Active-phase engineering is regularly utilized to tune the selectivity of metal nanoparticles （NPs） in heterogeneous catalysis. However, the lack of understanding of the active phase in electrocatalysis has hampered...Active-phase engineering is regularly utilized to tune the selectivity of metal nanoparticles （NPs） in heterogeneous catalysis. However, the lack of understanding of the active phase in electrocatalysis has hampered the development of efficient catalysts for CO2 electroreduction. Herein, we report the systematic engineering of active phases of Pd NPs, which are exploited to select reaction pathways for CO2 electroreduction. In situ X-ray absorption spectroscopy, in situ attenuated total reflection-infrared spectroscopy, and density functional theory calculations suggest that the formation of a hydrogen-adsorbed Pd surface on a mixture of the α- and β-phases of a palladium-hydride core （α＋β PdHx@PdHx） above -0.2 V （vs. a reversible hydrogen electrode） facilitates formate production via the HCOO intermediate, whereas the formation of a metallic Pd surface on the β-phase Pd hydride core （β PdHx@Pd） below -0.5 V promotes CO production via the COOH＂ intermediate. The main product, which is either formate or CO, can be selectively produced with high Faradaic efficiencies （〉90%） and mass activities in the potential window of 0.05 to -0.9 V with scalable application demonstration.展开更多
Direct electrochemical reduction of mixed TiO2 and NiO powders to TiNi alloy has been successfully demonstrated in molten CaCl2 at 900℃ by constant voltage electrolysis. The electrolysis en- ergy consumption was as l...Direct electrochemical reduction of mixed TiO2 and NiO powders to TiNi alloy has been successfully demonstrated in molten CaCl2 at 900℃ by constant voltage electrolysis. The electrolysis en- ergy consumption was as low as 23.4 kWh/kg-TiNi, although the current efficiency was 20.5% in the pre- liminary experiments. During the process, NiO was first reduced to Ni at high speed, accompanied by TiO2 being perovskitized to CaTiO3?x which was gradually reduced to Ni3Ti and TiNi, assisted by the depolarization of the preformed Ni. The cell voltage for preparation of the TiNi alloy was lower than that for Ti. Adjusting the cell voltage not only affected the reduction speed, but also offered a convenient ac- cess to the preparation of the nickel/perovskite composite.展开更多
The electrochemical reduction of coumarin at GC electrode in 1-n-butyl-3-methylimidazolium tetrafluoroborate(BMIMBF4) room temperature ionic liquid is reported.Coumarin exhibits a one-electron,irreversible reduction t...The electrochemical reduction of coumarin at GC electrode in 1-n-butyl-3-methylimidazolium tetrafluoroborate(BMIMBF4) room temperature ionic liquid is reported.Coumarin exhibits a one-electron,irreversible reduction to caroanion radical,and the latter species undergoes fast dimerization to dihydrodimer.The influences of scan rate, concentration and temperature were studied by cyclic voltammetry.The results show that the reaction is diffusion controlled.The diffusion coefficient D of coumarin in BMIMBF4 from Chronocoulometry is 5.066×10-7 cm2/s. Furthermore,the influences of water and substituting group during the electroreduction are discussed. These preliminary electrochemical experiments show encouraging results for the use of ionic liquids in a 'green' electrochemistry.展开更多
Uncovering the structure evolution and real active species of energy catalytic materials under reaction conditions is important for both understanding structure-activity relationship and constructing electrocatalysts ...Uncovering the structure evolution and real active species of energy catalytic materials under reaction conditions is important for both understanding structure-activity relationship and constructing electrocatalysts for CO2 electroreduction(CO2ER).And integrating CO2ER with an anodic organic transformation to replace the oxygen evolution reaction is highly desirable.Here,In2O3 is selected as the model material to reveal the surface reconstruction under CO2ER condition.In situ and ex situ results reveal that the electrochemical in situ reconstruction of crystalline In2O3 leads to the formation of crystalline-In/amorphous In2O3-x heterostructure(In/In2O3-x).In/In2O3-xacts as the real active phase with Faradaic efficiency of^89.2%for the formate,outperforming In(~67.5%).The improved performance can be ascribed to electron-rich In rectified by Schottky effect of In2O3-xheterostructure.Impressively,formate and high-value octanenitrile can be simultaneously achieved by integrating CO2ER with octylamine oxidation in an In2O3-x||Ni2P two-electrode electrolyzer.展开更多
Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced nickel-nitrogen-carbon single-site catalys...Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced nickel-nitrogen-carbon single-site catalyst is conveniently prepared by pyrolyzing the mixture of NiCl2 and phenanthroline, which exhibits a Faradaic efficiency plateau of > 87% in a wide potential window of −0.6 – −1.0 V. Further S-doping by adding KSCN into the precursor much enhances the CO specific current density by 68%, up to 37.5 A·g−1 at −0.8 V, along with an improved CO Faradaic efficiency plateau of > 90%. Such an enhancement can be ascribed to the facilitated CO pathway and suppressed hydrogen evolution from thermodynamic viewpoint as well as the increased electroactive surface area and improved charge transfer fromkinetic viewpoint due to the S-doping. This study demonstrates a simple and effective approach to advanced electrocatalysts by synergetic modification of the porous carbon-based support and electronic structure of the active sites.展开更多
Electroreduction of Ni(Ⅱ) to metallic Ni in urea NaBr melt at 373 K is irreversible in one step. Gd(Ⅲ) is not reduced to Gd alone, but can be inductively codeposited with Ni(Ⅱ). The amorphous Gd Ni alloy films were...Electroreduction of Ni(Ⅱ) to metallic Ni in urea NaBr melt at 373 K is irreversible in one step. Gd(Ⅲ) is not reduced to Gd alone, but can be inductively codeposited with Ni(Ⅱ). The amorphous Gd Ni alloy films were obtained by potentiostatic electrolysis and galvanostatic electrolysis. With the cathode potential shift to negative direction and the increase of current density, the content of gadolinium in the alloy increases first, and then drops down gradually. The molar ratio of Gd(Ⅲ) to Ni(Ⅱ) and the time also influence the content of Gd. Crystalline GdNi 3 alloy was obtained after heat treatment of the deposit. [展开更多
A novel technology which combined electrochemical process catalyzed by manganese mineral with electro-assisted coagulation process was proposed in this study. The mineralization of organic pollutant from simulated dye...A novel technology which combined electrochemical process catalyzed by manganese mineral with electro-assisted coagulation process was proposed in this study. The mineralization of organic pollutant from simulated dye wastewater containing an azo dye Acid Red B（ARB） was experimentally investigated using this method. It was found that the manganese mineral could catalyze the electrochemical process dramatically. The TOC removal percentage of electrochemical treatment catalyzed by manganese mineral was 43.6% while the TOC removal percentage of the process using the manganese mineral alone and using the electrolysis alone were 9.3% and 20.8%, respectively. Moreover, it was found that combined electroxidation with electro-assisted coagulation process could more effectively eliminate ARB. After a period of 180 min electrooxidation and 300 min electroreduction, almost 66.9% of TOC was removed, and the dissolved Mn^2＋. could be effectivly removed. The effects of the order of oxidation and reduction, the proper ratio electrooxidation/reduction time, and current density on the removal efficiency were investigated in detail. In addition, a proposed mechanism of manganese-mineral-catalyzed electrooxidation-reduction process was discussed in this paper.展开更多
文摘Active-phase engineering is regularly utilized to tune the selectivity of metal nanoparticles （NPs） in heterogeneous catalysis. However, the lack of understanding of the active phase in electrocatalysis has hampered the development of efficient catalysts for CO2 electroreduction. Herein, we report the systematic engineering of active phases of Pd NPs, which are exploited to select reaction pathways for CO2 electroreduction. In situ X-ray absorption spectroscopy, in situ attenuated total reflection-infrared spectroscopy, and density functional theory calculations suggest that the formation of a hydrogen-adsorbed Pd surface on a mixture of the α- and β-phases of a palladium-hydride core （α＋β PdHx@PdHx） above -0.2 V （vs. a reversible hydrogen electrode） facilitates formate production via the HCOO intermediate, whereas the formation of a metallic Pd surface on the β-phase Pd hydride core （β PdHx@Pd） below -0.5 V promotes CO production via the COOH＂ intermediate. The main product, which is either formate or CO, can be selectively produced with high Faradaic efficiencies （〉90%） and mass activities in the potential window of 0.05 to -0.9 V with scalable application demonstration.
基金the National Natural Science Foundation of China （Grant Nos 20125308 and 20573081）.
文摘Direct electrochemical reduction of mixed TiO2 and NiO powders to TiNi alloy has been successfully demonstrated in molten CaCl2 at 900℃ by constant voltage electrolysis. The electrolysis en- ergy consumption was as low as 23.4 kWh/kg-TiNi, although the current efficiency was 20.5% in the pre- liminary experiments. During the process, NiO was first reduced to Ni at high speed, accompanied by TiO2 being perovskitized to CaTiO3?x which was gradually reduced to Ni3Ti and TiNi, assisted by the depolarization of the preformed Ni. The cell voltage for preparation of the TiNi alloy was lower than that for Ti. Adjusting the cell voltage not only affected the reduction speed, but also offered a convenient ac- cess to the preparation of the nickel/perovskite composite.
