Currently,one of the critical issues in the world is finding an appropriate green alternative to fossil fuels due to the concerns about global warming.As a hydrogen source,formic acid has been given particular attenti...Currently,one of the critical issues in the world is finding an appropriate green alternative to fossil fuels due to the concerns about global warming.As a hydrogen source,formic acid has been given particular attention owing to the attractive features such as highenergy density,no toxicity,high stability at ambient temperature and high hydrogen content.Introducing an affordable and highly efficient catalyst with easy recovery from the reaction mixture for selective dehydrogenation of formic acid is still demanding.In this report,we used a simple onestep process to synthesize Ni@Pd core shell nanoparticles on 3aminopropyltriethoxysilane modified Fe3O4 nanoparticles.The existence of Ni and Pd results in a synergic effect on the catalytic activity.The—NH2 groups play an important role for obtaining welldispersed ultrafine particles with high surface area and active sites.In addition,Fe3O4 lead to convenient magnetic recovery of the catalyst from reaction mixture.Our results indicate that the asprepared catalyst give the superb turnover frequency of 5367.8 h 1 with no additive,which is higher than most of the previously reported catalysts.展开更多
The oxidations of D-fructose and D-lactose were monitored spectrophotometrically by potassium permanganate in acidic medium at λmax 545 nm. Reaction demonstrated that the two oxidative species of permanganate were in...The oxidations of D-fructose and D-lactose were monitored spectrophotometrically by potassium permanganate in acidic medium at λmax 545 nm. Reaction demonstrated that the two oxidative species of permanganate were involved in an acidic oxidation of the sugars. It was established that respective acids of sugars as well as arabinonic and formic acid were the oxidation products. Respective acids of sugars were the results of reactive oxygen species of permanganate ions in acidic conditions while arabinonic and formic acids due to the cleavage of C__C bond through MnO-4 species. It was first order kinetics with respect to [MnO-4 ], [fructose], [lactose] and [H+]. Hg was used to accelerate the slow oxidation of lactose. Effect of varying salt electrolyte concentration was insignificant showing that the molecular species was involved in the rate determining step. Formic and arabinonic acids and respective acids were analyzed through spot and spectroscopic studies respectively. Reaction was monitored at different temperatures and thermodynamics activation parameters were determined. A mechanism consistent with kinetic studies, spectral evidences, stoichiometry of the reactions and product analysis has been proposed for the oxidation of fructose and lactose in absence and presence of catalyst respectively.展开更多
Sn-based electrocatalysts have been gaining increasing attention due to their potential contribution in the conversion of CO2 into HCOOH driven by sustainable energy sources;however,their actual capability to catalyze...Sn-based electrocatalysts have been gaining increasing attention due to their potential contribution in the conversion of CO2 into HCOOH driven by sustainable energy sources;however,their actual capability to catalyze CO2 reduction reaction(CO2RR)still cannot meet the requirements of commercial-scale applications.Therefore developing Snbased catalyst is of vital importance.Herein,the sheet-like heterophase Sn O2/Sn3O4 with a high density of phase interfaces has been first engineered by a facile hydrothermal process,with Sn3O4 as the dominant phase.The evidences from experiments and theoretical simulation indicate that the charge redistribution and built-in electric field at heterophase interfaces boost CO2 adsorption and HCOO*formation,accelerate the charge transfer between the catalysts and reactants,and ultimately greatly elevate the intrinsic activity of the heterophase Sn O2/Sn3O4 towards CO2 RR.Meanwhile,the in-situ generated porous structure and metal Sn during CO2 RR improve the mass transmission within the interlayer volume and the conductivity of Sn O2/Sn3O4.The heterophase Sn O2/Sn3O4 displays high activity and selectivity for CO2 RR,achieving an improvement in CO2 reduction current density,88.3%Faradaic efficiency of HCOOH conversion at-0.9 VRHE,along with a long-term tolerance in CO2 RR.This study demonstrates that heterophase interface engineering is an efficient strategy to regulate advanced catalysts for different applications.展开更多
文摘Currently,one of the critical issues in the world is finding an appropriate green alternative to fossil fuels due to the concerns about global warming.As a hydrogen source,formic acid has been given particular attention owing to the attractive features such as highenergy density,no toxicity,high stability at ambient temperature and high hydrogen content.Introducing an affordable and highly efficient catalyst with easy recovery from the reaction mixture for selective dehydrogenation of formic acid is still demanding.In this report,we used a simple onestep process to synthesize Ni@Pd core shell nanoparticles on 3aminopropyltriethoxysilane modified Fe3O4 nanoparticles.The existence of Ni and Pd results in a synergic effect on the catalytic activity.The—NH2 groups play an important role for obtaining welldispersed ultrafine particles with high surface area and active sites.In addition,Fe3O4 lead to convenient magnetic recovery of the catalyst from reaction mixture.Our results indicate that the asprepared catalyst give the superb turnover frequency of 5367.8 h 1 with no additive,which is higher than most of the previously reported catalysts.
