promising functional material for electrochemical energy storage.
基金financially supported by the National Natural Science Foundation of China(Nos.21975163 and 21905181)。
文摘The inefficiency of water splitting is mainly due to the sluggish anodic water oxidation reaction. Replacing water oxidation with thermodynamically more favorable selective methanol oxidation reaction and developing robust bifunctional electrocatalysts are of great significance. Herein, a hierarchical heteronanostructure with Ni–Co layered double hydroxide(LDH) ultrathin nanosheets coated on cobalt phosphide nanosheets arrays(CoxP@NiCo-LDH) are fabricated and used for co-electrolysis of methanol/water to co-produce value-added formate and hydrogen with saving energy. Benefiting from the fast charge transfer introduced by phosphide nanoarrays, the synergy in nanosheets catalysts with hetero-interface,CoxP@NiCo-LDH/Ni foam(NF) exhibits superior electrocatalytic performance(10 mA cm-2@ 1.24 V and-0.10 V for methanol selective oxidation and hydrogen evolution reaction, respectively). Furthermore,CoxP@NiCo-LDH/NF-based symmetric two-electrode electrolyzer drives a current density of 10 m A cm-2 with a low cell voltage of only 1.43 V and the Faradaic efficiency towards the generation of formate and H2 are close to 100% in the tested range of current density(from 40 to 200 m A cm-2). This work highlights the positive effect of hetero-interaction in the design of more efficient eletrocatalysts and might guide the way towards facile upgrading of alcohols and energy-saving electrolytic H2 co-generation.
文摘Cor triatriatum dextrum is an extremely rare congenital heart abnormality in which the right atrium is separatedinto two chambers by a persistent fibrous membrane. A transvenous approach to place a dual-chamber pacemaker in such patients is technically challenging. We report the first case of a transvenous permanent pacemaker placement in a patient with cor triatriatum dextrum. An 87-year-old woman was diagnosed with paroxysmal atrial fibrillation. She was accidentally found to have cor triatriatum dextrum during the transesophageal echocardiography(TEE) prior to cardioversion. Later during her hospital stay, it was indicated to place a permanant pacemaker due to high grade atrioventricular block. After thorough reviewing TEE imagings, a transvenous catheter-based approach was decided feasible. Patient successfully received a dual chamber pacemaker through left subclavian venous approach. Furthermore in our case, using specially designed pacemaker leads and cautious intra-procedural maneuvering under fluoroscopic guidance ensured procedural success. In summary, a thorough pre-operative evaluation with transesophageal echocardiography is critical for the planning and eventual success of the transvenous placement of rightsided leads.
文摘Cardiovascular diseases are a major cause of morbidity and mortality worldwide and there is an urgent need to develop new pharmacotherapies for managing cardiovascular diseases.In China,traditional Chinese medicine has been used in clinical settings for thousands of years.Although traditional Chinese medicine is very popular,Western medicine experts have not yet accepted it because some ingredients and mechanisms of action for its therapeutic effect are not fully clear.Emerging evidence has established that traditional Chinese medicine inhibits oxidative stress and inflammatory response,suppresses apoptosis,promotes angiogenesis,regulates autophagy and gut microbiota,and modulates metabolomics,among others.Therefore,it has a beneficial role against cardiovascular disease occurrence and progression,such as atherosclerosis,hypertension,myocardial ischemia/reperfusion injury,myocardial infarction,cardiomyopathy,arrhythmia,cardiac remodeling,pulmonary arterial hypertension,and heart failure.In this review,we have summarized the research progress on the relevant mechanisms by which traditional Chinese medicine regulates cardiovascular diseases in 2020 to reveal its application to cardiovascular disease prevention and/or therapy.
