A mechanochemical redox reaction between KMnO4 and CoCl2 was developed to obtain a CoxMn1-xOy catalyst with a specific surface area of 479 m^2 g^-1,which was higher than that obtained using a co-precipitation(CP)metho...A mechanochemical redox reaction between KMnO4 and CoCl2 was developed to obtain a CoxMn1-xOy catalyst with a specific surface area of 479 m^2 g^-1,which was higher than that obtained using a co-precipitation(CP)method(34 m2 g^-1),sol-gel(SG)method(72 m^2 g^-1),or solution redox process(131 m^2 g^-1).During catalytic combustion,this CoxMn1-xOy catalyst exhibited better activity(T100 for propylene=~200℃)than the control catalysts obtained using the SG(325℃)or CP(450℃)methods.The mechanical action,mainly in the form of kinetic energy and frictional heating,may generate a high degree of interstitial porosity,while the redox reaction could contribute to good dispersion of cobalt and manganese species.Moreover,the as-prepared CoxMn1-xOy catalyst worked well in the presence of water vapor(H2O 4.2%,>60 h)or SO2(100 ppm)and at high temperature(400℃,>60 h).The structure MnO2·(CoOOH)2.93 was suggested for the current CoxMn1-xOy catalyst.This catalyst could be extended to the total oxidation of other typical hydrocarbons(T90=150°C for ethanol,T90=225°C for acetone,T90=250℃for toluene,T90=120℃for CO,and T90=540℃for CH4).Scale-up of the synthesis of CoxMn1-xOy catalyst(1 kg)can be achieved via ball milling,which may provide a potential strategy for real world catalysis.展开更多
The electrochemical carbon dioxide reduction reaction(CO_(2)RR),which can produce value-added chemical feedstocks,is a proton-coupled-electron process with sluggish kinetics.Thus,highly efficient,cheap catalysts are u...The electrochemical carbon dioxide reduction reaction(CO_(2)RR),which can produce value-added chemical feedstocks,is a proton-coupled-electron process with sluggish kinetics.Thus,highly efficient,cheap catalysts are urgently required.Transition metal oxides such as CoO_(x),FeO_(x),and NiO_(x)are low-cost,low toxicity,and abundant materials for a wide range of electrochemical reactions,but are almost inert for CO_(2)RR.Here,we report for the first time that nitrogen doped carbon nanotubes(N-CNT)have a surprising activation effect on the activity and selectivity of transition metal-oxide(MO_(x)where M=Fe,Ni,and Co)nanoclusters for CO_(2)RR.MO_(x)supported on N-CNT,MO_(x)/N-CNT,achieves a CO yield of 2.6–2.8 mmol cm−2 min−1 at an overpotential of−0.55 V,which is two orders of magnitude higher than MO_(x)supported on acid treated CNTs(MO_(x)/O-CNT)and four times higher than pristine N-CNT.The faraday efficiency for electrochemical CO_(2)-to-CO conversion is as high as 90.3%at overpotential of 0.44 V.Both in-situ XAS measurements and DFT calculations disclose that MO_(x)nanoclusters can be hydrated in CO_(2)saturated KHCO_(3),and the N defects of N-CNT effectively stabilize these metal hydroxyl species under carbon dioxide reduction reaction conditions,which can split the water molecules and provide local protons to inhibit the poisoning of active sites under carbon dioxide reduction reaction conditions.展开更多
Regulating the selectivity toward a target hydrocarbon product is still the focus of CO_(2)electroreduction.Here,we discover that the original surface Cu species in Cu gas-diffusion electrodes plays a more important r...Regulating the selectivity toward a target hydrocarbon product is still the focus of CO_(2)electroreduction.Here,we discover that the original surface Cu species in Cu gas-diffusion electrodes plays a more important role than the surface roughness,local pH,and facet in governing the selectivity toward C_(1)or C_(2)hydrocarbons.The selectivity toward C_(2)H_(4) progressively increases,while CH_(4) decreases steadily upon lowering the Cu oxidation species fraction.At a relatively low electrodeposition voltage of 1.5 V,the Cu gas-diffusion electrode with the highest Cu^(δ+)/Cu^(0)ratio favors the pathways of∗CO hydrogenation to form CH_(4) with maximum Faradaic efficiency of 65.4%and partial current density of 228 mA cm^(−2)at−0.83 V vs RHE.At 2.0 V,the Cu gas-diffusion electrode with the lowest Cu^(δ+)/Cu^(0)ratio prefers C-C coupling to form C_(2)+products with Faradaic efficiency topping 80.1%at−0.75 V vs RHE,where the Faradaic efficiency of C_(2)H_(4) accounts for 46.4%and the partial current density of C_(2)H_(4) achieves 279 mA cm^(−2).This work demonstrates that the selectivity from CH_(4) to C_(2)H_(4) is switchable by tuning surface Cu species composition of Cu gas-diffusion electrodes.展开更多
