With the continuous improvement of solar energy production capacity,how to effectively use the electricity generated by renewable solar energy for electrochemical conversion of biomass is a hot topic.Electrochemical c...With the continuous improvement of solar energy production capacity,how to effectively use the electricity generated by renewable solar energy for electrochemical conversion of biomass is a hot topic.Electrochemical conversion of 5-hydroxymethylfurfural(HMF)to biofuels and value-added oxygenated commodity chemicals provides a promising and alternative pathway to convert re-newable electricity into chemicals.Although nickel-based eletrocatalysts are well-known for HMF oxidation,their relatively low intrinsic activity,poor conductivity and stability still limit the poten-tial applications.Here,we report the fabrication of a freestanding nickel-based electrode,in which Ni(OH)_(2) species were in-situ constructed on Ni foam(NF)support using a facile ac-id-corrosion-induced strategy.The Ni(OH)2/NF electrocatalyst exhibits stable and efficient electro-chemical HMF oxidation into 2,5-furandicarboxylic acid(FDCA)with HMF conversion close to 100% with high Faraday efficiency.In-situ formation strategy results in a compact interface between Ni(OH)_(2) and NF,which contributes to good conductivity and stability during electrochemical reac-tions.The superior performance benefits from dynamic cyclic evolution of Ni(OH)_(2) to NiOOH,which acts as the reactive species for HMF oxidation to FDCA.A scaled-up device based on a continu-ous-flow electrolytic cell was also established,giving stable operation with a high FDCA production rate of 27 mg h^(-1)cm^(−2).This job offers a straightforward,economical,and scalable design strategy to design efficient and durable catalysts for electrochemical conversion of valuable chemicals.展开更多
Formaldehyde（HCHO）is carcinogenic and teratogenic,and is therefore a serious danger to human health.It also adversely affects air quality.Catalytic oxidation is an efficient technique for removing HCHO.The developme...Formaldehyde（HCHO）is carcinogenic and teratogenic,and is therefore a serious danger to human health.It also adversely affects air quality.Catalytic oxidation is an efficient technique for removing HCHO.The development of highly efficient and stable catalysts that can completely convert HCHO at low temperatures,even room temperature,is important.Supported Pt and Pd catalysts can completely convert HCHO at room temperature,but their industrial applications are limited because they are expensive.The catalytic activities in HCHO oxidation of transition-metal oxide catalysts such as manganese and cobalt oxides with unusual morphologies are better than those of traditional MnO2,Co3O4,or other metal oxides.This is attributed to their specific structures,high specific surface areas,and other factors such as active phase,reducibility,and amount of surface active oxygens.Such catalysts with various morphologies have great potential and can also be used as catalyst supports.The loading of relatively cheap Ag or Au on transition-metal oxides with special morphologies potentially improves the catalytic activity in HCHO removal at room temperature.The preparation and development of new nanocatalysts with various morphologies and structures is important for HCHO removal.In this paper,research progress on precious-metal and transition-metal oxide catalyst systems for HCHO oxidation is reviewed; topics such as oxidation properties,structure–activity relationships,and factors influencing the catalytic activity and reaction mechanism are discussed.Future prospects and directions for the development of such catalysts are also covered.展开更多
The selective oxidation of toluene and its derivatives is extremely important in the chemical industry.The use of photocatalysis in organic synthesis has attracted considerable attention among synthetic chemists becau...The selective oxidation of toluene and its derivatives is extremely important in the chemical industry.The use of photocatalysis in organic synthesis has attracted considerable attention among synthetic chemists because of its ＂green＂ environmental characteristics.In this study,nanoscale Bi_2WO_6with a flower-like morphology was found to be a highly efficient photocatalyst in the catalytic oxidation of toluene and its derivatives using O_2 as the oxidant.The loading of Pd nanoparticles as a cocatalyst onto the flower-like Bi_2WO_6 was found to produce a significant enhancement in the catalytic activity.Mechanistic investigation showed that the superior performance of Pd/Bi_2WO_6 could be attributed to the improvement of both the reductive and oxidative abilities of Bi_2WO_6 by the loading of the cocatalyst.展开更多