文摘The oxidations of D-fructose and D-lactose were monitored spectrophotometrically by potassium permanganate in acidic medium at λmax 545 nm. Reaction demonstrated that the two oxidative species of permanganate were involved in an acidic oxidation of the sugars. It was established that respective acids of sugars as well as arabinonic and formic acid were the oxidation products. Respective acids of sugars were the results of reactive oxygen species of permanganate ions in acidic conditions while arabinonic and formic acids due to the cleavage of C__C bond through MnO-4 species. It was first order kinetics with respect to [MnO-4 ], [fructose], [lactose] and [H+]. Hg was used to accelerate the slow oxidation of lactose. Effect of varying salt electrolyte concentration was insignificant showing that the molecular species was involved in the rate determining step. Formic and arabinonic acids and respective acids were analyzed through spot and spectroscopic studies respectively. Reaction was monitored at different temperatures and thermodynamics activation parameters were determined. A mechanism consistent with kinetic studies, spectral evidences, stoichiometry of the reactions and product analysis has been proposed for the oxidation of fructose and lactose in absence and presence of catalyst respectively.
基金the National Natural Science Foundation of China(21573062,21631004 and 21901065)the Natural Science Foundation of Heilongjiang Province(B2018008)+1 种基金the Youth Science and Technology Innovation Team Project of Heilongjiang Province(2018-KYYWF-1593)the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(UNPYSCT-2018009)。
文摘Sn-based electrocatalysts have been gaining increasing attention due to their potential contribution in the conversion of CO2 into HCOOH driven by sustainable energy sources;however,their actual capability to catalyze CO2 reduction reaction(CO2RR)still cannot meet the requirements of commercial-scale applications.Therefore developing Snbased catalyst is of vital importance.Herein,the sheet-like heterophase Sn O2/Sn3O4 with a high density of phase interfaces has been first engineered by a facile hydrothermal process,with Sn3O4 as the dominant phase.The evidences from experiments and theoretical simulation indicate that the charge redistribution and built-in electric field at heterophase interfaces boost CO2 adsorption and HCOO*formation,accelerate the charge transfer between the catalysts and reactants,and ultimately greatly elevate the intrinsic activity of the heterophase Sn O2/Sn3O4 towards CO2 RR.Meanwhile,the in-situ generated porous structure and metal Sn during CO2 RR improve the mass transmission within the interlayer volume and the conductivity of Sn O2/Sn3O4.The heterophase Sn O2/Sn3O4 displays high activity and selectivity for CO2 RR,achieving an improvement in CO2 reduction current density,88.3%Faradaic efficiency of HCOOH conversion at-0.9 VRHE,along with a long-term tolerance in CO2 RR.This study demonstrates that heterophase interface engineering is an efficient strategy to regulate advanced catalysts for different applications.