With the current integration of distributed energy resources into the grid,the structure of distribution networks is becoming more complex.This complexity significantly expands the solution space in the optimization p...With the current integration of distributed energy resources into the grid,the structure of distribution networks is becoming more complex.This complexity significantly expands the solution space in the optimization process for network reconstruction using intelligent algorithms.Consequently,traditional intelligent algorithms frequently encounter insufficient search accuracy and become trapped in local optima.To tackle this issue,a more advanced particle swarm optimization algorithm is proposed.To address the varying emphases at different stages of the optimization process,a dynamic strategy is implemented to regulate the social and self-learning factors.The Metropolis criterion is introduced into the simulated annealing algorithm to occasionally accept suboptimal solutions,thereby mitigating premature convergence in the population optimization process.The inertia weight is adjusted using the logistic mapping technique to maintain a balance between the algorithm’s global and local search abilities.The incorporation of the Pareto principle involves the consideration of network losses and voltage deviations as objective functions.A fuzzy membership function is employed for selecting the results.Simulation analysis is carried out on the restructuring of the distribution network,using the IEEE-33 node system and the IEEE-69 node system as examples,in conjunction with the integration of distributed energy resources.The findings demonstrate that,in comparison to other intelligent optimization algorithms,the proposed enhanced algorithm demonstrates a shorter convergence time and effectively reduces active power losses within the network.Furthermore,it enhances the amplitude of node voltages,thereby improving the stability of distribution network operations and power supply quality.Additionally,the algorithm exhibits a high level of generality and applicability.展开更多
Opto–electromechanical coupling at the nanoscale is an important topic in new scientific studies and technical applications. In this work, the optically manipulated electromechanical behaviors of individual cadmium s...Opto–electromechanical coupling at the nanoscale is an important topic in new scientific studies and technical applications. In this work, the optically manipulated electromechanical behaviors of individual cadmium sulfide(CdS) nanowires are investigated by a customer-built optical holder inside transmission electron microscope, wherein in situ electromechanical resonance took place in conjunction with photo excitation. It is found that the natural resonance frequency of the nanowire under illumination becomes considerably lower than that under darkness. This redshift effect is closely related to the wavelength of the applied light and the diameter of the nanowires. Density functional theory(DFT) calculation shows that the photoexcitation leads to the softening of CdS nanowires and thus the redshift of natural frequency, which is in agreement with the experimental results.展开更多
The development of highly potential electrocatalysts for acidic water electrolysis is particularly desirable for many energy‐related processes.Herein,we demonstrated a versatile strategy to activate and stabilize RuO...The development of highly potential electrocatalysts for acidic water electrolysis is particularly desirable for many energy‐related processes.Herein,we demonstrated a versatile strategy to activate and stabilize RuO_(2)‐based electrocatalyst for acidic water splitting by a trace of Pt,where Pt plays an essential role in promoting oxygen evolution reaction(OER),and can simultaneously act as the active site for hydrogen evolution reaction(HER).Compared with pure Ru oxide nanosheet assemblies(Ru ONAs),the“5%Pt‐containing”Ru ONAs(5%Pt‐Ru ONAs)achieve much enhanced OER activity in 0.5 and 0.05 mol/L H_(2)SO_(4),with much lower overpotentials of 227 and 234 mV at 10 mA cm^(‒2),respectively.Experimental and theoretical analyses reveal that the atomically dispersed Pt incorporating into RuO_(2)lattice is conducive to increasing the concentration of O vacancies,which effectively enhances the interaction with reaction intermediate and thus lowers the energy barrier for the formation of OOH*.Moreover,benefited from the presence of Pt,the formation of RuO_(2)is more achievable when proper annealing is applied.In addition to OER,due to the presence of active Pt,the HER performance of 5%Pt‐Ru ONAs can also be ensured,thereby realizing efficient acidic overall water splitting.Finally,the excellent activity can also be achieved without sacrificing stability.This work highlights an attractive strategy for designing active and stable RuO_(2)‐based electrocatalysts for acidic overall water splitting.展开更多
