The electrocatalytic oxidation of 5-hydroxymethylfurfural(HMF)offers a promising approach for producing high-value chemicals and hydrogen.While cobalt-based oxides are promising catalysts for the HMF oxidation reactio...The electrocatalytic oxidation of 5-hydroxymethylfurfural(HMF)offers a promising approach for producing high-value chemicals and hydrogen.While cobalt-based oxides are promising catalysts for the HMF oxidation reaction(HMFOR),their performance is limited by inefficient oxidation of CoO_(x)to the active CoO_(2)phase.Here,we demonstrate that introducing oxygen vacancies into CoO_(x)significantly enhances its oxidation kinetics.The oxygen vacancy-rich CoO_(x)supported on copper foam(CoO_(x)/CF)achieves an impressive 98%HMF conversion with a Faradaic efficiency of 98.6%at 1.5 V vs.RHE.Operando Raman spectroscopy reveals that oxygen vacancies facilitate the preferential formation ofγ-CoOOH overβ-CoOOH during electrocatalysis,thereby promoting the generation of the active CoO_(2)phase.Combining in situ infrared spectroscopy with density functional theory(DFT)calculations,we unambiguously establish the reaction pathway,which proceeds via the sequence of HMF→5-hydroxymethyl-2-fur ancarboxylic acid(HMFCA)→2-formyl-5-furancarboxylic acid(FFCA)→2,5-furandicarboxylic acid(FDCA),and reveal the pivotal role of the active CoO_(2)species in accelerating hydroxyl radical oxidation.This work not only provides fundamental mechanistic insights into oxygen vacancy-mediated catalyst design but also offers a novel strategy for developing high-performance transition metal oxide electrocatalysts for biomass valorization.展开更多
In this paper,we introduce the notion of G_(C)-X-injective modules,where X denotes a class of left S-modules and C represents a faithfully semidualizing bimodule.Under the condition that X satisfies certain hypotheses...In this paper,we introduce the notion of G_(C)-X-injective modules,where X denotes a class of left S-modules and C represents a faithfully semidualizing bimodule.Under the condition that X satisfies certain hypotheses,some properties and some equivalent characterizations of G_(C)-X-injective modules are investigated,and we also show that the triple(■,cores■,■)is a weak co-AB-context.As an application,two complete cotorsion pairs and a new model structure in Mod S are given.展开更多
In order to prevent the emission of NO_(x) from diesel engines during the cold-start period,a NO_(x) adsorption selective catalytic reduction(AdSCR)catalyst was prepared by combining a selective catalytic reduction(SC...In order to prevent the emission of NO_(x) from diesel engines during the cold-start period,a NO_(x) adsorption selective catalytic reduction(AdSCR)catalyst was prepared by combining a selective catalytic reduction(SCR)catalyst with an NO_(x) adsorbent.In this study,CeO_(2)/Al_(2)O_(3)(Ce/Al)was employed as the NO_(x) adsorbent,combined with WO_(3)/CeZrO_(x)(W/CZ)as a promising SCR catalyst,to prepare an AdSCR catalyst.The characterization results demonstrate that the synergistic effects of the combined catalyst significantly enhance the activated oxidation of NO_(x) in comparison to the individual catalysts.The addition of Ce/Al enhances the adsorption of NO_(x) on the catalysts,which is then reduced to N_(2) and H_(2)O by NH_(3) under the action of W/CZ catalysts.The results of the NH_(3)-SCR activity test indicate that an excess of Ce/Al results in a reduction in SCR performance,suggesting that there is a balance between the SCR component and the NO_(x) adsorbent.The optimal combination of 20 wt%Ce/Al+W/CZ(20CA-W/CZ)catalyst demonstrates enhanced NO_(x) adsorption-storage performance while maintaining the exceptional NH_(3)-SCR performance.The NO_(x) complete storage time of the 20CA-W/CZ catalyst is 125 s,which is nearly twice as long as that of the Ce/Al and W/CZ catalysts.Furthermore,the NO_(x) conversion of the 20CA-W/CZ catalyst at low temperatures is approximately 10%higher than that of the W/CZ catalyst.The findings of this study offer a promising s trategy for the design of high-performance AdSCR catalysts in the future.展开更多
