Lithium-sulfur(Li-S)batteries with high energy density and capacity have garnered significant research attention among various energy storage devices.However,the shuttle effect of polysulfides(LiPSs)remains a major ch...Lithium-sulfur(Li-S)batteries with high energy density and capacity have garnered significant research attention among various energy storage devices.However,the shuttle effect of polysulfides(LiPSs)remains a major challenge for their practical application.The design of battery separators has become a key aspect in addressing the challenge.MXenes,a promising two-dimensional(2D)material,offer exceptional conductivity,large surface area,high mechanical strength,and active sites for surface reactions.When assembled into layered films,MXenes form highly tunable two-dimensional channels ranging from a few angstroms to over 1 nm.These nanoconfined channels are instrumental in facilitating lithium-ion transport while effectively impeding the shuttle effect of LiPSs,which are essential for improving the specific capacity and cyclic stability of Li-S batteries.Substantial progress has been made in developing MXenes-based separators for Li-S batteries,yet there remains a research gap in summarizing advancements from the perspective of interlayer engineering.This entails maintaining the 2D nanochannels of layered MXenes-based separators while modulating the physicochemical environment within the MXenes interlayers through targeted modifications.This review highlights advancements in in situ modification of MXenes and their integration with 0D,1D,and 2D materials to construct laminated nanocomposite separators for Li-S batteries.The future development directions of MXenes-based materials in Li-S energy storage devices are also outlined,to drive further advancements in MXenes for Li-S battery separators.展开更多
MXenes,an innovative class of two-dimensional(2D)materials composed of transition-metal carbides and/or nitrides,have garnered significant interest for their potential in energy storage and conversion applications,whi...MXenes,an innovative class of two-dimensional(2D)materials composed of transition-metal carbides and/or nitrides,have garnered significant interest for their potential in energy storage and conversion applications,which is largely attributed to their modifiable surface terminations,exceptional conductivity,and favorable hydrophilic characteristics.MXenes show various ion transport behaviors in applications like electrochemical catalysis,supercapacitors,and batteries,encompassing processes like electrostatic adsorption of surface ions,redox reactions of ions,and interlayer ion shuttle.This review aims to present a summary of advancements in the comprehension of ion transport behaviors of Ti_(3)C_(2)T_(x)MXenes.First,the composition,properties,and synthesis techniques of MXenes are concisely summarized.Subsequently,the discussion delves into the mechanisms of ion transport in MXenes during CO_(2)reduction,water splitting,supercapacitor operation,and battery performance,elucidating the factors determining the electrochemical behaviors and efficacy.Furthermore,a compilation of strategies used to optimize ion transport behaviors in MXenes is presented.The article concludes by presenting the challenges and opportunities for these fields to facilitate the continued progress of MXenes in energy-related technologies.展开更多
Lithium-sulfur batteries(LSBs)hold significant promise as advanced energy storage systems due to their high energy density,low cost,and environmental advantages.However,despite recent advancements,their practical ener...Lithium-sulfur batteries(LSBs)hold significant promise as advanced energy storage systems due to their high energy density,low cost,and environmental advantages.However,despite recent advancements,their practical energy density still falls short of the levels required for commercial viability.The energy density is critically dependent on both sulfur loading and the amount of electrolyte used.Highsulfur loading coupled with lean electrolyte conditions presents several challenges,including the insulating nature of sulfur and Li_(2)S,insufficient electrolyte absorption,degradation of the cathode structure,severe lithium polysulfide shuttling,slow redox reaction kinetics,and instability of the Li metal anode.MXenes-based materials,with their metallic conductivity,large polar surfaces,and abundant active sites,have been identified as promising electrocatalysts to improve the redox reactions in LSBs.This review focuses on the significance and challenges associated with high-sulfur loading and lean electrolytes in LSBs,highlighting recent advancements in MXenes-based electrocatalysts aimed at optimizing sulfur cathodes and lithium anodes.It provides a comprehensive discussion on MXenes as both active materials and substrates in LSBs,with the goal of enhancing understanding of the regulatory mechanisms that govern sulfur conversion reactions and lithium plating/stripping behavior.Finally,the review explores future opportunities for MXenes-based electrocatalysts,paving the way for the practical application of LSBs.展开更多