High-entropy alloy nanoparticles(HEA-NPs)are highly underutilized in heterogeneous catalysis due to the absence of a reliable,sustainable,and facile synthetic method.Herein,we report a facile synthesis of HEA nanocata...High-entropy alloy nanoparticles(HEA-NPs)are highly underutilized in heterogeneous catalysis due to the absence of a reliable,sustainable,and facile synthetic method.Herein,we report a facile synthesis of HEA nanocatalysts realized via an ultrasounddriven wet chemistry method promoted by alcoholic ionic liquids(AILs).Owing to the intrinsic reducing ability of the hydroxyl group,AILs were synthesized and utilized as environmentally friendly alternatives to conventional reducing agents and volatile organic solvents in the synthetic process.Under high-intensity ultrasound irradiation,Au^(3+),Pd^(2+),Pt^(2+),Rh^(3+),and Ru^(3+)ions were coreduced and transformed into single-phase HEA(AuPdPtRhRu)nanocrystals without calcination.Characterization results reveal that the as-synthesized nanocrystals are composed of elements of Au,Pd,Pt,Rh,and Ru as expected.Compared to the monometallic counterparts such as Pd-NPs,the carbon-supported HEA nanocatalysts show superior catalytic performance for selective hydrogenation of phenol to cyclohexanone in terms of yield and selectivity.Our synthetic strategy provides an improved and facile methodology for the sustainable synthesis of multicomponent alloys for catalysis and other applications.展开更多
Exploration of structure-property relationships as a function of dopant concentration is commonly based on mean field theories for solid solutions.However,such theories that work well for semiconductors tend to fail i...Exploration of structure-property relationships as a function of dopant concentration is commonly based on mean field theories for solid solutions.However,such theories that work well for semiconductors tend to fail in materials with strong correlations,either in electronic behavior or chemical segregation.In these cases,the details of atomic arrangements are generally not explored and analyzed.The knowledge of the generative physics and chemistry of the material can obviate this problem,since defect configuration libraries as stochastic representation of atomic level structures can be generated,or parameters of mesoscopic thermodynamic models can be derived.To obtain such information for improved predictions,we use data from atomically resolved microscopic images that visualize complex structural correlations within the system and translate them into statistical mechanical models of structure formation.Given the significant uncertainties about the microscopic aspects of the material’s processing history along with the limited number of available images,we combine model optimization techniques with the principles of statistical hypothesis testing.We demonstrate the approach on data from a series of atomically-resolved scanning transmission electron microscopy images of Mo_(x)Re_(1-x)S_(2) at varying ratios of Mo/Re stoichiometries,for which we propose an effective interaction model that is then used to generate atomic configurations and make testable predictions at a range of concentrations and formation temperatures.展开更多
文摘A mechanochemical redox reaction between KMnO4 and CoCl2 was developed to obtain a CoxMn1-xOy catalyst with a specific surface area of 479 m^2 g^-1,which was higher than that obtained using a co-precipitation(CP)method(34 m2 g^-1),sol-gel(SG)method(72 m^2 g^-1),or solution redox process(131 m^2 g^-1).During catalytic combustion,this CoxMn1-xOy catalyst exhibited better activity(T100 for propylene=~200℃)than the control catalysts obtained using the SG(325℃)or CP(450℃)methods.The mechanical action,mainly in the form of kinetic energy and frictional heating,may generate a high degree of interstitial porosity,while the redox reaction could contribute to good dispersion of cobalt and manganese species.Moreover,the as-prepared CoxMn1-xOy catalyst worked well in the presence of water vapor(H2O 4.2%,>60 h)or SO2(100 ppm)and at high temperature(400℃,>60 h).The structure MnO2·(CoOOH)2.93 was suggested for the current CoxMn1-xOy catalyst.This catalyst could be extended to the total oxidation of other typical hydrocarbons(T90=150°C for ethanol,T90=225°C for acetone,T90=250℃for toluene,T90=120℃for CO,and T90=540℃for CH4).Scale-up of the synthesis of CoxMn1-xOy catalyst(1 kg)can be achieved via ball milling,which may provide a potential strategy for real world catalysis.
