Considering that cathode of microbial electrochemical system(MES)is a good electrons source for methane production via direct/indirect electron transfer to electroactive microorganisms,and that Fe(0)is also a confirme...Considering that cathode of microbial electrochemical system(MES)is a good electrons source for methane production via direct/indirect electron transfer to electroactive microorganisms,and that Fe(0)is also a confirmed electron donor for some electroactive microorganisms through metal-microbe direct electron transfer(DET),Fe(0)-cathode was equipped into an MES digester to enhance cathodic methane production.The results of this study indicated that the potential DET participator,Clostridium possibly obtained electrons directly from Fe(0)-cathode via metal-microbe electrons transfer,then transferred electrons directly to the definite DET participators,Methanosarcina/Methanothrix via microbemicrobe electrons transfer for CH_(4)production.In addition,Methanobacterium is another specially enriched methanogen on Fe(0)-cathode,which might obtain electrons directly from Fe(0)-cathode to produce CH_(4) via metal/electrode-microbe DET.The increment of conductivity of cathodic sludge in Fe(0)-cathode MES digester(R1)further confirmed the enrichment of electroactive microorganisms participating in DET process.As a consequence,a higher CH_(4) production(1205–1508 m L/d)and chemical oxygen demand(COD)removal(79.0%-93.8%)were achieved in R1 compared with graphite-cathode MES digester(R2,720–1090 m L/d and 63.6%-85.6%)and the conventional anaerobic digester(R3,384–428 m L/d and 35.2%-41.0%).In addition,energy efficiency calculated indicated that the output energy of CH_(4) production was 8.16 folds of electricity input in Fe(0)-cathode MES digester.展开更多
The direct electrochemical behavior between the glucose oxidase (GOD) and the multi walled carbon nanotubes (MWNTs) has been studied. Two pairs of cyclic voltammetric peaks corresponding to the two different processe...The direct electrochemical behavior between the glucose oxidase (GOD) and the multi walled carbon nanotubes (MWNTs) has been studied. Two pairs of cyclic voltammetric peaks corresponding to the two different processes, i.e. mass transport and surface reaction of GOD are observed on this MWNTs. The formal potentials with E o′=-0.45 V and E o′=-0.55 V were obtained respectively. The GOD film was observed on the carbon nanotube by the TEM.展开更多
Cyclic voltammetry is employed to demonstrate feasibility of direct electron transfer of glucose oxidase and D amino acid oxidase at a glassy carbon electrode in organic media. The reversible slight conformational ch...Cyclic voltammetry is employed to demonstrate feasibility of direct electron transfer of glucose oxidase and D amino acid oxidase at a glassy carbon electrode in organic media. The reversible slight conformational change of glucose oxidase is observed by changing 0.1 mol/L phosphate buffer to acetonitrile containing 10% v/v of water and 0.05 mol/L tetrabutyalammonium perchlorate, and vice versa.展开更多
The photocatalytic activity of CdS can be greatly improved by co-modification of NiS and TiO_2 materials; furthermore the order of connection affects much. A directional electron transfer route via CdS → TiO_2→ NiS ...The photocatalytic activity of CdS can be greatly improved by co-modification of NiS and TiO_2 materials; furthermore the order of connection affects much. A directional electron transfer route via CdS → TiO_2→ NiS is found crucial to the enhancement of ternary catalyst, where TiO_2 acts as an electron reservoir and Ni S works as an effective cocatalyst. Cd S/TiO_2@Ni S with Ni S loaded on TiO_2 has an activity of H_2 evolution 2.5 times higher than NiS@Cd S/TiO_2 with Ni S pre-loaded on Cd S. Faster e-/h+separation rates is obtained of Cd S/TiO_2@Ni S under visible light than under extra UV light irradiation, which in turn demonstrates the importance of directional electron transfer route.展开更多