Supercapacitors(SCs)stand out among various energy storage devices owing to their high power density and long-term cyc-ling stability.As new two-dimensional material,MXenes have become a research hotspot in recent yea...Supercapacitors(SCs)stand out among various energy storage devices owing to their high power density and long-term cyc-ling stability.As new two-dimensional material,MXenes have become a research hotspot in recent years owing to their unique structure and rich surface functional groups.Compared with other materials,MXenes are more promising for SCs owing to their tunable precurs-ors,structural stability,and excellent electrical conductivity.However,the rate performance and electrochemical reaction activity of MXene materials are poor,and stacking severely limits their application.Therefore,various modification strategies are employed to im-prove the electrochemical performance of MXene materials.As the modification strategy of MXene electrode materials often involves in-creasing the number of ion transport channels to expose more active sites,the packing density is also affected to different degrees.There-fore,achieving a balance between high volumetric capacitance and rapid ion transport has become a key issue for the application of MXene-based SCs in wearable devices and microdevices.In this paper,the latest progress in the preparation methods and modification strategies of MXenes in recent years is reviewed with the aim of achieving both high volumetric capacitance and high ion transport for ex-panding the application of MXene-based SCs in microdevices and wearable devices.展开更多
Two-dimensional(2D)transition metal carbides and/or nitrides(MXenes)have exhibited many outstanding merits,including good conductivity,tunable bandgap,high electric capacity and optical transparency[1,2].In the past s...Two-dimensional(2D)transition metal carbides and/or nitrides(MXenes)have exhibited many outstanding merits,including good conductivity,tunable bandgap,high electric capacity and optical transparency[1,2].In the past several years,MXenes have shown promising advantages in the fields of energy storage,electrocatalysis,electromagnetic shielding,and(opto-)electronic devices.These excellent properties can be tuned by controlling the chemical composition,shape and size of the nanosheets,defects,boundaries,and surface functional groups,etc.展开更多
Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast pho...Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast photogenerated electron-hole recombination.To tackle these issues,herein,we propose a new strategy to modify Cd_(x) Zn_(1-x) S nanoreactors by the simultaneous utilization of ionic-liquid-assisted morphology engineering and MXene-incorporating method.That is,we designed and synthesized a novel hierarchi-cal Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction composite through the in-situ deposition of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets on unique IL-modified Ti_(3) C_(2) MXenes by a one-pot solvothermal method for efficiently PHE.The unique construction strategy tailors the thickness of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets and prevents them from stacking and agglomeration,and especially,optimizes their charge transfer pathways during the photocatalytic process.Compared with pristine Cd_(0.8) Zn_(0.2) S nanosheets,Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) has abun-dant photogenerated electrons available on the Ti_(3) C_(2) surface for proton reduction reaction,owing to the absence of deep-trapped electrons,suppression of electron-hole recombination in Cd_(0.8) Zn_(0.2) S and high-efficiency charge separation at the Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction interface.Moreover,the hy-drophilicity,electrical conductivity,visible-light absorption capacity,and surficial hydrogen desorption of Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) heterostructure are significantly improved.As a result,the heterostructure exhibits out-standing photocatalytic stability and super high apparent quantum efficiency,being rendered as one of the best noble-metal-free Cd-Zn-S-based photocatalysts.This work illustrates the mechanisms of mor-phology control and heterojunction construction in controlling the catalytic behavior of photocatalysts and highlights the great potential of the IL-assisted route in the synthesis of high-performance MXene-based heterostructures for photocatalytic hydrogen evolution.展开更多