文摘Recently, a number of large molybdenum (-copper) deposits have been discovered successively in the Laba area, Shangri-La county, northwestern Yunnan province. The investigation confirmed that there is a superlarge porphyry-skarn hydrothermal vein type molybdenum-polymetallic- metallogenic system with the total prediction reservoir of more than 150 mt molybdenum. The porphyry intrusions contributed to the mineralization closely, the superficial little vein molybdenum (-copper, lead, silver) ore-bodies are usually located in faults and fractures, and the deep porphyry type ore-bodies occurred in the granodiorite porphyries, the skarn type ore-bodies occurred in the contact zone intrused into Triassic limestone or Permian basalts. Laba ore block is a new exploration area with great prospecting potential. In order to reduce the target area and guide the further exploration work, the magnetic method measurement about 3.3 square kilometres was carried out in the ore field. This paper presents an application of analyzing the horizontal and vertical derivative, using Fast Fourier Transform (FFT) filter (FFT high-pass, low-pass, cosine roll-off, suscepbility), calculated spectra frequency energy to predict the depth and intensity of the apparent remanence magnetization of source (Hilbert). The calculated results and magnetic anomalous show that the remanence anomaly is caused by the intrusions into the Triassic limestone and Permian basalts with small anomalies, and the depth of located source is not great. We have identified a number of positions to the three drilled well, the drilled result specify interpretation with very high accuracy. The magnetic method is helpful to identify porphyry mineralization, and judge the shape and depth of the concealed ore-bearing intrusive bodies under the similar geological condition.
基金supported by the National Natural Science Foundation of China(No.62004143)the Central Government Guided Local Science and Technology Development Special Fund Project(No.2020ZYYD033)+1 种基金the Opening Fund of Key Laboratory for Green Chemical Process of Ministry of Education of Wuhan Institute of Technology(No.GCP202101)the Natural Science Fund of Hubei Province(No.2021CFB133).
文摘Due to their unique properties and uninterrupted breakthrough in a myriad of clean energy-related applications,carbon-based materials have received great interest.However,the low selectivity and poor conductivity are two primary difficulties of traditional carbon-based materials(zero-dimensional(0D)/one-dimensional(1D)/two-dimensional(2D)),enerating inefficient hydrogen production and impeding the future commercialization of carbon-based materials.To improve hydrogen production,attempts are made to enlarge the surface area of porous three-dimensional(3D)carbon-based materials,achieve uniform interconnected porous channels,and enhance their stability,especially under extreme conditions.In this review,the structural advantages and performance improvements of porous carbon nanotubes(CNTs),g-C_(3)N_(4),covalent organic frameworks(COFs),metal-organic frameworks(MOFs),MXenes,and biomass-derived carbon-based materials are firstly summarized,followed by discussing the mechanisms involved and assessing the performance of the main hydrogen production methods.These include,for example,photo/electrocatalytic hydrogen production,release from methanolysis of sodium borohydride,methane decomposition,and pyrolysis-gasification.The role that the active sites of porous carbon-based materials play in promoting charge transport,and enhancing electrical conductivity and stability,in a hydrogen production process is discussed.The current challenges and future directions are also discussed to provide guidelines for the development of next-generation high-efficiency hydrogen 3D porous carbon-based materials prospected.
基金supported by the National Natural Science Foundation of China(Nos.62004143 and 21902108)the Key Research and Development(R&D)Program of Hubei Province(No.2022BAA084)+1 种基金the Central Government Guided Local Science and Technology Development Special Fund Project(No.2020ZYYD033),the Natural Science Foundation of Hubei Province(No.2021CFB133)the Knowledge Innovation Program of Wuhan-Shuguang Project(No.2022010801020355).
