Cuprous oxide(Cu2O)is an attractive material for photoelectrochemical(PEC)hydrogen production or photovoltaic application,because of its appropriate band gap,low material cost and non-toxic.In this paper,Cu2O films we...Cuprous oxide(Cu2O)is an attractive material for photoelectrochemical(PEC)hydrogen production or photovoltaic application,because of its appropriate band gap,low material cost and non-toxic.In this paper,Cu2O films were obtained by comproportionation in acid cupric sulfate solutions with varying concentrations of potassium nitrate.Photoelectrochemical and electrochemical experiments,such as zero-bias photocurrent responses,voltammograms,and Mott-Schottky measurements,show that the Cu2O films grown in low(≤0.75 mol dm^–3)and high(≥1.00 mol dm^–3)nitrate ion concentrations presented n-type and p-type conductivity,respectively.Open circuit potential and polarization behavior were monitored to investigate the mechanism of modulating conductivity type.Nitrate ions consume protons in the plating solution during comproportionation with different concentrations of nitrate ions creating different pH at the Cu2O/solution interface.This gradient leads to the transformation of Cu2Ofilms conductivity changing from n-type to p-type with increasing the concentration of nitrate ions in the plating solution.This method could be used to fabricate homojunction electrode on metal substrate for PEC hydrogen production or photoelectric application.展开更多
Green hydrogen is identified as one of the prime clean energy carriers due to its high energy density and a zero emission of CO_(2).A possible solution for the transport of H_(2)in a safe and low-cost way is in the fo...Green hydrogen is identified as one of the prime clean energy carriers due to its high energy density and a zero emission of CO_(2).A possible solution for the transport of H_(2)in a safe and low-cost way is in the form of liquid organic hydrogen carriers(LOHCs).As an alternative to loading LOHC with H_(2)via a two-step procedure involving preliminary electrolytic production of H_(2)and subsequent chemical hydrogenation of the LOHC,we explore here the possibility of electrochemical hydrogen storage(EHS)via conversion of proton of a proton donor into a hydrogen atom involved in covalent bonds with the LOHC(R)via a protoncoupled electron transfer(PCET)reaction:2nH^(+)+2ne^(-)+Rox■n H_(2)^(0)Rred.We chose 9-fluorenone/fluorenol(Fnone/Fnol)conversion as such a model PCET reaction.The electrochemical activation of Fnone via two sequential electron transfers was monitored with in-situ and operando spectroscopies in absence and in presence of different alcohols as proton donors of different reactivity,which enabled us to both quantify and get the mechanistic insight on PCET.The possibility of hydrogen extraction from the loaded carrier molecule was illustrated by chemical activation.展开更多
The construction of all-carbon molecule frameworks remains challenging. Herein, we report a facile and efficient one-pot synthesis of a novel all-carbon stair containing dimerized pentalene core using inexpensive cycl...The construction of all-carbon molecule frameworks remains challenging. Herein, we report a facile and efficient one-pot synthesis of a novel all-carbon stair containing dimerized pentalene core using inexpensive cyclopropyl alkyne catalyzed by in situ generated Cu(I) from the comproportionation reaction of Cu(II) salt and Cu powder under mild reaction conditions. The reaction proceeds via sequential acetylenic coupling, followed by cyclization and [2 + 2] cycloaddition to directly produce pentalene dimer, which is difficult to access by other established methods. Different mechanistic paths were studied for the pentalene formation using density functional theory, suggesting that the reaction also proceeds through acetylenic coupling followed by cyclization and [2 + 2] cycloaddition. Based on the activation energy barriers, Path 1 has the rate-determining step of 38.63 kcal/mol, which is the most thermodynamically preferred one among the four paths.展开更多
Coupling electrochemistry with optical techniques gives indepth insights into the interfacial processes in action.In that context,fluorescence confocal laser scanning microscopy(F-CLSM)enables an electrode surface cha...Coupling electrochemistry with optical techniques gives indepth insights into the interfacial processes in action.In that context,fluorescence confocal laser scanning microscopy(F-CLSM)enables an electrode surface characterization with spatial resolution in the lateral plane(xy)as well as in the axial direction(z),perpendicular to the electrode surface.However,like most optical techniques,fluorescence microscopy has intrinsic limitations,notably in terms of resolution and sensitivity,which are investigated in this contribution by conducting F-CLSM experiments with two disk electrodes of different sizes:a large microelectrode(LME,Ø=250μm)and a much smaller so-called ultramicroelectrode(UME,Ø=18μm).We demonstrated that the diffusion layers of both microelectrodes can be imaged with sufficient resolution and sensitivity to be quantitatively compared with the simulated concentration profiles.This work highlights the intrinsic technical challenges associated with this kind of coupled experiments,and it discusses the conditions that should be fulfilled to obtain reliable results at the microscale.These results pave the way toward reaction layer imaging down to micrometric resolution and could help decipher complex electrochemical reactions possibly involving transient species.展开更多
基金financially supported by the National Natural Science Foundation of China (No. 51302216 and 21375102)the Excellent Young Academic Backbone Program of the Northwest University+1 种基金the Open Fund of the State Key Laboratory of Multiphase Flow in Power Engineering of Chinathe Scientific Research Program funded by Shaanxi Provincial Education Department (No. 17JS121)
文摘Cuprous oxide(Cu2O)is an attractive material for photoelectrochemical(PEC)hydrogen production or photovoltaic application,because of its appropriate band gap,low material cost and non-toxic.In this paper,Cu2O films were obtained by comproportionation in acid cupric sulfate solutions with varying concentrations of potassium nitrate.Photoelectrochemical and electrochemical experiments,such as zero-bias photocurrent responses,voltammograms,and Mott-Schottky measurements,show that the Cu2O films grown in low(≤0.75 mol dm^–3)and high(≥1.00 mol dm^–3)nitrate ion concentrations presented n-type and p-type conductivity,respectively.Open circuit potential and polarization behavior were monitored to investigate the mechanism of modulating conductivity type.Nitrate ions consume protons in the plating solution during comproportionation with different concentrations of nitrate ions creating different pH at the Cu2O/solution interface.This gradient leads to the transformation of Cu2Ofilms conductivity changing from n-type to p-type with increasing the concentration of nitrate ions in the plating solution.This method could be used to fabricate homojunction electrode on metal substrate for PEC hydrogen production or photoelectric application.