Extracellular electron transfer(EET)plays a critical role in bioelectrochemical processes,allowing cou-pling between microorganisms and extracellular solid-state electrodes,metals,or other cells in energy metabolism.P...Extracellular electron transfer(EET)plays a critical role in bioelectrochemical processes,allowing cou-pling between microorganisms and extracellular solid-state electrodes,metals,or other cells in energy metabolism.Previous studies have suggested a role for outer-surface c-type cytochromes in direct metal-to-microbe electron transfer by Geobacter sulfurreducens,a model electroactive bacterium.Here,we ex-amined the possibility of other microbially produced electrical contacts by deleting the gene for PilA,the protein monomer that G.sulfurreducens assembles into electrically conductive protein nanowires(e-pili).Deleting pilA gene inhibited electron extraction from pure iron and 316L stainless steel up to 31%and 81%,respectively more than deleting the gene for the outer-surface cytochrome OmcS.This PilA-deficient phenotype,and the observation that relatively thick biofilms(21.7μm)grew on the metal surfaces at multi-cell distances from the metal surfaces suggest that e-pili contributed significantly to microbial cor-rosion via direct metal-to-microbe electron transfer.These results have implications for the fundamental understanding of electron harvest via e-pili by electroactive microbes,their uses in bioenergy production,as well as in monitoring and mitigation of metal biocorrosion.展开更多
he electrochemistry of cytochrome C was investigated at a spectrographicgraphite electrode. In phosphate buffer solution (pH= 7. 0) , cytochrome C showedstable and quasi-reversible response. The formal potential E￣(o...he electrochemistry of cytochrome C was investigated at a spectrographicgraphite electrode. In phosphate buffer solution (pH= 7. 0) , cytochrome C showedstable and quasi-reversible response. The formal potential E￣(o') was 0. 015 V (at25℃ , vs. SCE) and the heterogeneous electron transfer rate constant k_s obtainedvaried form 1. 10×10￣(-3) cm · s￣(-1) to 1. 80k×10￣(-3) cm · s￣(-1). The thermodynamic pa-rameters of the electron transfer reaction of cvtochrome C was also estimated. Fur-thermore, the effect of the various electrode surface states on the electrochemistryof cytochrome C was discussed.展开更多
To improve anaerobic digestion(AD)efficiency of rice straw,solid alkaline CaO and the liquid fraction of digestate(LFD)were used as pretreatment agents of rice straw.The results showed that AD performance of rice stra...To improve anaerobic digestion(AD)efficiency of rice straw,solid alkaline CaO and the liquid fraction of digestate(LFD)were used as pretreatment agents of rice straw.The results showed that AD performance of rice straw with CaOLFD pretreatment was optimal in different pretreatment methods of the CaO+LFD,CaOLFD,LFD+CaO,CaO,and LFD.The maximum methane yield(314 ml(g VS)^(-1))and the highest VFAs concentration(14851 mg·L^(-1) on day 3)of the CaOLFD pretreatment group were 81%and 118%higher than that of the control group,respectively.Under the action of solid alkaline CaO,the bacteria of Clostridium,Atopostipes,Sphaerochaeta,Tissierella,Thiopseudomonas,Rikenellaceae,and Sedimentibacter could build up co-cultures with the archaeal of Methanosaeta,Methanobacterium,and Methanosarcina performing direct interspecies electron transfer(DIET)and improving AD performance of rice straw.Therefore,the combined pretreatment using CaO and LFD could not only pretreat rice straw but also stimulate co-cultures of microorganism to establish DIET enhancing AD efficiency.展开更多
Given the increasing number of diabetic patients,rapid and accurate detection of glucose in body fluids is critical.This study developed a direct electrochemical biosensor for glucose based on nitrogen-doped carbon na...Given the increasing number of diabetic patients,rapid and accurate detection of glucose in body fluids is critical.This study developed a direct electrochemical biosensor for glucose based on nitrogen-doped carbon nanocages(NCNCs).NCNCs possess a large specific surface area of 1395 m^(2)·g^(-1),a high N atomic content of 9.37%and good biocompatibility,which is favorable for enzyme loading and electron transfer.The surface average concentration of electroactive glucose oxidase on NCNCs was 2.82×10^(-10)mol·cm^(-2).The NCNC-based direct electrochemical biosensor exhibited a high sensitivity of 13.7μA·(mmol·L^(-1))^(-1)·cm^(-2),rapid response time of 5 s and an impressive electron-transferrate constant(ks)of 1.87 s^(-1).Furthermore,we investigated an NCNC-based direct electron transfer(DET)biosensor for sweat glucose detection,which demonstrated tremendous promise for non-invasive wearable diabetes diagnosis.展开更多
