Ti3C2Tx,a novel two-dimensional layer material,is widely used as electrode materials of supercapacitor due to its good metal conductivity,redox reaction active surface,and so on.However,there are many challenges to be...Ti3C2Tx,a novel two-dimensional layer material,is widely used as electrode materials of supercapacitor due to its good metal conductivity,redox reaction active surface,and so on.However,there are many challenges to be addressed which impede Ti3C2Tx obtaining the ideal specific capacitance,such as restacking,re-crushing,and oxidation of titanium.Recently,many advances have been proposed to enhance capacitance performance of Ti3C2Tx.In this review,recent strategies for improving specific capacitance are summarized and compared,for example,film formation,surface modification,and composite method.Furthermore,in order to comprehend the mechanism of those efforts,this review analyzes the energy storage performance in different electrolytes and influencing factors.This review is expected to predict redouble research direction of Ti3C2Tx materials in supercapacitors.展开更多
MXene-based materials have gained considerable attention for lithium-sulfur(Li-S)batteries cathode materials due to their superior electric conductivity and high affinitive to polysulfides.However,there are still chal...MXene-based materials have gained considerable attention for lithium-sulfur(Li-S)batteries cathode materials due to their superior electric conductivity and high affinitive to polysulfides.However,there are still challenges in modifying the surface functional groups of MXene to further improve the electrochemical performance and increase the structure variety for MXene-based sulfur host.Herein,we report an efficient and flexible nucleophilic substitution(S_(N))strategy to modify the Ti_(3)C_(2)T_(x) surface terminations and purposefully designed Magnolol-modified Ti_(3)C_(2)T_(x)(M-Ti_(3)C_(2)T_(x))as powerful cathode host materials.Benefiting from more C-Ti-O bonds forming and diallyl groups terminations reducing after the dehalogenation and nucleophilic addition reactions,the given M-Ti_(3)C_(2)T_(x) electrode could effectively suppress the lithium polysulfides shuttling via chemisorption and C—S covalent bond formation.Besides,the Magnolol-modified Ti_(3)C_(2)T_(x) significantly accelerates polysulfide redox reaction and reduces the activation energy of Li_(2) S decomposition.As a result,the as-prepared M-Ti_(3)C_(2)T_(x) electrode displays an excellent rate capability and a high reversible capacity of 7.68 mAh cm^(-2)even under 7.2 mg cm^(-2)S-loaded with a low decay rate of 0.07%(from 2 nd cycle).This flexible surface-modified strategy for MXene terminations is expected to be extended to other diverse MXene applications.展开更多
Few-layer Ti3C2Tx MXene is synthesized from multi-layered Ti3C2Tx via a flash freezing-assisted delamination process.During the flash freezing process,the water molecules in the interlayers of multi-layered MXene are ...Few-layer Ti3C2Tx MXene is synthesized from multi-layered Ti3C2Tx via a flash freezing-assisted delamination process.During the flash freezing process,the water molecules in the interlayers of multi-layered MXene are induced to rearrange and produce volume expansion,thus notably expand the MXenes’interlayer distance to form few-layer MXene.The synthesized few-layer Ti3C2Tx MXene nanosheets display a very small thickness(less than 5 Ti3C2 atom-layers)and expanded interlayer spacing.Consequently,the few-layer Ti3C2Tx exhibits enhanced capacitance(255 F g^-1 vs.177 F g^-1 for the multi-layered Ti3C2Tx)and significantly optimized rate capability(150 F g^-1 at 200 mV s^-1 vs.25 F g^-1 for the multi-layered Ti3C2Tx),because redox-active sites in the few-layer MXene are easily accessible to electrolyte ions.Moreover,an asymmetric supercapacitor is constructed using the few-layer Ti3C2Tx negative electrode and an activated carbon fiber positive electrode.The asymmetric supercapacitor presents a high energy density of 17.9 Wh kg^-1 and a high power density of 14 kW kg^-1,which is inseparable from its wide voltage window of 1.4 V and the good rate performance of the few-layer Ti3C2Tx MXene electrode.Overall,the flash freezing-assist delamination provides an effective and environmental-friendly strategy to synthesize few-layer MXene materials for high-rate electrochemical energy storage.展开更多