基金Y.C.and J.C.are contributed equally to the paper.Project supported by the National Natural Science Foundation of China (U19A2017)the Fundamental Research Funds for the Central South University and the Australian Research Council (DP180100731 and DP180100568)。
文摘The electrochemical carbon dioxide reduction reaction(CO_(2)RR),which can produce value-added chemical feedstocks,is a proton-coupled-electron process with sluggish kinetics.Thus,highly efficient,cheap catalysts are urgently required.Transition metal oxides such as CoO_(x),FeO_(x),and NiO_(x)are low-cost,low toxicity,and abundant materials for a wide range of electrochemical reactions,but are almost inert for CO_(2)RR.Here,we report for the first time that nitrogen doped carbon nanotubes(N-CNT)have a surprising activation effect on the activity and selectivity of transition metal-oxide(MO_(x)where M=Fe,Ni,and Co)nanoclusters for CO_(2)RR.MO_(x)supported on N-CNT,MO_(x)/N-CNT,achieves a CO yield of 2.6–2.8 mmol cm−2 min−1 at an overpotential of−0.55 V,which is two orders of magnitude higher than MO_(x)supported on acid treated CNTs(MO_(x)/O-CNT)and four times higher than pristine N-CNT.The faraday efficiency for electrochemical CO_(2)-to-CO conversion is as high as 90.3%at overpotential of 0.44 V.Both in-situ XAS measurements and DFT calculations disclose that MO_(x)nanoclusters can be hydrated in CO_(2)saturated KHCO_(3),and the N defects of N-CNT effectively stabilize these metal hydroxyl species under carbon dioxide reduction reaction conditions,which can split the water molecules and provide local protons to inhibit the poisoning of active sites under carbon dioxide reduction reaction conditions.
基金partially financially supported by NSF CBET-2033343.J.Z.thanks the support from National Natural Science Foundation of China(52172293,51772072,and 51672065)the Fundamental Research Funds for the Central Universities(JZ2021HGQB0282 and PA2021GDSK0088)+3 种基金financial support from the Key R&D Projects of Anhui Province(202104b11020016)the 111 Project(B18018)the National Synchrotron Light Source II,a U.S.Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No.DE-SC0012704the use of facilities within the Eyring Materials Center at Arizona State University supported in part by NNCI-ECCS-1542160.
文摘Regulating the selectivity toward a target hydrocarbon product is still the focus of CO_(2)electroreduction.Here,we discover that the original surface Cu species in Cu gas-diffusion electrodes plays a more important role than the surface roughness,local pH,and facet in governing the selectivity toward C_(1)or C_(2)hydrocarbons.The selectivity toward C_(2)H_(4) progressively increases,while CH_(4) decreases steadily upon lowering the Cu oxidation species fraction.At a relatively low electrodeposition voltage of 1.5 V,the Cu gas-diffusion electrode with the highest Cu^(δ+)/Cu^(0)ratio favors the pathways of∗CO hydrogenation to form CH_(4) with maximum Faradaic efficiency of 65.4%and partial current density of 228 mA cm^(−2)at−0.83 V vs RHE.At 2.0 V,the Cu gas-diffusion electrode with the lowest Cu^(δ+)/Cu^(0)ratio prefers C-C coupling to form C_(2)+products with Faradaic efficiency topping 80.1%at−0.75 V vs RHE,where the Faradaic efficiency of C_(2)H_(4) accounts for 46.4%and the partial current density of C_(2)H_(4) achieves 279 mA cm^(−2).This work demonstrates that the selectivity from CH_(4) to C_(2)H_(4) is switchable by tuning surface Cu species composition of Cu gas-diffusion electrodes.
基金This research is supported by the Science and Technology Program of Gansu Province(No.23JRRA880).
文摘With the current integration of distributed energy resources into the grid,the structure of distribution networks is becoming more complex.This complexity significantly expands the solution space in the optimization process for network reconstruction using intelligent algorithms.Consequently,traditional intelligent algorithms frequently encounter insufficient search accuracy and become trapped in local optima.To tackle this issue,a more advanced particle swarm optimization algorithm is proposed.To address the varying emphases at different stages of the optimization process,a dynamic strategy is implemented to regulate the social and self-learning factors.The Metropolis criterion is introduced into the simulated annealing algorithm to occasionally accept suboptimal solutions,thereby mitigating premature convergence in the population optimization process.The inertia weight is adjusted using the logistic mapping technique to maintain a balance between the algorithm’s global and local search abilities.The incorporation of the Pareto principle involves the consideration of network losses and voltage deviations as objective functions.A fuzzy membership function is employed for selecting the results.Simulation analysis is carried out on the restructuring of the distribution network,using the IEEE-33 node system and the IEEE-69 node system as examples,in conjunction with the integration of distributed energy resources.The findings demonstrate that,in comparison to other intelligent optimization algorithms,the proposed enhanced algorithm demonstrates a shorter convergence time and effectively reduces active power losses within the network.Furthermore,it enhances the amplitude of node voltages,thereby improving the stability of distribution network operations and power supply quality.Additionally,the algorithm exhibits a high level of generality and applicability.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21773303,21872172,51472267,and 51421002)the Chinese Academy of Sciences(Grant Nos.ZDYZ2015-1,XDB30000000,and XDB07030100)
文摘Opto–electromechanical coupling at the nanoscale is an important topic in new scientific studies and technical applications. In this work, the optically manipulated electromechanical behaviors of individual cadmium sulfide(CdS) nanowires are investigated by a customer-built optical holder inside transmission electron microscope, wherein in situ electromechanical resonance took place in conjunction with photo excitation. It is found that the natural resonance frequency of the nanowire under illumination becomes considerably lower than that under darkness. This redshift effect is closely related to the wavelength of the applied light and the diameter of the nanowires. Density functional theory(DFT) calculation shows that the photoexcitation leads to the softening of CdS nanowires and thus the redshift of natural frequency, which is in agreement with the experimental results.
