Transition metal-based layered double hydroxides(LDHs)have been capable of working efficiently as catalysts in the basic oxygen evolution reaction(OER)for sustaining hydrogen production of alkaline water electrolysis....Transition metal-based layered double hydroxides(LDHs)have been capable of working efficiently as catalysts in the basic oxygen evolution reaction(OER)for sustaining hydrogen production of alkaline water electrolysis.Nevertheless,exploring new LDH-based electrocatalysts featuring both remarkable activity and good stability is still in high demand,which is pivotal for comprehensive understanding and impressive improvement of the sluggish OER kinetics.Here,a series of bimetallic(Co and Mo)LDH arrays were designed and fabricated via a facile and controlled strategy by incorporating a Mo source into presynthesized Co-based metal-organic framework(MOF)arrays on carbon cloth(CC),named as ZIF-67/CC arrays.We found that tuning the Mo content resulted in gradual differences in the structural properties,surface morphology,and chemical states of the resulting catalysts,namely CoMox-LDH/CC(x representing the added weight of the Mo source).Gratifyingly,the best-performing CoMo_(0.20)-LDH/CC electrocatalyst demonstrates a low overpotential of only 226 mV and high stability at a current density of 10 mA·cm^(−2),which is superior to most LDH-based OER catalysts reported previously.Furthermore,it only required 1.611 V voltage to drive the overall water splitting device at the current density of 10 mA·cm^(−2).The present study represents a significant advancement in the development and applications of new OER catalysts.展开更多
Layered double hydroxides(LDHs)with abundant accessible active sites are promising electrode materials for hybrid supercapacitor(HSC)due to their ultrahigh theoretical capacitances.However,the structural agglomeration...Layered double hydroxides(LDHs)with abundant accessible active sites are promising electrode materials for hybrid supercapacitor(HSC)due to their ultrahigh theoretical capacitances.However,the structural agglomeration of LDH leads to poor rate capability and durability.Herein,we construct a diffusion-controlled interface in hierarchical architecture of metal-organic framework(MOF)HKUST-1@cobalt-nickel LDH(denoted as HKUST-1@CoNiLDH)through an in situ etching/electro-deposition strategy.The rapid charge transfer and ionic diffusion in HKUST-1@CoNiLDH deliver a remarkable specific capacity of 297.23 mAh·g^(−1) at 1 A·g^(−1),superior to mostly reported LDH-based electrodes.More importantly,the as-prepared HKUST-1@CoNiLDH//activated carbon HSC exhibit a high energy density of 39.8 Wh·kg^(−1) at a power density of 799.9 W·kg^(−1) with an outstanding capacitance retention of 90%after 5,000 charge–discharge cycles.The in-depth understanding of the ionic diffusion among the MOF/LDH interfaces will greatly promote the further development of designing and synthesizing high performance energy conversion and storage devices.展开更多
In this study,we developed a novel confinement-synthesis approach to layered double hydroxide nanodots(LDH-NDs)anchored on carbon nanoparticles,which formed a three-dimensional(3D)interconnected network within a porou...In this study,we developed a novel confinement-synthesis approach to layered double hydroxide nanodots(LDH-NDs)anchored on carbon nanoparticles,which formed a three-dimensional(3D)interconnected network within a porous carbon support derived from pyrolysis of metal-organic frameworks(C-MOF).The resultant LDH-NDs@C-MOF nonprecious metal catalysts were demonstrated to exhibit super-high catalytic performance for oxygen evolution reaction(OER)with excellent operation stability and low overpotential(-230 mV)at an exchange current density of 10 mA·cm^(-2).The observed overpotential for the LDH-NDs@C-MOF is much lower than that of large-sized LDH nanosheets(321 mV),pure carbonized MOF(411 mV),and even commercial RuO_(2)(281 mV).X-ray absorption measurements and density functional theory(DFT)calculations revealed partial charge transfer from Fe^(3+)through an O bridge to Ni^(2+)at the edge of LDH-NDs supported by C-MOF to produce the optimal binding energies for OER intermediates.This,coupled with a large number of exposed active sides and efficient charge and electrolyte/reactant/product transports associated with the porous 3D C-MOF support,significantly boosted the OER performance of the LDH-ND catalyst with respect to its nanosheet counterpart.Apart from the fact that this is the first active side identification for LDH-ND OER catalysts,this work provides a general strategy to enhance activities of nanosheet catalysts by converting them into edge-rich nanodots to be supported by 3D porous carbon architectures.展开更多
Electrocatalytic oxygen evolution reaction(OER)is one of the important half reactions of electrocatalytic water splitting.However,the slow kinetic process involving four-electron transfer severely limits its reaction ...Electrocatalytic oxygen evolution reaction(OER)is one of the important half reactions of electrocatalytic water splitting.However,the slow kinetic process involving four-electron transfer severely limits its reaction efficiency,which in turn limits the overall electrocatalytic hydrolysis efficiency.In order to improve the activity of the electrocatalytic OER,researchers mainly update the catalyst from three aspects,that is,increase the conductivity of the electrocatalyst,and the quantity and quality of active sites.Twodimensional(2 D)engineering can effectively reduce the resistance of the materials and greatly increase the number of electrochemically active sites,while heterometal doping,or the bimetal strategy,can improve the quality of active sites via changing the electronic structure of the material.Thus,the combination of the two can enhance the activity of electrocatalytic OER in all three aspects:conductivity,number and quality of active sites.However,there is currently no review on this topic.Therefore,in this review,we summarize the application of bimetallic 2 D materials in electrocatalytic OER from four aspects:the structure,synthesis strategy,catalytic efficiency,and reaction mechanism.展开更多
基金the financial support of the Fundamental Research Funds for the Central Universities(No.40120631)the National Natural Science Foundation of China(No.52202291)for the support.+1 种基金C.C.acknowledges the financial support of Natural Science Foundation of Hubei Province(No.2022CFB388)the Natural Science Foundation of Hainan Province of China(No.623MS068).