Magnesium(Mg)stands out in temporary biomaterial applications due to its biocompatibility,biodegradability,and low Young’s modulus.However,controlling its corrosion through next-generation polymer-based functional co...Magnesium(Mg)stands out in temporary biomaterial applications due to its biocompatibility,biodegradability,and low Young’s modulus.However,controlling its corrosion through next-generation polymer-based functional coatings is crucial due to the rapid degradation behavior of Mg.In this study,the function of 2D lamellar Ti_(3)C_(2)T_(x)(MXene)in Hydroxyapatite(HA)and Halloysite nanotube(HNT)hybrid coatings in biodegradable poly-(lactic acid)(PLA)was investigated.The morphological and structural characterizations of the coatings on Mg were revealed through HRTEM,XPS,SEM-EDX,XRD,FTIR,and contact angle analyses/tests.Electrochemical in vitro corrosion tests(OCP,PDS,and EIS-Nyquist)were conducted for evaluate corrosion resistance under simulated body fluid(SBF)conditions.The bioactivity of the coatings in SBF have been revealed in accordance with the ISO 23,317 standard.Finally,antibacterial disk diffusion tests were conducted to investigate the functional effect of MXene in coatings.It has been determined that the presence of MXene in the coating increased not only surface wettability(131°,85°,77°,and 74°for uncoated,pH,PHH,and PHH/MXene coatings,respectively)but also increased corrosion resistance(1857.850,42.357,1.593,and 0.085×10^(-6),A/cm^(2) for uncoated,pH,PHH,and PHH/MXene coatings,respectively).It has been proven that the in vitro bioactivity of PLA-HA coatings is further enhanced by adding HNT and MXene,along with SEM morphologies after SBF.Finally,2D lamellar MXene-filled coating exhibits antibacterial behavior against both E.coli and S.aureus bacteria.展开更多
Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical co...Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical conductivity,high solar absorptivity,and low infrared emissivity at the same time are rare in na-ture,which are highly anticipated and of great significance for highly efficient electric/solar heating.In this work,we demonstrate that Ti_(3)C_(2)T_(x) MXene with low IR emissivity(14.5%)fills the gap in the absence of the above materials,exhibiting a remarkable electric/solar heating performance.The saturated heating temperature of Ti_(3)C_(2)T_(x) film reaches a record-high value of 201°C at a low driving voltage of 1.5 V,and reaches 84.3°C under practical solar irradiation(750 W/m^(2))with a high solar to the thermal conversion efficiency of 75.3%,which is far superior to other reported materials.Meanwhile,the low IR emissivity endows Ti_(3)C_(2)T_(x) with a remarkable passive radiative heating capability of 7.0°C,ensuring zero-energy heating without electric/solar energy supply.The intrinsic characteristic of high electrical conductivity,high solar absorptivity,and low IR emissivity makes Ti_(3)C_(2)T_(x) unique existence in nature,which is highly promising for all-day and all-weather energy-saving heating.展开更多
基金National Natural Science Foundation of China with Grant No.21905304Natural Science Foundation of Shandong Province(No.ZR2019BEM031)the Fundamental Research Funds for the Central Universities(Nos.18CX02158A and 19CX05001A).
文摘Ti3C2Tx,a novel two-dimensional layer material,is widely used as electrode materials of supercapacitor due to its good metal conductivity,redox reaction active surface,and so on.However,there are many challenges to be addressed which impede Ti3C2Tx obtaining the ideal specific capacitance,such as restacking,re-crushing,and oxidation of titanium.Recently,many advances have been proposed to enhance capacitance performance of Ti3C2Tx.In this review,recent strategies for improving specific capacitance are summarized and compared,for example,film formation,surface modification,and composite method.Furthermore,in order to comprehend the mechanism of those efforts,this review analyzes the energy storage performance in different electrolytes and influencing factors.This review is expected to predict redouble research direction of Ti3C2Tx materials in supercapacitors.
基金the support from CNPC Innovation Found(2021DQ02-1001)Liao Ning Revitalization Talents Program(XLYC1907144)Xinghai Talent Cultivation Plan(X20200303)。
文摘MXene-based materials have gained considerable attention for lithium-sulfur(Li-S)batteries cathode materials due to their superior electric conductivity and high affinitive to polysulfides.However,there are still challenges in modifying the surface functional groups of MXene to further improve the electrochemical performance and increase the structure variety for MXene-based sulfur host.Herein,we report an efficient and flexible nucleophilic substitution(S_(N))strategy to modify the Ti_(3)C_(2)T_(x) surface terminations and purposefully designed Magnolol-modified Ti_(3)C_(2)T_(x)(M-Ti_(3)C_(2)T_(x))as powerful cathode host materials.Benefiting from more C-Ti-O bonds forming and diallyl groups terminations reducing after the dehalogenation and nucleophilic addition reactions,the given M-Ti_(3)C_(2)T_(x) electrode could effectively suppress the lithium polysulfides shuttling via chemisorption and C—S covalent bond formation.Besides,the Magnolol-modified Ti_(3)C_(2)T_(x) significantly accelerates polysulfide redox reaction and reduces the activation energy of Li_(2) S decomposition.As a result,the as-prepared M-Ti_(3)C_(2)T_(x) electrode displays an excellent rate capability and a high reversible capacity of 7.68 mAh cm^(-2)even under 7.2 mg cm^(-2)S-loaded with a low decay rate of 0.07%(from 2 nd cycle).This flexible surface-modified strategy for MXene terminations is expected to be extended to other diverse MXene applications.