文摘Renewable energy powered electrocatalytic water splitting is a promising strategy for hydrogen generation,and the design and development of high-efficiency and earth-abundant electrocatalysts for hydrogen evolution reaction(HER)are highly desirable.Herein,MoS2 nanoflowers decorated two-dimensional carbonitride-based MXene Ti3CN(OH)x hybrids have been constructed by etching and post-hydrothermal methods.The electrochemical performance of the as-obtained Ti_(3)CN(OH)_(x)@MoS_(2)hybrids having a quasi core-shell structure is fascinating:An overpotential of 120 mV and a Tafel slope of 64 mV∙dec^(−1)can be delivered at a current density of 10 mA∙cm^(−2).And after 3,000 cyclic voltammetry cycles,it can be seen that there is no apparent attenuation.Both the experimental results and density functional theory(DFT)calculations indicate that the synergetic effects between Ti_(3)CN(OH)x and MoS_(2)are responsible for the robust electrochemical HER performance.The electrons of-OH group in Ti_(3)CN(OH)x are transferred to MoS_(2),making the adsorption energy of the composite for H almost vanish.The metallic Ti_(3)CN(OH)x is also beneficial to the fast charge transfer kinetics.The construction of MXene-based hybrids with optimal electronic structure and unique morphology tailored to the applications can be further used in other promising energy storage and conversion devices.
基金supported by the National Natural Science Foundation of China(No.62004143)the Central Government Guided Local Science and Technology Development Special Fund Project(No.2020ZYYD033)+3 种基金the Natural Science Foundation of Hubei Province(No.2021CFB133)the Opening Fund of Key Laboratory of Rare Mineral,Ministry of Natural Resources(No.KLRM-KF 202005)the Opening Fund of Key Laboratory for Green Chemical Process of Ministry of Education of Wuhan Institute of Technology(No.GCP202101)the Innovation Project of Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education(No.LCX2021003).
文摘CoS_(2) is considered to be a promising electrocatalyst for hydrogen evolution reaction(HER).However,its further widespread applications are hampered by the unsatisfactory activity due to relatively high chemisorption energy for hydrogen atom.Herein,theoretical predictions of first-principles calculations reveal that the introduction of a Cl-terminated MXenes-Ti_(3)CNCl_(2) can significantly reduce the HER potential of CoS_(2)-based materials and the Ti_(3)CNCl_(2)@CoS_(2) core–shell nanostructure has Gibbs free energy of hydrogen adsorption(|ΔGH|)close to zero,much lower than that of the pristine CoS_(2) and Ti_(3)CNCl_(2).Inspired by the theoretical predictions,we have successfully fabricated a unique Ti_(3)CNCl_(2)@CoS_(2) core–shell nanostructure by ingeniously coupling CoS_(2) with a Cl-terminated MXenes-Ti_(3)CNCl_(2).Interface-charge transfer between CoS_(2) and Ti_(3)CNCl_(2) results in a higher degree of electronic localization and a formation of chemical bonding.Thus,the Ti_(3)CNCl_(2)@CoS_(2) core–shell nanostructure achieves a significant enhancement in HER activity compared to pristine CoS_(2) and Ti_(3)CNCl_(2).Theoretical calculations further confirm that the partial density of states of CoS_(2) after hybridization becomes more non-localized,and easier to interact with hydrogen ions,thus boosting HER performance.In this work,the success of oriented experimental fabrication of high-efficiency Ti_(3)CNCl_(2)@CoS_(2) electrocatalysts guided by theoretical predictions provides a powerful lead for the further strategic design and fabrication of efficient HER electrocatalysts.
基金supported by the National Natural Science Foundation of China(62004143)the Key R&D Program of Hubei Province(2022BAA084)+2 种基金the Central Government Guided Local Science and Technology Development Special Fund Project(2020ZYYD033)the Opening Fund of the Key Laboratory of Rare Mineral,Ministry of Natural Resources(KLRM-KF 202005)the Opening Fund of the Key Laboratory for Green Chemical Process of Ministry of Education of Wuhan Institute of Technology(GCP202101)。
基金financially supported by the National Key Technology R&D Program of China (No. 2017YFB0310704)the National Natural Science Foundation of China (Nos. 21773112, 21173119 and 21303083)+2 种基金Natural Science Foundation of the Higher Education Institutions of Jiangsu Province (No. 17KJB150001)the Natural Science Foundation of Jiangsu Province (No. BK20130563)the Fundamental Research Funds for the Central Universities
文摘In this work, a series of Pt nanocrystallines(Pt NCs) supported on TiO2 substrate with controlled thickness of carbon layers(C-Pt/TiO2) were synthesized. Well-dispersed Pt NCs were facilely synthesized at room temperature by a photo-reduction process in lytropic liquid crystal(LCs). Surface tuning of the carbon layers on Pt/TiO2 catalysts was achieved by varying the calcination atmospheres(in argon, air, and oxygen) and characterized by XPS and HRTEM. The influence of the coated carbon layers on the catalytic activity of catalysts is investigated by CO oxidation reaction which presented the following ranks: C-Pt/TiO2-O2〉 C-Pt/TiO2-Air 〉 C-Pt/TiO2-Ar. It is found that the carbon layer coating can stabilize the Pt NCs and enable them anti-sintering at high temperature. This finding provides new insight into understanding the C-Pt/TiO2 ternary system for tuning their catalytic performance.