文摘The electrochemical reduction of coumarin at GC electrode in 1-n-butyl-3-methylimidazolium tetrafluoroborate(BMIMBF4) room temperature ionic liquid is reported.Coumarin exhibits a one-electron,irreversible reduction to caroanion radical,and the latter species undergoes fast dimerization to dihydrodimer.The influences of scan rate, concentration and temperature were studied by cyclic voltammetry.The results show that the reaction is diffusion controlled.The diffusion coefficient D of coumarin in BMIMBF4 from Chronocoulometry is 5.066×10-7 cm2/s. Furthermore,the influences of water and substituting group during the electroreduction are discussed. These preliminary electrochemical experiments show encouraging results for the use of ionic liquids in a 'green' electrochemistry.
基金the National Natural Science Foundation of China (21871206 and 21701122)。
文摘Uncovering the structure evolution and real active species of energy catalytic materials under reaction conditions is important for both understanding structure-activity relationship and constructing electrocatalysts for CO2 electroreduction(CO2ER).And integrating CO2ER with an anodic organic transformation to replace the oxygen evolution reaction is highly desirable.Here,In2O3 is selected as the model material to reveal the surface reconstruction under CO2ER condition.In situ and ex situ results reveal that the electrochemical in situ reconstruction of crystalline In2O3 leads to the formation of crystalline-In/amorphous In2O3-x heterostructure(In/In2O3-x).In/In2O3-xacts as the real active phase with Faradaic efficiency of^89.2%for the formate,outperforming In(~67.5%).The improved performance can be ascribed to electron-rich In rectified by Schottky effect of In2O3-xheterostructure.Impressively,formate and high-value octanenitrile can be simultaneously achieved by integrating CO2ER with octylamine oxidation in an In2O3-x||Ni2P two-electrode electrolyzer.
基金supported by the National Natural Science Foundation of China(20973048)Key Laboratory of Superlight Material and Surface Technology of Ministry of Education of China+1 种基金Heilongjiang Postdoc Foundation,China(LBH-Q06091)Fund of Harbin Engineering University,China(HEUFT07030,HEUFT07051)~~
基金the National Key Research and Development Program of China(Nos.2017 YFA0206500 and 2018YFA0209103)the National Natural Science Foundation of China(Nos.21832003,21773111,21972061,51571110,and 21573107).The numerical calculations have been done on the computing facilities in the High Performance Computing Center(HPCC)of Nanjing University.
文摘Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced nickel-nitrogen-carbon single-site catalyst is conveniently prepared by pyrolyzing the mixture of NiCl2 and phenanthroline, which exhibits a Faradaic efficiency plateau of > 87% in a wide potential window of −0.6 – −1.0 V. Further S-doping by adding KSCN into the precursor much enhances the CO specific current density by 68%, up to 37.5 A·g−1 at −0.8 V, along with an improved CO Faradaic efficiency plateau of > 90%. Such an enhancement can be ascribed to the facilitated CO pathway and suppressed hydrogen evolution from thermodynamic viewpoint as well as the increased electroactive surface area and improved charge transfer fromkinetic viewpoint due to the S-doping. This study demonstrates a simple and effective approach to advanced electrocatalysts by synergetic modification of the porous carbon-based support and electronic structure of the active sites.
文摘Electroreduction of Ni(Ⅱ) to metallic Ni in urea NaBr melt at 373 K is irreversible in one step. Gd(Ⅲ) is not reduced to Gd alone, but can be inductively codeposited with Ni(Ⅱ). The amorphous Gd Ni alloy films were obtained by potentiostatic electrolysis and galvanostatic electrolysis. With the cathode potential shift to negative direction and the increase of current density, the content of gadolinium in the alloy increases first, and then drops down gradually. The molar ratio of Gd(Ⅲ) to Ni(Ⅱ) and the time also influence the content of Gd. Crystalline GdNi 3 alloy was obtained after heat treatment of the deposit. [
文摘A novel technology which combined electrochemical process catalyzed by manganese mineral with electro-assisted coagulation process was proposed in this study. The mineralization of organic pollutant from simulated dye wastewater containing an azo dye Acid Red B（ARB） was experimentally investigated using this method. It was found that the manganese mineral could catalyze the electrochemical process dramatically. The TOC removal percentage of electrochemical treatment catalyzed by manganese mineral was 43.6% while the TOC removal percentage of the process using the manganese mineral alone and using the electrolysis alone were 9.3% and 20.8%, respectively. Moreover, it was found that combined electroxidation with electro-assisted coagulation process could more effectively eliminate ARB. After a period of 180 min electrooxidation and 300 min electroreduction, almost 66.9% of TOC was removed, and the dissolved Mn^2＋. could be effectivly removed. The effects of the order of oxidation and reduction, the proper ratio electrooxidation/reduction time, and current density on the removal efficiency were investigated in detail. In addition, a proposed mechanism of manganese-mineral-catalyzed electrooxidation-reduction process was discussed in this paper.