Manganese-oxidizing microbes are capable of oxidizing Mn(Ⅱ) to manganese oxides through direct enzymatic and indirect mechanisms.However,bacterial Mn(Ⅱ) oxidation in alkaline environment remains unclear.This study i...Manganese-oxidizing microbes are capable of oxidizing Mn(Ⅱ) to manganese oxides through direct enzymatic and indirect mechanisms.However,bacterial Mn(Ⅱ) oxidation in alkaline environment remains unclear.This study isolated an alkali-tolerant bacterium Pseudorhizobium flavum MXJ-1 from marine surface sediments that can oxidize Mn(Ⅱ) to biogenic manganese oxides(BioMnO_(x)).Characterization of BioMnO_(x) reveals that rod-shaped bacterial cells produce amorphous BioMnO_(x) containing mixed valences of Mn.The effects of different pH,carbon and nitrogen sources,metal ions on growth and Mn(Ⅱ) oxidation activity of strain MXJ-1 were investigated.Results elucidate that strain MXJ-1 adapts to a broad range of pH from 5.0 to 10.0,achieves a maximum Mn(Ⅱ) oxidation percentage of 69.41 %,but there is no significant correlation between biomass and Mn(Ⅱ) oxidation.Cu(Ⅱ) inhibited Mn(Ⅱ) oxidation at concentration as low as 20 μmol/L,and Mn(Ⅱ) oxidation decreased with Mn(Ⅱ) levels increasing to 500 μmol/L.Genomic analysis identified two genes encoding animal heme peroxidases(AHPs) and three encoding dihydrolipoyl dehydrogenases(DLDHs),highlighting the potential role of superoxide in Mn(Ⅱ) oxidation.Several alkali-tolerance genes,including those encoding Na+/H+ antiporter,were also identified,which probably associated with alkali-tolerance of MXJ-1.Superoxide detection by nitro blue tetrazolium(NBT) assay indicates it involved in Mn(Ⅱ) oxidation.This study isolated a Mn(Ⅱ)-oxidizing,alkali-tolerant bacterium,expanding insights into microbial Mn(Ⅱ) oxidation in extreme environments.展开更多
基金financial support from the National Natural Science Foundation of China(Nos.22308246,22478278)the Central Government Guides the Local Science and Technology Development Special Fund(No.YDZJSX20231A015)the Fundamental Research Program of Shanxi Province(No.202203021212266)。
文摘The electrocatalytic oxidation of 5-hydroxymethylfurfural(HMF)offers a promising approach for producing high-value chemicals and hydrogen.While cobalt-based oxides are promising catalysts for the HMF oxidation reaction(HMFOR),their performance is limited by inefficient oxidation of CoO_(x)to the active CoO_(2)phase.Here,we demonstrate that introducing oxygen vacancies into CoO_(x)significantly enhances its oxidation kinetics.The oxygen vacancy-rich CoO_(x)supported on copper foam(CoO_(x)/CF)achieves an impressive 98%HMF conversion with a Faradaic efficiency of 98.6%at 1.5 V vs.RHE.Operando Raman spectroscopy reveals that oxygen vacancies facilitate the preferential formation ofγ-CoOOH overβ-CoOOH during electrocatalysis,thereby promoting the generation of the active CoO_(2)phase.Combining in situ infrared spectroscopy with density functional theory(DFT)calculations,we unambiguously establish the reaction pathway,which proceeds via the sequence of HMF→5-hydroxymethyl-2-fur ancarboxylic acid(HMFCA)→2-formyl-5-furancarboxylic acid(FFCA)→2,5-furandicarboxylic acid(FDCA),and reveal the pivotal role of the active CoO_(2)species in accelerating hydroxyl radical oxidation.This work not only provides fundamental mechanistic insights into oxygen vacancy-mediated catalyst design but also offers a novel strategy for developing high-performance transition metal oxide electrocatalysts for biomass valorization.
文摘In this paper,we introduce the notion of G_(C)-X-injective modules,where X denotes a class of left S-modules and C represents a faithfully semidualizing bimodule.Under the condition that X satisfies certain hypotheses,some properties and some equivalent characterizations of G_(C)-X-injective modules are investigated,and we also show that the triple(■,cores■,■)is a weak co-AB-context.As an application,two complete cotorsion pairs and a new model structure in Mod S are given.