文摘The development of highly potential electrocatalysts for acidic water electrolysis is particularly desirable for many energy‐related processes.Herein,we demonstrated a versatile strategy to activate and stabilize RuO_(2)‐based electrocatalyst for acidic water splitting by a trace of Pt,where Pt plays an essential role in promoting oxygen evolution reaction(OER),and can simultaneously act as the active site for hydrogen evolution reaction(HER).Compared with pure Ru oxide nanosheet assemblies(Ru ONAs),the“5%Pt‐containing”Ru ONAs(5%Pt‐Ru ONAs)achieve much enhanced OER activity in 0.5 and 0.05 mol/L H_(2)SO_(4),with much lower overpotentials of 227 and 234 mV at 10 mA cm^(‒2),respectively.Experimental and theoretical analyses reveal that the atomically dispersed Pt incorporating into RuO_(2)lattice is conducive to increasing the concentration of O vacancies,which effectively enhances the interaction with reaction intermediate and thus lowers the energy barrier for the formation of OOH*.Moreover,benefited from the presence of Pt,the formation of RuO_(2)is more achievable when proper annealing is applied.In addition to OER,due to the presence of active Pt,the HER performance of 5%Pt‐Ru ONAs can also be ensured,thereby realizing efficient acidic overall water splitting.Finally,the excellent activity can also be achieved without sacrificing stability.This work highlights an attractive strategy for designing active and stable RuO_(2)‐based electrocatalysts for acidic overall water splitting.
基金supported by the Division of Chemical Sciences,Geosciences,and Biosciences,Office of Basic Energy Sciences,US Department of Energy.
文摘High-entropy alloy nanoparticles(HEA-NPs)are highly underutilized in heterogeneous catalysis due to the absence of a reliable,sustainable,and facile synthetic method.Herein,we report a facile synthesis of HEA nanocatalysts realized via an ultrasounddriven wet chemistry method promoted by alcoholic ionic liquids(AILs).Owing to the intrinsic reducing ability of the hydroxyl group,AILs were synthesized and utilized as environmentally friendly alternatives to conventional reducing agents and volatile organic solvents in the synthetic process.Under high-intensity ultrasound irradiation,Au^(3+),Pd^(2+),Pt^(2+),Rh^(3+),and Ru^(3+)ions were coreduced and transformed into single-phase HEA(AuPdPtRhRu)nanocrystals without calcination.Characterization results reveal that the as-synthesized nanocrystals are composed of elements of Au,Pd,Pt,Rh,and Ru as expected.Compared to the monometallic counterparts such as Pd-NPs,the carbon-supported HEA nanocatalysts show superior catalytic performance for selective hydrogenation of phenol to cyclohexanone in terms of yield and selectivity.Our synthetic strategy provides an improved and facile methodology for the sustainable synthesis of multicomponent alloys for catalysis and other applications.
文摘Exploration of structure-property relationships as a function of dopant concentration is commonly based on mean field theories for solid solutions.However,such theories that work well for semiconductors tend to fail in materials with strong correlations,either in electronic behavior or chemical segregation.In these cases,the details of atomic arrangements are generally not explored and analyzed.The knowledge of the generative physics and chemistry of the material can obviate this problem,since defect configuration libraries as stochastic representation of atomic level structures can be generated,or parameters of mesoscopic thermodynamic models can be derived.To obtain such information for improved predictions,we use data from atomically resolved microscopic images that visualize complex structural correlations within the system and translate them into statistical mechanical models of structure formation.Given the significant uncertainties about the microscopic aspects of the material’s processing history along with the limited number of available images,we combine model optimization techniques with the principles of statistical hypothesis testing.We demonstrate the approach on data from a series of atomically-resolved scanning transmission electron microscopy images of Mo_(x)Re_(1-x)S_(2) at varying ratios of Mo/Re stoichiometries,for which we propose an effective interaction model that is then used to generate atomic configurations and make testable predictions at a range of concentrations and formation temperatures.