基金financially supported by the Swedish Research Council(grant 2016-05990)the Knut and Alice Wallenberg Foundation(H2O2 and Cellfion)the Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Link?ping University(Faculty Grant SFO-Mat-Li U No.200900971)。
文摘Green hydrogen is identified as one of the prime clean energy carriers due to its high energy density and a zero emission of CO_(2).A possible solution for the transport of H_(2)in a safe and low-cost way is in the form of liquid organic hydrogen carriers(LOHCs).As an alternative to loading LOHC with H_(2)via a two-step procedure involving preliminary electrolytic production of H_(2)and subsequent chemical hydrogenation of the LOHC,we explore here the possibility of electrochemical hydrogen storage(EHS)via conversion of proton of a proton donor into a hydrogen atom involved in covalent bonds with the LOHC(R)via a protoncoupled electron transfer(PCET)reaction:2nH^(+)+2ne^(-)+Rox■n H_(2)^(0)Rred.We chose 9-fluorenone/fluorenol(Fnone/Fnol)conversion as such a model PCET reaction.The electrochemical activation of Fnone via two sequential electron transfers was monitored with in-situ and operando spectroscopies in absence and in presence of different alcohols as proton donors of different reactivity,which enabled us to both quantify and get the mechanistic insight on PCET.The possibility of hydrogen extraction from the loaded carrier molecule was illustrated by chemical activation.
基金financially supported by the National Natural Science Foundation of China (Nos. 91961105, 21822107,21571115, 21827801)the Natural Science Foundation of Shandong Province (Nos. ZR2019ZD45, JQ201803 and ZR2017MB061)+2 种基金the Taishan Scholar Project of Shandong Province of China (Nos.tsqn201812003 and ts20190908)Project for Scientific Research Innovation Team of Young Scholar in Colleges and Universities of Shandong Province (No. 2019KJC028)Natural Science Foundation of Shandong Province (No. ZR2020ZD35)。
文摘The construction of all-carbon molecule frameworks remains challenging. Herein, we report a facile and efficient one-pot synthesis of a novel all-carbon stair containing dimerized pentalene core using inexpensive cyclopropyl alkyne catalyzed by in situ generated Cu(I) from the comproportionation reaction of Cu(II) salt and Cu powder under mild reaction conditions. The reaction proceeds via sequential acetylenic coupling, followed by cyclization and [2 + 2] cycloaddition to directly produce pentalene dimer, which is difficult to access by other established methods. Different mechanistic paths were studied for the pentalene formation using density functional theory, suggesting that the reaction also proceeds through acetylenic coupling followed by cyclization and [2 + 2] cycloaddition. Based on the activation energy barriers, Path 1 has the rate-determining step of 38.63 kcal/mol, which is the most thermodynamically preferred one among the four paths.
基金the CNRS for financial support through the MITI program(project EMERAUDE 2023-2024).
文摘Coupling electrochemistry with optical techniques gives indepth insights into the interfacial processes in action.In that context,fluorescence confocal laser scanning microscopy(F-CLSM)enables an electrode surface characterization with spatial resolution in the lateral plane(xy)as well as in the axial direction(z),perpendicular to the electrode surface.However,like most optical techniques,fluorescence microscopy has intrinsic limitations,notably in terms of resolution and sensitivity,which are investigated in this contribution by conducting F-CLSM experiments with two disk electrodes of different sizes:a large microelectrode(LME,Ø=250μm)and a much smaller so-called ultramicroelectrode(UME,Ø=18μm).We demonstrated that the diffusion layers of both microelectrodes can be imaged with sufficient resolution and sensitivity to be quantitatively compared with the simulated concentration profiles.This work highlights the intrinsic technical challenges associated with this kind of coupled experiments,and it discusses the conditions that should be fulfilled to obtain reliable results at the microscale.These results pave the way toward reaction layer imaging down to micrometric resolution and could help decipher complex electrochemical reactions possibly involving transient species.