As a novel two-dimensional(2D)material,MXenes are anticipated to have a significant impact on future aqueous energy storage and conversion technologies owing to their unique intrinsic laminar structure and exceptional...As a novel two-dimensional(2D)material,MXenes are anticipated to have a significant impact on future aqueous energy storage and conversion technologies owing to their unique intrinsic laminar structure and exceptional physicochemical properties.Nevertheless,the fabrication and utilization of functional MXenebased devices face formidable challenges due to their susceptibility to oxidative degradation in aqueous solutions.This review begins with an outline of various preparation techniques for MXenes and their implications for structure and surface chemistry.Subsequently,the controversial oxidation mechanisms are discussed,followed by a summary of currently employed oxidation characterization techniques.Additionally,the factors influencing MXene oxidation are then introduced,encompassing chemical composition(types of M,X elements,layer numbers,terminations,and defects)as well as environment(atmosphere,temperature,light,potential,solution pH,free water and O_(2)content).The review then shifts its focus to strategies aiming to prevent or delay MXene oxidation,thereby expanding the applicability of MXenes in complex environments.Finally,the challenges and prospects within this rapidly-growing research field are presented to promote further advancements of MXenes in aqueous storage systems.展开更多
Emerging two-dimensional MXenes have been extensively studied in a wide range of fields thanks to their superior electrical and hydrophilic attributes as well as excellent chemical stability and mechanical flexibility...Emerging two-dimensional MXenes have been extensively studied in a wide range of fields thanks to their superior electrical and hydrophilic attributes as well as excellent chemical stability and mechanical flexibility.Among them,the ultrahigh electrical conductivity(σ)and tunable band structures of benchmark Ti_(3)C_(2)T_(x) MXene demonstrate its good potential as thermoelectric(TE)materials.However,both the large variation ofσreported in the literature and the intrinsically low Seebeck coefficient(S)hinder the practical applications.Herein,this study has for the first time systematically investigated the TE properties of neat Ti_(3)C_(2)T_(x) films,which are finely modulated by exploiting different dispersing solvents,controlling nanosheet sizes and constructing composites.First,deionized water is found to be superior for obtaining closely packed MXene sheets relative to other polar solvents.Second,a simultaneous increase in both S andσis realized via elevating centrifugal speed on MXene aqueous suspensions to obtain small-sized nanosheets,thus yielding an ultrahigh power factor up to~156μW m^(-1) K^(-2).Third,S is significantly enhanced yet accompanied by a reduction inσwhen constructing MXene-based nanocomposites,the latter of which is originated from the damage to the intimate stackings of MXene nanosheets.Together,a correlation between the TE properties of neat Ti_(3)C_(2)T_(x) films and the stacking of nanosheets is elucidated,which would stimulate further exploration of MXene TEs.展开更多
Transition metal carbides,known as MXenes,particularly Ti_(3)C_(2)T_(x),have been extensively explored as promising materials for electrochemical reactions.However,transition metal carbonitride MXenes with high nitrog...Transition metal carbides,known as MXenes,particularly Ti_(3)C_(2)T_(x),have been extensively explored as promising materials for electrochemical reactions.However,transition metal carbonitride MXenes with high nitrogen content for electrochemical reactions are rarely reported.In this work,transition metal carbonitride MXenes incorporated with Pt-based electrocatalysts,ranging from single atoms to sub-nanometer dimensions,are explored for hydrogen evolution reaction(HER).The fabricated Pt clusters/MXene catalyst exhibits superior HER performance compared to the single-atom-incorporated MXene and commercial Pt/C catalyst in both acidic and alkaline electrolytes.The optimized sample shows low overpotentials of 28,65,and 154 mV at a current densities of 10,100,and 500 m A cm^(-2),a small Tafel slope of 29 m V dec^(-1),a high mass activity of 1203 mA mgPt^(-1)and an excellent turnover frequency of 6.1 s^(-1)in the acidic electrolyte.Density functional theory calculations indicate that this high performance can be attributed to the enhanced active sites,increased surface functional groups,faster charge transfer dynamics,and stronger electronic interaction between Pt and MXene,resulting in optimized hydrogen absorption/desorption toward better HER.This work demonstrates that MXenes with a high content of nitrogen may be promising candidates for various catalytic reactions by incorporating single atoms or clusters.展开更多