Gold stabilized on reducible oxide （CeO2 and FeOx） and irreducible oxide （γ‐Al2O3, SiO2, and HZSM‐5） were prepared by deposition precipitation method and tested for catalytic oxidation of formaldehyde （HCHO） ...Gold stabilized on reducible oxide （CeO2 and FeOx） and irreducible oxide （γ‐Al2O3, SiO2, and HZSM‐5） were prepared by deposition precipitation method and tested for catalytic oxidation of formaldehyde （HCHO） at room temperature under high GHSV of 600000 ml/（g＆#183;s）. Au/γ‐Al2O3 cata‐lyst showed distinctive catalytic performance, presenting the highest initial HCHO conversion and stability. Correlating the reaction rate with Au particle size, there is a linear relationship, suggesting that the smaller Au particle size with higher dispersion possesses high reactivity for HCHO oxida‐tion. All the catalysts deactivated at high GHSV （600000 ml/（g＆#183;s））, but in a quite different rate. Re‐ducible oxide （CeO2 and FeOx） could stabilize gold through O linkage and therefore exhibits a better stability for HCHO oxidation reaction. However, the aggregation of gold particles occurred over Au/SiO2 and Au/HZSM‐5 catalysts, which result in the fast deactivation. Therefore, our results sug‐gest that the reducibility of the supports for Au catalysis has no direct influence on the activity, but affects the catalytic stability.展开更多
Formaldehyde(HCHO) is a common indoor pollutant, long-term exposure to HCHO may harm human health. Its efficient removal at mild conditions is still challenging. The catalytic oxidation of HCHO molecules on a single a...Formaldehyde(HCHO) is a common indoor pollutant, long-term exposure to HCHO may harm human health. Its efficient removal at mild conditions is still challenging. The catalytic oxidation of HCHO molecules on a single atomic catalyst, Ti-decorated Ti3C2O2(Ti/Ti3C2O2) monolayer, is investigated by performing the first principles calculations in this work. It demonstrates that Ti atoms can be easily well dispersed at the form of single atom on Ti3C2O2 monolayer without aggregation. For HCHO catalytic oxidation, both Langmuir-Hinshelwood(LH) and Eley-Rideal(ER) mechanisms are considered. The results show that the step of HCHO dissociative adsorption on Ti/Ti3C2O2 with activated O2 can release high energy of 4.05 e V based on the ER mechanism, which can help to overcome the energy barrier(1.04 e V) of the subsequent reaction steps. The charge transfer from *OH group to CO molecule(dissociated from HCHO) not only promotes *OH group activation but also plays an important role in the H2 O generation along the ER mechanism. Therefore, HCHO can be oxidized easily on Ti/Ti3C2O2 monolayer, this work could provide significant guidance to develop effective non-noble metal catalysts for HCHO oxidation and broaden the applications of MXene-based materials.展开更多
Rubidium phosphate can be more conveniently obtained by extracting trace Rb+ from the salt lake brine. Rb_3PO_4 was found to be an excellent heterogeneous catalyst for transfer hydrogenation. Rb_3PO_4 lost 70% of its ...Rubidium phosphate can be more conveniently obtained by extracting trace Rb+ from the salt lake brine. Rb_3PO_4 was found to be an excellent heterogeneous catalyst for transfer hydrogenation. Rb_3PO_4 lost 70% of its active sites after adsorbing water, but the remaining was not affected. The reductions of aldehydes and ketones, when promoted by Rb_3PO_4, were allowed at room temperature. The activities of substrates at room temperature followed a descending order of 2,6-dichlorobenzaldehyde> 4-bromobenzaldehyde>benzaldehyde>acetophenone>anisaldehyde>butanone. A new catalytic cycle postulating a six-membered cyclic transition state for the reductions of aldehydes and ketones was proposed. These results exploited the catalytic usage of Rb_3PO_4 and worth in industrial application.展开更多
文摘With the continuous improvement of solar energy production capacity,how to effectively use the electricity generated by renewable solar energy for electrochemical conversion of biomass is a hot topic.Electrochemical conversion of 5-hydroxymethylfurfural(HMF)to biofuels and value-added oxygenated commodity chemicals provides a promising and alternative pathway to convert re-newable electricity into chemicals.Although nickel-based eletrocatalysts are well-known for HMF oxidation,their relatively low intrinsic activity,poor conductivity and stability still limit the poten-tial applications.Here,we report the fabrication of a freestanding nickel-based electrode,in which Ni(OH)_(2) species were in-situ constructed on Ni foam(NF)support using a facile ac-id-corrosion-induced strategy.The Ni(OH)2/NF electrocatalyst exhibits stable and efficient electro-chemical HMF oxidation into 2,5-furandicarboxylic acid(FDCA)with HMF conversion close to 100% with high Faraday efficiency.In-situ formation strategy results in a compact interface between Ni(OH)_(2) and NF,which contributes to good conductivity and stability during electrochemical reac-tions.The superior performance benefits from dynamic cyclic evolution of Ni(OH)_(2) to NiOOH,which acts as the reactive species for HMF oxidation to FDCA.A scaled-up device based on a continu-ous-flow electrolytic cell was also established,giving stable operation with a high FDCA production rate of 27 mg h^(-1)cm^(−2).This job offers a straightforward,economical,and scalable design strategy to design efficient and durable catalysts for electrochemical conversion of valuable chemicals.