基金financial supports from Shenzhen Technical Plan Project(No.JCYJ20160301154114273No.JCYJ20170412171430026)+2 种基金International Science and Technology Cooperation Program of China(No.2016YFE0102200)National Key Basic Research(973)Program of China(No.2014CB932400)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(2017BT01N111)。
文摘Few-layer Ti3C2Tx MXene is synthesized from multi-layered Ti3C2Tx via a flash freezing-assisted delamination process.During the flash freezing process,the water molecules in the interlayers of multi-layered MXene are induced to rearrange and produce volume expansion,thus notably expand the MXenes’interlayer distance to form few-layer MXene.The synthesized few-layer Ti3C2Tx MXene nanosheets display a very small thickness(less than 5 Ti3C2 atom-layers)and expanded interlayer spacing.Consequently,the few-layer Ti3C2Tx exhibits enhanced capacitance(255 F g^-1 vs.177 F g^-1 for the multi-layered Ti3C2Tx)and significantly optimized rate capability(150 F g^-1 at 200 mV s^-1 vs.25 F g^-1 for the multi-layered Ti3C2Tx),because redox-active sites in the few-layer MXene are easily accessible to electrolyte ions.Moreover,an asymmetric supercapacitor is constructed using the few-layer Ti3C2Tx negative electrode and an activated carbon fiber positive electrode.The asymmetric supercapacitor presents a high energy density of 17.9 Wh kg^-1 and a high power density of 14 kW kg^-1,which is inseparable from its wide voltage window of 1.4 V and the good rate performance of the few-layer Ti3C2Tx MXene electrode.Overall,the flash freezing-assist delamination provides an effective and environmental-friendly strategy to synthesize few-layer MXene materials for high-rate electrochemical energy storage.
文摘Magnesium(Mg)stands out in temporary biomaterial applications due to its biocompatibility,biodegradability,and low Young’s modulus.However,controlling its corrosion through next-generation polymer-based functional coatings is crucial due to the rapid degradation behavior of Mg.In this study,the function of 2D lamellar Ti_(3)C_(2)T_(x)(MXene)in Hydroxyapatite(HA)and Halloysite nanotube(HNT)hybrid coatings in biodegradable poly-(lactic acid)(PLA)was investigated.The morphological and structural characterizations of the coatings on Mg were revealed through HRTEM,XPS,SEM-EDX,XRD,FTIR,and contact angle analyses/tests.Electrochemical in vitro corrosion tests(OCP,PDS,and EIS-Nyquist)were conducted for evaluate corrosion resistance under simulated body fluid(SBF)conditions.The bioactivity of the coatings in SBF have been revealed in accordance with the ISO 23,317 standard.Finally,antibacterial disk diffusion tests were conducted to investigate the functional effect of MXene in coatings.It has been determined that the presence of MXene in the coating increased not only surface wettability(131°,85°,77°,and 74°for uncoated,pH,PHH,and PHH/MXene coatings,respectively)but also increased corrosion resistance(1857.850,42.357,1.593,and 0.085×10^(-6),A/cm^(2) for uncoated,pH,PHH,and PHH/MXene coatings,respectively).It has been proven that the in vitro bioactivity of PLA-HA coatings is further enhanced by adding HNT and MXene,along with SEM morphologies after SBF.Finally,2D lamellar MXene-filled coating exhibits antibacterial behavior against both E.coli and S.aureus bacteria.
基金support of the National Natural Science Foundation of China(Nos.52003248 and 82004001)the China Postdoctoral Science Foundation(Nos.2018M642780 and 2021T140613)+1 种基金the Open-ing Project of State Key Laboratory of Polymer Materials Engineer-ing(Sichuan University)(No.sklpme2019-4-31)the Key Research and Development and Promotion projects of Henan Province(No.202102210032)are gratefully acknowledged.
文摘Realizing all-day and all-weather energy-saving heating is crucial for mitigating the global energy and ecology crisis.Electric/solar heating are two promising heating approaches,yet materials with high elec-trical conductivity,high solar absorptivity,and low infrared emissivity at the same time are rare in na-ture,which are highly anticipated and of great significance for highly efficient electric/solar heating.In this work,we demonstrate that Ti_(3)C_(2)T_(x) MXene with low IR emissivity(14.5%)fills the gap in the absence of the above materials,exhibiting a remarkable electric/solar heating performance.The saturated heating temperature of Ti_(3)C_(2)T_(x) film reaches a record-high value of 201°C at a low driving voltage of 1.5 V,and reaches 84.3°C under practical solar irradiation(750 W/m^(2))with a high solar to the thermal conversion efficiency of 75.3%,which is far superior to other reported materials.Meanwhile,the low IR emissivity endows Ti_(3)C_(2)T_(x) with a remarkable passive radiative heating capability of 7.0°C,ensuring zero-energy heating without electric/solar energy supply.The intrinsic characteristic of high electrical conductivity,high solar absorptivity,and low IR emissivity makes Ti_(3)C_(2)T_(x) unique existence in nature,which is highly promising for all-day and all-weather energy-saving heating.