The electrochemical reduction reaction of carbon dioxide(CO_(2)-ERR)holds tremendous potential as a key approach for achieving carbon neutrality by harnessing renewable resources.However,the current state of CO_(2)-ER...The electrochemical reduction reaction of carbon dioxide(CO_(2)-ERR)holds tremendous potential as a key approach for achieving carbon neutrality by harnessing renewable resources.However,the current state of CO_(2)-ERR encounters challenges in terms of efficiency and selectivity.Overcoming these obstacles requires the development of a robust electrocatalyst capable of enhancing process efficiency and improving selectivity towards desired products.In recent years,2D materials have garnered significant attention as efficient catalysts.Among them,MXene stands out of high interest due to unique multilayered structure and presence of surface functional moieties.The MXene material offers high electrical conductivity,versatile surface chemistry,and tunable interface designs.This comprehensive review explores the utilization of MXene-based catalysts for CO_(2)-ERR into valuable products.It covers fundamental aspects of electrochemical conversion,including CO_(2)adsorption on MXene Ti_(3)C_(2)T_(x),the mechanism of CO_(2)-ERR on MXene(Mo_(2)CS_(2))single-atom catalysts,applications,synthesis methods of MXene production,and future prospects.Additionally,the review highlights the significance of modern artificial intelligence techniques,particularly machine learning,in screening and activating CO_(2),making it a pioneering scientific endeavor.展开更多
Hybrid electrochemical devices(HEDs),which consist of one faradaic electrode and the other capacitive electrode,are considered as promising technologies owing to their high ion storage capacity,excellent rate performa...Hybrid electrochemical devices(HEDs),which consist of one faradaic electrode and the other capacitive electrode,are considered as promising technologies owing to their high ion storage capacity,excellent rate performance,and long cyclability.In particular,MXenes have been extensively investigated as faradaic electrodes of HEDs owing to their fast electron and ion transport capabilities and diverse and tunable surface modifications.Herein,we provide a comprehensive review on the design strategies for enhancing the electrochemical performances of MXenes in HEDs,focusing on interlayer engineering,surface modification,and hybrid formation.We also summarize the recent advancement in the use of MXenes in metal-ion hybrid capacitors and hybrid capacitive deionization.Lastly,we address the current challenges for the practical application of MXene-based hybrid devices and offer our perspectives for future research directions.This review aims to provide insights into innovative MXene design strategies for electrochemical energy storage and water purification by elucidating the correlations between material chemistry and electrochemical properties of MXenes.展开更多
MXenes,the most recent addition to the 2D material family,have attracted significant attention owing to their distinctive characteristics,including high surface area,conductivity,surface characteristics,mechanical str...MXenes,the most recent addition to the 2D material family,have attracted significant attention owing to their distinctive characteristics,including high surface area,conductivity,surface characteristics,mechanical strength,etc.This review begins by presenting MXenes,providing insights into their structural characteristics,synthesis methods,and surface functional groups.The review covers a thorough analysis of MXene surface properties,including surface chemistry and termination group impacts.The properties of MXenes are influenced by their synthesis,which can be fluorine-based or fluorinedependent.Fluorine-based synthesis techniques involve etching with fluorine-based reagents,mainly including HF or LiF/HCl,while fluorine-free methods include electrochemical etching,chemical vapor deposition(CVD),alkaline etching,Lewis acid-based etching,etc.These techniques result in the emergence of functional groups such as-F,-O,-OH,-Cl,etc.on the MXenes surface,depending on the synthesis method used.Properties of MXenes,such as electrical conductivity,electronic properties,catalytic activity,magnetic properties,mechanical strength,and chemical and thermal stability,are examined,and the role of functional groups in determining these properties is explored.The review delves into the diverse applications of MXenes,encompassing supercapacitors,battery materials,hydrogen storage,fuel cells,electromagnetic interference(EMI) shielding,pollutant removal,water purification,flexible electronics,sensors,additive manufacturing,catalysis,biomedical and healthcare fields,etc.Finally,this article outlines the challenges and opportunities in the current and future development of MXenes research,addressing various aspects such as synthesis scalability,etching challenges,and multifunctionality,and exploring novel applications.The review concludes with future prospects and conclusions envisioning the impact of MXenes on future technologies and innovation.展开更多
基金supported by Beijing Natural Science Foundation(Nos.2232037 and 2242035)the National Natural Science Foundation of China(Nos.22005012,22105012 and 51803183)+1 种基金Chunhui Plan Cooperative Project of Ministry of Education(No.202201298)the China Postdoctoral Science Foundation Funded Project(No.2023M733520).