基金Project supported by the National Natural Science Foundation of China(22072098)the Sichuan Science and Technology Program(2022ZHCG0125)。
文摘In order to prevent the emission of NO_(x) from diesel engines during the cold-start period,a NO_(x) adsorption selective catalytic reduction(AdSCR)catalyst was prepared by combining a selective catalytic reduction(SCR)catalyst with an NO_(x) adsorbent.In this study,CeO_(2)/Al_(2)O_(3)(Ce/Al)was employed as the NO_(x) adsorbent,combined with WO_(3)/CeZrO_(x)(W/CZ)as a promising SCR catalyst,to prepare an AdSCR catalyst.The characterization results demonstrate that the synergistic effects of the combined catalyst significantly enhance the activated oxidation of NO_(x) in comparison to the individual catalysts.The addition of Ce/Al enhances the adsorption of NO_(x) on the catalysts,which is then reduced to N_(2) and H_(2)O by NH_(3) under the action of W/CZ catalysts.The results of the NH_(3)-SCR activity test indicate that an excess of Ce/Al results in a reduction in SCR performance,suggesting that there is a balance between the SCR component and the NO_(x) adsorbent.The optimal combination of 20 wt%Ce/Al+W/CZ(20CA-W/CZ)catalyst demonstrates enhanced NO_(x) adsorption-storage performance while maintaining the exceptional NH_(3)-SCR performance.The NO_(x) complete storage time of the 20CA-W/CZ catalyst is 125 s,which is nearly twice as long as that of the Ce/Al and W/CZ catalysts.Furthermore,the NO_(x) conversion of the 20CA-W/CZ catalyst at low temperatures is approximately 10%higher than that of the W/CZ catalyst.The findings of this study offer a promising s trategy for the design of high-performance AdSCR catalysts in the future.
基金supported by the National Natural Science Foundation of China(No.42277107)Liaoning Province Natural Science Foundation Joint Funds(Ph.D.Scientific Research Program)(No.2023-BSBA-024/DUT24BS004)the Open Project of State Key Laboratory of Urban Water Resource and Environment,China,Harbin Institute of Technology(No.HC202330)。
文摘Manganese-oxidizing microbes are capable of oxidizing Mn(Ⅱ) to manganese oxides through direct enzymatic and indirect mechanisms.However,bacterial Mn(Ⅱ) oxidation in alkaline environment remains unclear.This study isolated an alkali-tolerant bacterium Pseudorhizobium flavum MXJ-1 from marine surface sediments that can oxidize Mn(Ⅱ) to biogenic manganese oxides(BioMnO_(x)).Characterization of BioMnO_(x) reveals that rod-shaped bacterial cells produce amorphous BioMnO_(x) containing mixed valences of Mn.The effects of different pH,carbon and nitrogen sources,metal ions on growth and Mn(Ⅱ) oxidation activity of strain MXJ-1 were investigated.Results elucidate that strain MXJ-1 adapts to a broad range of pH from 5.0 to 10.0,achieves a maximum Mn(Ⅱ) oxidation percentage of 69.41 %,but there is no significant correlation between biomass and Mn(Ⅱ) oxidation.Cu(Ⅱ) inhibited Mn(Ⅱ) oxidation at concentration as low as 20 μmol/L,and Mn(Ⅱ) oxidation decreased with Mn(Ⅱ) levels increasing to 500 μmol/L.Genomic analysis identified two genes encoding animal heme peroxidases(AHPs) and three encoding dihydrolipoyl dehydrogenases(DLDHs),highlighting the potential role of superoxide in Mn(Ⅱ) oxidation.Several alkali-tolerance genes,including those encoding Na+/H+ antiporter,were also identified,which probably associated with alkali-tolerance of MXJ-1.Superoxide detection by nitro blue tetrazolium(NBT) assay indicates it involved in Mn(Ⅱ) oxidation.This study isolated a Mn(Ⅱ)-oxidizing,alkali-tolerant bacterium,expanding insights into microbial Mn(Ⅱ) oxidation in extreme environments.