基金Acknowledgement This work is sponsored by the National Natural Science Foundation of China (No. 51202175) and the Natural Science Foundation of Hubei Province (No. 2011 CDB245).
文摘In this paper, highly dispersive nanosized copper particles with a mean particle size of less than 6 nm are prepared by an environmentally friendly chemical reduction method. Non-toxic L-ascorbic acid acts as both reducing agent and antioxidant in ethylene glycol in the absence of any other capping agent. Transmission electron microscopy (TEM) is used to characterize the size and morphology of Cu nanoparticles. The results of UV-Vis spectroscopy (UV-Vis), energy dispersive spectroscopy (EDS) and high resolution TEM (HRTEM) illustrate that the resultant product is pure Cu nanocrystals. The size of Cu nanoparticles is remarkably impacted by the order of reagent addition, and the investigation reveals the reaction procedure of Cu^2+ ions and L-ascorbic acid.
文摘The growth of a Ni(OH)2 coating on conductive carbon substrates is an efficient way to address issues related to their poor conductivity in electrochemical capacitor applications. However, the direct growth of nickel hydroxide coatings on a carbon substrate is challenging, because the surfaces of these systems are not compatible and a preoxidation treatment of the conductive carbon substrate is usually required. Herein, we present a facile preoxidation-free approach to fabricate a uniform Ni(OH)2 coating on carbon nanosheets (CNs) by an ion-exchange reaction to achieve the in situ transformation of a MgO/C composite to a Ni(OH)2/C one. The obtained Ni(OH)2/CNs hybrids possess nanosheet morphology, a large surface area (278 m2/g), and homogeneous elemental distributions. When employed as supercapacitors in a three-electrode configuration, the Ni(OH)JCNs hybrid achieves a large capacitance of 2,218 F/g at a current density of 1.0 A/g. Moreover, asymmetric supercapacitors fabricated with the Ni(OH)2/CNs hybrid exhibit superior supercapacitive performances, with a large capacity of 198 F/g, and high energy density of 56.7 Wh/kg at a power density of 4.0 kW/kg. They show excellent cycling stability with 93% capacity retention after 10,000 cycles, making the Ni(OH)2/CNs hybrid a promising candidate for practical applications in supercapacitor devices.
基金surpported by the National Natural Science Foundation of China(21902108,21975163 and 51902204)China Postdoctoral Science Foundation(2019M663035)。
文摘赝电容超级电容器具有高功率密度、超长寿命以及可靠的安全性,使其在能源转化和存储中扮演着重要角色.但是,设计具有高容量、优异倍率性能以及出色的机械稳定性的电极材料依旧是一个挑战.本工作中,我们采用室温部分硫化策略来调节氢氧化钴纳米片的电子结构和晶态.得到的羟基硫化钴具有无定形结构,同时还有丰富的低价钴离子.三电极体系下,该电极在电流密度为1 A g^-1时的比电容达2110 F g^-1,当电流密度增大至10 A g^-1时容量仍有92.1%的保留,容量和倍率性能都远高于氢氧化钴前驱体(916 F g^-1@1 A g^-1,10 A g^-1的比电容保留率为80%).此外,利用该电极与商业活性炭组成的不对称电容器具有44.9 W h kg^-1的高能量密度以及优异的稳定性(8000次循环后仅衰减4%).