文摘Lithium-sulfur(Li-S)batteries with high energy density and capacity have garnered significant research attention among various energy storage devices.However,the shuttle effect of polysulfides(LiPSs)remains a major challenge for their practical application.The design of battery separators has become a key aspect in addressing the challenge.MXenes,a promising two-dimensional(2D)material,offer exceptional conductivity,large surface area,high mechanical strength,and active sites for surface reactions.When assembled into layered films,MXenes form highly tunable two-dimensional channels ranging from a few angstroms to over 1 nm.These nanoconfined channels are instrumental in facilitating lithium-ion transport while effectively impeding the shuttle effect of LiPSs,which are essential for improving the specific capacity and cyclic stability of Li-S batteries.Substantial progress has been made in developing MXenes-based separators for Li-S batteries,yet there remains a research gap in summarizing advancements from the perspective of interlayer engineering.This entails maintaining the 2D nanochannels of layered MXenes-based separators while modulating the physicochemical environment within the MXenes interlayers through targeted modifications.This review highlights advancements in in situ modification of MXenes and their integration with 0D,1D,and 2D materials to construct laminated nanocomposite separators for Li-S batteries.The future development directions of MXenes-based materials in Li-S energy storage devices are also outlined,to drive further advancements in MXenes for Li-S battery separators.
基金Yongjiang Innovative Individual Introduction of ChinaNingbo Top-talent Team Program,Program for the National Natural Science Foundation of ChinaChina Postdoctoral Science Foundation,Grant/Award Numbers:2022M723253,2023M733597。
文摘MXenes,an innovative class of two-dimensional(2D)materials composed of transition-metal carbides and/or nitrides,have garnered significant interest for their potential in energy storage and conversion applications,which is largely attributed to their modifiable surface terminations,exceptional conductivity,and favorable hydrophilic characteristics.MXenes show various ion transport behaviors in applications like electrochemical catalysis,supercapacitors,and batteries,encompassing processes like electrostatic adsorption of surface ions,redox reactions of ions,and interlayer ion shuttle.This review aims to present a summary of advancements in the comprehension of ion transport behaviors of Ti_(3)C_(2)T_(x)MXenes.First,the composition,properties,and synthesis techniques of MXenes are concisely summarized.Subsequently,the discussion delves into the mechanisms of ion transport in MXenes during CO_(2)reduction,water splitting,supercapacitor operation,and battery performance,elucidating the factors determining the electrochemical behaviors and efficacy.Furthermore,a compilation of strategies used to optimize ion transport behaviors in MXenes is presented.The article concludes by presenting the challenges and opportunities for these fields to facilitate the continued progress of MXenes in energy-related technologies.
基金supported by the Research Funding of Hangzhou International Innovation Institute of Beihang University(Grant No.2024KQ102 and 2024KQ131)the National Natural Science Foundation of China(Grant No.524B2020,51925202,U22A20141,52432004,U23A20575,52472183,and 22379039).
文摘Lithium-sulfur batteries(LSBs)hold significant promise as advanced energy storage systems due to their high energy density,low cost,and environmental advantages.However,despite recent advancements,their practical energy density still falls short of the levels required for commercial viability.The energy density is critically dependent on both sulfur loading and the amount of electrolyte used.Highsulfur loading coupled with lean electrolyte conditions presents several challenges,including the insulating nature of sulfur and Li_(2)S,insufficient electrolyte absorption,degradation of the cathode structure,severe lithium polysulfide shuttling,slow redox reaction kinetics,and instability of the Li metal anode.MXenes-based materials,with their metallic conductivity,large polar surfaces,and abundant active sites,have been identified as promising electrocatalysts to improve the redox reactions in LSBs.This review focuses on the significance and challenges associated with high-sulfur loading and lean electrolytes in LSBs,highlighting recent advancements in MXenes-based electrocatalysts aimed at optimizing sulfur cathodes and lithium anodes.It provides a comprehensive discussion on MXenes as both active materials and substrates in LSBs,with the goal of enhancing understanding of the regulatory mechanisms that govern sulfur conversion reactions and lithium plating/stripping behavior.Finally,the review explores future opportunities for MXenes-based electrocatalysts,paving the way for the practical application of LSBs.