文摘Transition metal-based layered double hydroxides(LDHs)have been capable of working efficiently as catalysts in the basic oxygen evolution reaction(OER)for sustaining hydrogen production of alkaline water electrolysis.Nevertheless,exploring new LDH-based electrocatalysts featuring both remarkable activity and good stability is still in high demand,which is pivotal for comprehensive understanding and impressive improvement of the sluggish OER kinetics.Here,a series of bimetallic(Co and Mo)LDH arrays were designed and fabricated via a facile and controlled strategy by incorporating a Mo source into presynthesized Co-based metal-organic framework(MOF)arrays on carbon cloth(CC),named as ZIF-67/CC arrays.We found that tuning the Mo content resulted in gradual differences in the structural properties,surface morphology,and chemical states of the resulting catalysts,namely CoMox-LDH/CC(x representing the added weight of the Mo source).Gratifyingly,the best-performing CoMo_(0.20)-LDH/CC electrocatalyst demonstrates a low overpotential of only 226 mV and high stability at a current density of 10 mA·cm^(−2),which is superior to most LDH-based OER catalysts reported previously.Furthermore,it only required 1.611 V voltage to drive the overall water splitting device at the current density of 10 mA·cm^(−2).The present study represents a significant advancement in the development and applications of new OER catalysts.
基金supported by the National Natural Science Foundation of China(No.22001156)the Youth Talent Fund of University Association for Science and Technology in Shaanxi,China(No.20210602)Science Foundation of Science and Technology Department of Shaanxi Province(No.2021JQ-533).
文摘Layered double hydroxides(LDHs)with abundant accessible active sites are promising electrode materials for hybrid supercapacitor(HSC)due to their ultrahigh theoretical capacitances.However,the structural agglomeration of LDH leads to poor rate capability and durability.Herein,we construct a diffusion-controlled interface in hierarchical architecture of metal-organic framework(MOF)HKUST-1@cobalt-nickel LDH(denoted as HKUST-1@CoNiLDH)through an in situ etching/electro-deposition strategy.The rapid charge transfer and ionic diffusion in HKUST-1@CoNiLDH deliver a remarkable specific capacity of 297.23 mAh·g^(−1) at 1 A·g^(−1),superior to mostly reported LDH-based electrodes.More importantly,the as-prepared HKUST-1@CoNiLDH//activated carbon HSC exhibit a high energy density of 39.8 Wh·kg^(−1) at a power density of 799.9 W·kg^(−1) with an outstanding capacitance retention of 90%after 5,000 charge–discharge cycles.The in-depth understanding of the ionic diffusion among the MOF/LDH interfaces will greatly promote the further development of designing and synthesizing high performance energy conversion and storage devices.
基金supported by The ARC(Nos.DP190103881 and FL190100126).
文摘In this study,we developed a novel confinement-synthesis approach to layered double hydroxide nanodots(LDH-NDs)anchored on carbon nanoparticles,which formed a three-dimensional(3D)interconnected network within a porous carbon support derived from pyrolysis of metal-organic frameworks(C-MOF).The resultant LDH-NDs@C-MOF nonprecious metal catalysts were demonstrated to exhibit super-high catalytic performance for oxygen evolution reaction(OER)with excellent operation stability and low overpotential(-230 mV)at an exchange current density of 10 mA·cm^(-2).The observed overpotential for the LDH-NDs@C-MOF is much lower than that of large-sized LDH nanosheets(321 mV),pure carbonized MOF(411 mV),and even commercial RuO_(2)(281 mV).X-ray absorption measurements and density functional theory(DFT)calculations revealed partial charge transfer from Fe^(3+)through an O bridge to Ni^(2+)at the edge of LDH-NDs supported by C-MOF to produce the optimal binding energies for OER intermediates.This,coupled with a large number of exposed active sides and efficient charge and electrolyte/reactant/product transports associated with the porous 3D C-MOF support,significantly boosted the OER performance of the LDH-ND catalyst with respect to its nanosheet counterpart.Apart from the fact that this is the first active side identification for LDH-ND OER catalysts,this work provides a general strategy to enhance activities of nanosheet catalysts by converting them into edge-rich nanodots to be supported by 3D porous carbon architectures.
基金the National Natural Science Foundation(NNSF)of China(Nos.21975162,51902208,51902209,22172099)the Natural Science Foundation of Guangdong(No.2020A1515010840)Shenzhen Science and Technology Program(Nos.JCYJ20200109105803806,RCYX20200714114535052,RCBS20200714114819161,JCYJ20190808111801674)。
文摘Electrocatalytic oxygen evolution reaction(OER)is one of the important half reactions of electrocatalytic water splitting.However,the slow kinetic process involving four-electron transfer severely limits its reaction efficiency,which in turn limits the overall electrocatalytic hydrolysis efficiency.In order to improve the activity of the electrocatalytic OER,researchers mainly update the catalyst from three aspects,that is,increase the conductivity of the electrocatalyst,and the quantity and quality of active sites.Twodimensional(2 D)engineering can effectively reduce the resistance of the materials and greatly increase the number of electrochemically active sites,while heterometal doping,or the bimetal strategy,can improve the quality of active sites via changing the electronic structure of the material.Thus,the combination of the two can enhance the activity of electrocatalytic OER in all three aspects:conductivity,number and quality of active sites.However,there is currently no review on this topic.Therefore,in this review,we summarize the application of bimetallic 2 D materials in electrocatalytic OER from four aspects:the structure,synthesis strategy,catalytic efficiency,and reaction mechanism.