基金supported by the National Natural Science Foundation of China(21325731,51478241,21221004)~~
文摘Formaldehyde（HCHO）is carcinogenic and teratogenic,and is therefore a serious danger to human health.It also adversely affects air quality.Catalytic oxidation is an efficient technique for removing HCHO.The development of highly efficient and stable catalysts that can completely convert HCHO at low temperatures,even room temperature,is important.Supported Pt and Pd catalysts can completely convert HCHO at room temperature,but their industrial applications are limited because they are expensive.The catalytic activities in HCHO oxidation of transition-metal oxide catalysts such as manganese and cobalt oxides with unusual morphologies are better than those of traditional MnO2,Co3O4,or other metal oxides.This is attributed to their specific structures,high specific surface areas,and other factors such as active phase,reducibility,and amount of surface active oxygens.Such catalysts with various morphologies have great potential and can also be used as catalyst supports.The loading of relatively cheap Ag or Au on transition-metal oxides with special morphologies potentially improves the catalytic activity in HCHO removal at room temperature.The preparation and development of new nanocatalysts with various morphologies and structures is important for HCHO removal.In this paper,research progress on precious-metal and transition-metal oxide catalyst systems for HCHO oxidation is reviewed; topics such as oxidation properties,structure–activity relationships,and factors influencing the catalytic activity and reaction mechanism are discussed.Future prospects and directions for the development of such catalysts are also covered.
基金supported by the National Natural Science Foundation of China(21322202,21472187)the National Basic Research Program of China(2010CB833300)~~
文摘The selective oxidation of toluene and its derivatives is extremely important in the chemical industry.The use of photocatalysis in organic synthesis has attracted considerable attention among synthetic chemists because of its ＂green＂ environmental characteristics.In this study,nanoscale Bi_2WO_6with a flower-like morphology was found to be a highly efficient photocatalyst in the catalytic oxidation of toluene and its derivatives using O_2 as the oxidant.The loading of Pd nanoparticles as a cocatalyst onto the flower-like Bi_2WO_6 was found to produce a significant enhancement in the catalytic activity.Mechanistic investigation showed that the superior performance of Pd/Bi_2WO_6 could be attributed to the improvement of both the reductive and oxidative abilities of Bi_2WO_6 by the loading of the cocatalyst.
基金supported by the National Natural Science Foundation of China(21373037,21577013)China Postdoctoral Science Foundation(2014M560201)the Fundamental Research Funds for the Central Universities(DUT15TD49,DUT16ZD224)~~
文摘Gold stabilized on reducible oxide （CeO2 and FeOx） and irreducible oxide （γ‐Al2O3, SiO2, and HZSM‐5） were prepared by deposition precipitation method and tested for catalytic oxidation of formaldehyde （HCHO） at room temperature under high GHSV of 600000 ml/（g＆#183;s）. Au/γ‐Al2O3 cata‐lyst showed distinctive catalytic performance, presenting the highest initial HCHO conversion and stability. Correlating the reaction rate with Au particle size, there is a linear relationship, suggesting that the smaller Au particle size with higher dispersion possesses high reactivity for HCHO oxida‐tion. All the catalysts deactivated at high GHSV （600000 ml/（g＆#183;s））, but in a quite different rate. Re‐ducible oxide （CeO2 and FeOx） could stabilize gold through O linkage and therefore exhibits a better stability for HCHO oxidation reaction. However, the aggregation of gold particles occurred over Au/SiO2 and Au/HZSM‐5 catalysts, which result in the fast deactivation. Therefore, our results sug‐gest that the reducibility of the supports for Au catalysis has no direct influence on the activity, but affects the catalytic stability.
文摘Formaldehyde(HCHO) is a common indoor pollutant, long-term exposure to HCHO may harm human health. Its efficient removal at mild conditions is still challenging. The catalytic oxidation of HCHO molecules on a single atomic catalyst, Ti-decorated Ti3C2O2(Ti/Ti3C2O2) monolayer, is investigated by performing the first principles calculations in this work. It demonstrates that Ti atoms can be easily well dispersed at the form of single atom on Ti3C2O2 monolayer without aggregation. For HCHO catalytic oxidation, both Langmuir-Hinshelwood(LH) and Eley-Rideal(ER) mechanisms are considered. The results show that the step of HCHO dissociative adsorption on Ti/Ti3C2O2 with activated O2 can release high energy of 4.05 e V based on the ER mechanism, which can help to overcome the energy barrier(1.04 e V) of the subsequent reaction steps. The charge transfer from *OH group to CO molecule(dissociated from HCHO) not only promotes *OH group activation but also plays an important role in the H2 O generation along the ER mechanism. Therefore, HCHO can be oxidized easily on Ti/Ti3C2O2 monolayer, this work could provide significant guidance to develop effective non-noble metal catalysts for HCHO oxidation and broaden the applications of MXene-based materials.
基金Project(21576074)supported by the National Natural Science Foundation of China
文摘Rubidium phosphate can be more conveniently obtained by extracting trace Rb+ from the salt lake brine. Rb_3PO_4 was found to be an excellent heterogeneous catalyst for transfer hydrogenation. Rb_3PO_4 lost 70% of its active sites after adsorbing water, but the remaining was not affected. The reductions of aldehydes and ketones, when promoted by Rb_3PO_4, were allowed at room temperature. The activities of substrates at room temperature followed a descending order of 2,6-dichlorobenzaldehyde> 4-bromobenzaldehyde>benzaldehyde>acetophenone>anisaldehyde>butanone. A new catalytic cycle postulating a six-membered cyclic transition state for the reductions of aldehydes and ketones was proposed. These results exploited the catalytic usage of Rb_3PO_4 and worth in industrial application.