基金supported by the National Natural Science Foundation of China(No.52272242)the Provisional Key Research and Development Program of Henan Province,China(No.231111240600)+1 种基金the Natural Science Foundation of Henan Province,China(No.242300421428)the Start-up Funding for Scientific Research of Zhengzhou University,China(No.32310221).
文摘Supercapacitors(SCs)stand out among various energy storage devices owing to their high power density and long-term cyc-ling stability.As new two-dimensional material,MXenes have become a research hotspot in recent years owing to their unique structure and rich surface functional groups.Compared with other materials,MXenes are more promising for SCs owing to their tunable precurs-ors,structural stability,and excellent electrical conductivity.However,the rate performance and electrochemical reaction activity of MXene materials are poor,and stacking severely limits their application.Therefore,various modification strategies are employed to im-prove the electrochemical performance of MXene materials.As the modification strategy of MXene electrode materials often involves in-creasing the number of ion transport channels to expose more active sites,the packing density is also affected to different degrees.There-fore,achieving a balance between high volumetric capacitance and rapid ion transport has become a key issue for the application of MXene-based SCs in wearable devices and microdevices.In this paper,the latest progress in the preparation methods and modification strategies of MXenes in recent years is reviewed with the aim of achieving both high volumetric capacitance and high ion transport for ex-panding the application of MXene-based SCs in microdevices and wearable devices.
文摘Two-dimensional(2D)transition metal carbides and/or nitrides(MXenes)have exhibited many outstanding merits,including good conductivity,tunable bandgap,high electric capacity and optical transparency[1,2].In the past several years,MXenes have shown promising advantages in the fields of energy storage,electrocatalysis,electromagnetic shielding,and(opto-)electronic devices.These excellent properties can be tuned by controlling the chemical composition,shape and size of the nanosheets,defects,boundaries,and surface functional groups,etc.
基金financial supports pro-vided by the National Natural Science Foundation of China(No.21905279)the Natural Science Foundation of Fujian Province(No.2020J05086).
文摘Small-sized Cd_(x) Zn_(1-x) S solid solution nanomaterial is an important candidate for efficient photocatalytic hydrogen evolution(PHE),but it still suffers from easy agglomeration,severe photo corrosion,and fast photogenerated electron-hole recombination.To tackle these issues,herein,we propose a new strategy to modify Cd_(x) Zn_(1-x) S nanoreactors by the simultaneous utilization of ionic-liquid-assisted morphology engineering and MXene-incorporating method.That is,we designed and synthesized a novel hierarchi-cal Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction composite through the in-situ deposition of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets on unique IL-modified Ti_(3) C_(2) MXenes by a one-pot solvothermal method for efficiently PHE.The unique construction strategy tailors the thickness of ultrathin Cd_(0.8) Zn_(0.2) S nanosheets and prevents them from stacking and agglomeration,and especially,optimizes their charge transfer pathways during the photocatalytic process.Compared with pristine Cd_(0.8) Zn_(0.2) S nanosheets,Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) has abun-dant photogenerated electrons available on the Ti_(3) C_(2) surface for proton reduction reaction,owing to the absence of deep-trapped electrons,suppression of electron-hole recombination in Cd_(0.8) Zn_(0.2) S and high-efficiency charge separation at the Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) Schottky junction interface.Moreover,the hy-drophilicity,electrical conductivity,visible-light absorption capacity,and surficial hydrogen desorption of Cd_(0.8) Zn_(0.2) S/Ti_(3) C_(2) heterostructure are significantly improved.As a result,the heterostructure exhibits out-standing photocatalytic stability and super high apparent quantum efficiency,being rendered as one of the best noble-metal-free Cd-Zn-S-based photocatalysts.This work illustrates the mechanisms of mor-phology control and heterojunction construction in controlling the catalytic behavior of photocatalysts and highlights the great potential of the IL-assisted route in the synthesis of high-performance MXene-based heterostructures for photocatalytic hydrogen evolution.
基金supported by the Fundamental Research Funds for the Central Universities(No.2042023kf0094)the National Key Research and Development Program of China(No.2022YFA1502902)the National Natural Science Foundation of China(No.22101217).
文摘As a novel two-dimensional(2D)material,MXenes are anticipated to have a significant impact on future aqueous energy storage and conversion technologies owing to their unique intrinsic laminar structure and exceptional physicochemical properties.Nevertheless,the fabrication and utilization of functional MXenebased devices face formidable challenges due to their susceptibility to oxidative degradation in aqueous solutions.This review begins with an outline of various preparation techniques for MXenes and their implications for structure and surface chemistry.Subsequently,the controversial oxidation mechanisms are discussed,followed by a summary of currently employed oxidation characterization techniques.Additionally,the factors influencing MXene oxidation are then introduced,encompassing chemical composition(types of M,X elements,layer numbers,terminations,and defects)as well as environment(atmosphere,temperature,light,potential,solution pH,free water and O_(2)content).The review then shifts its focus to strategies aiming to prevent or delay MXene oxidation,thereby expanding the applicability of MXenes in complex environments.Finally,the challenges and prospects within this rapidly-growing research field are presented to promote further advancements of MXenes in aqueous storage systems.
基金supported by the China Postdoctoral Science Foundation(grant No.2024M750511,J.T.)National Key R&D Program of China(grant No.2022YFB3603804,Y.Z.)National Natural Science Foundation of China(NSFC)under grant Nos.82172470(C.X.)and 22375050(Z.L.).
文摘Emerging two-dimensional MXenes have been extensively studied in a wide range of fields thanks to their superior electrical and hydrophilic attributes as well as excellent chemical stability and mechanical flexibility.Among them,the ultrahigh electrical conductivity(σ)and tunable band structures of benchmark Ti_(3)C_(2)T_(x) MXene demonstrate its good potential as thermoelectric(TE)materials.However,both the large variation ofσreported in the literature and the intrinsically low Seebeck coefficient(S)hinder the practical applications.Herein,this study has for the first time systematically investigated the TE properties of neat Ti_(3)C_(2)T_(x) films,which are finely modulated by exploiting different dispersing solvents,controlling nanosheet sizes and constructing composites.First,deionized water is found to be superior for obtaining closely packed MXene sheets relative to other polar solvents.Second,a simultaneous increase in both S andσis realized via elevating centrifugal speed on MXene aqueous suspensions to obtain small-sized nanosheets,thus yielding an ultrahigh power factor up to~156μW m^(-1) K^(-2).Third,S is significantly enhanced yet accompanied by a reduction inσwhen constructing MXene-based nanocomposites,the latter of which is originated from the damage to the intimate stackings of MXene nanosheets.Together,a correlation between the TE properties of neat Ti_(3)C_(2)T_(x) films and the stacking of nanosheets is elucidated,which would stimulate further exploration of MXene TEs.
基金the final support of ARC DP220103045the startup support of KFUPMPrince Sultan University for their support。
文摘Transition metal carbides,known as MXenes,particularly Ti_(3)C_(2)T_(x),have been extensively explored as promising materials for electrochemical reactions.However,transition metal carbonitride MXenes with high nitrogen content for electrochemical reactions are rarely reported.In this work,transition metal carbonitride MXenes incorporated with Pt-based electrocatalysts,ranging from single atoms to sub-nanometer dimensions,are explored for hydrogen evolution reaction(HER).The fabricated Pt clusters/MXene catalyst exhibits superior HER performance compared to the single-atom-incorporated MXene and commercial Pt/C catalyst in both acidic and alkaline electrolytes.The optimized sample shows low overpotentials of 28,65,and 154 mV at a current densities of 10,100,and 500 m A cm^(-2),a small Tafel slope of 29 m V dec^(-1),a high mass activity of 1203 mA mgPt^(-1)and an excellent turnover frequency of 6.1 s^(-1)in the acidic electrolyte.Density functional theory calculations indicate that this high performance can be attributed to the enhanced active sites,increased surface functional groups,faster charge transfer dynamics,and stronger electronic interaction between Pt and MXene,resulting in optimized hydrogen absorption/desorption toward better HER.This work demonstrates that MXenes with a high content of nitrogen may be promising candidates for various catalytic reactions by incorporating single atoms or clusters.
基金supported by the National Natural Science Foundation of China(Nos.62375200 and 61975148).
文摘The electrochemical reduction reaction of carbon dioxide(CO_(2)-ERR)holds tremendous potential as a key approach for achieving carbon neutrality by harnessing renewable resources.However,the current state of CO_(2)-ERR encounters challenges in terms of efficiency and selectivity.Overcoming these obstacles requires the development of a robust electrocatalyst capable of enhancing process efficiency and improving selectivity towards desired products.In recent years,2D materials have garnered significant attention as efficient catalysts.Among them,MXene stands out of high interest due to unique multilayered structure and presence of surface functional moieties.The MXene material offers high electrical conductivity,versatile surface chemistry,and tunable interface designs.This comprehensive review explores the utilization of MXene-based catalysts for CO_(2)-ERR into valuable products.It covers fundamental aspects of electrochemical conversion,including CO_(2)adsorption on MXene Ti_(3)C_(2)T_(x),the mechanism of CO_(2)-ERR on MXene(Mo_(2)CS_(2))single-atom catalysts,applications,synthesis methods of MXene production,and future prospects.Additionally,the review highlights the significance of modern artificial intelligence techniques,particularly machine learning,in screening and activating CO_(2),making it a pioneering scientific endeavor.
基金supported by the National Research Foundation of Korea(NRF),funded by the Ministry of Science and ICT(Grant No.RS-2023-00217581),Republic of Korea。
文摘Hybrid electrochemical devices(HEDs),which consist of one faradaic electrode and the other capacitive electrode,are considered as promising technologies owing to their high ion storage capacity,excellent rate performance,and long cyclability.In particular,MXenes have been extensively investigated as faradaic electrodes of HEDs owing to their fast electron and ion transport capabilities and diverse and tunable surface modifications.Herein,we provide a comprehensive review on the design strategies for enhancing the electrochemical performances of MXenes in HEDs,focusing on interlayer engineering,surface modification,and hybrid formation.We also summarize the recent advancement in the use of MXenes in metal-ion hybrid capacitors and hybrid capacitive deionization.Lastly,we address the current challenges for the practical application of MXene-based hybrid devices and offer our perspectives for future research directions.This review aims to provide insights into innovative MXene design strategies for electrochemical energy storage and water purification by elucidating the correlations between material chemistry and electrochemical properties of MXenes.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(NRF-2020R1A6A1A03043435 and 2020R1A2C1099862)supported by the Korea Institute for Advancement of Technology(KIAT)grant funded by the Korean Government(MOTIE)(P0012451,The Competency Development Program for Industry Specialist)。
文摘MXenes,the most recent addition to the 2D material family,have attracted significant attention owing to their distinctive characteristics,including high surface area,conductivity,surface characteristics,mechanical strength,etc.This review begins by presenting MXenes,providing insights into their structural characteristics,synthesis methods,and surface functional groups.The review covers a thorough analysis of MXene surface properties,including surface chemistry and termination group impacts.The properties of MXenes are influenced by their synthesis,which can be fluorine-based or fluorinedependent.Fluorine-based synthesis techniques involve etching with fluorine-based reagents,mainly including HF or LiF/HCl,while fluorine-free methods include electrochemical etching,chemical vapor deposition(CVD),alkaline etching,Lewis acid-based etching,etc.These techniques result in the emergence of functional groups such as-F,-O,-OH,-Cl,etc.on the MXenes surface,depending on the synthesis method used.Properties of MXenes,such as electrical conductivity,electronic properties,catalytic activity,magnetic properties,mechanical strength,and chemical and thermal stability,are examined,and the role of functional groups in determining these properties is explored.The review delves into the diverse applications of MXenes,encompassing supercapacitors,battery materials,hydrogen storage,fuel cells,electromagnetic interference(EMI) shielding,pollutant removal,water purification,flexible electronics,sensors,additive manufacturing,catalysis,biomedical and healthcare fields,etc.Finally,this article outlines the challenges and opportunities in the current and future development of MXenes research,addressing various aspects such as synthesis scalability,etching challenges,and multifunctionality,and exploring novel applications.The review concludes with future prospects and conclusions envisioning the impact of MXenes on future technologies and innovation.