Direct electrochemistry and electrocatalysis of myoglobin（Mb） were studied with Mb immobilized on dodecyltrimethylammonium bromide（DTAB） film modified carbon ceramic（CC） electrode.Cyclic voltammetry showed a pai...Direct electrochemistry and electrocatalysis of myoglobin（Mb） were studied with Mb immobilized on dodecyltrimethylammonium bromide（DTAB） film modified carbon ceramic（CC） electrode.Cyclic voltammetry showed a pair of well-defined and nearly reversible redox peaks of Mb（Fe~Ⅱ/Fe~Ⅲ） at about—0.3 V vs.SCE（pH = 6.98）.The currents of the redox peak were linear to scan rate,and rate constant（Ks） was estimated to be 3.03 s^（-1）.The formal potential（E°＇） of Mb in the DTAB/CC electrodes shifted linearly with pH with a slope of -36.44 mV/pH,implying that the electron transfer between DTAB and CC electrodes is accompanied by proton transportation.The immobilized Mb exhibited excellent electrocatalytic response to the reduction of hydrogen peroxide（H2O2）.展开更多
Conductive additive such as biochar have been extensively employed to enhance anaerobic digestion(AD)performance for over a decade.Among the proposed mechanisms,conductive additive-facilitated direct interspecies elec...Conductive additive such as biochar have been extensively employed to enhance anaerobic digestion(AD)performance for over a decade.Among the proposed mechanisms,conductive additive-facilitated direct interspecies electron transfer(DIET)is frequently cited as a key contributor to these performance improvements.Because this process is believed to bypass traditional diffusible intermediates(e.g.,H_(2) or formate),it can enable more efficient energy transfer between syntrophic partners and accelerate substrate degradation,potentially leading to higher methane yields and improved overall stability of the anaerobic digestion process.However,benefits regarding conductive additivefacilitated DIET often rely on indirect indicators rather than direct experimental evidence.Here,we advocate for a critical reassessment on the benefits of conductive additive for DIET in AD.Specifically,we emphasize the importance of establishing standardized experimental protocols and obtaining direct evidence to confirm the occurrence and significance of DIET in conductive additive-amended AD system.Furthermore,it is essential to distinguish DIET from other enhancement mechanisms such as pH buffering and toxin adsorption that may independently contribute to improved AD performance,with the goal of advancing its practical implementation.展开更多
针对微生物种间电子转移效率低会影响厌氧消化甲烷产量的问题,以餐厨垃圾压榨液为基质,将导电材料生物炭加入厌氧发酵体系中,综合考察生物炭粒径对体系直接种间电子转移(direct interspecies electron transfer,DIET)和产甲烷能力的影...针对微生物种间电子转移效率低会影响厌氧消化甲烷产量的问题,以餐厨垃圾压榨液为基质,将导电材料生物炭加入厌氧发酵体系中,综合考察生物炭粒径对体系直接种间电子转移(direct interspecies electron transfer,DIET)和产甲烷能力的影响。结果表明,随着生物炭粒径的增大,体系的最大产甲烷潜能先增大再减小,40~80目为生物炭最佳粒径,其最大产甲烷潜能和滞后期分别提升17.09%、缩短21.74%。污泥特性分析表明,生物炭能够在厌氧产甲烷过程中建立DIET途径,最佳粒径组的电导率、ETS活性和辅酶F_(420)浓度分别为空白组的1.04、1.46和2.51倍。微生物分析表明,生物炭使得Proteobacteria、Chloroflexi、Methanoculleus和Methanosarcina的相对丰度提高了86.56%、71.62%、27.16%和337.87%,说明生物炭在微生物间成功构建了DIET通道,进而增加了厌氧发酵过程的累积产甲烷量。展开更多
厌氧消化是目前实现城市污泥减量化和资源化的重要途径之一。然而传统厌氧消化受氢气/甲酸扩散的限制,代谢容易受阻,最终导致厌氧消化体系酸化崩溃。直接种间电子传递(Direct Interspecies Electron Transfer,DIET)被证实能够有效地避...厌氧消化是目前实现城市污泥减量化和资源化的重要途径之一。然而传统厌氧消化受氢气/甲酸扩散的限制,代谢容易受阻,最终导致厌氧消化体系酸化崩溃。直接种间电子传递(Direct Interspecies Electron Transfer,DIET)被证实能够有效地避免上述问题并提高厌氧消化的效能。研究表明,添加少量丙三醇可富集电活性微生物,促进DIET。然而添加外源丙三醇会增加运行成本。本实验结合碱预处理与酵母发酵,实现城市污泥自产丙三醇促进DIET,为城市污泥高效厌氧产甲烷提供技术支持。研究结果显示:(1)碱预处理的最佳周期为10 h,城市污泥中溶解性糖的含量提高了43.4%;酵母的最佳接种量为10%,最佳发酵周期为9 h,丙三醇浓度占城市污泥总化学需氧量(COD)的2.43%;(2)相比于对照组,酵母发酵组和碱预处理联合酵母发酵组的甲烷产量分别提高了11.8%和15.4%,挥发性固体(VS)去除率几乎相同(约45%),有机质转化效率分别提高了5.80%和9.30%;(3)相比于对照组,酵母发酵组和碱预处理联合酵母发酵组污泥的放电电子转移系数(Electron Transfer Coefficient,ETC)提高了11.1%和16.8%,充电ETC提高了11.1%和17.3%;(4)微生物群落分析发现,碱预处理联合酵母发酵组相比于对照组富集了可能参与DIET的Methanothrix soehngenii GP6和Fastidiosipila sanguinis。展开更多
基金the financial support from the National Natural Scientific Foundation of China(No.52000020)the National Natural Scientific Foundation of China(No.21876022)。
文摘Considering that cathode of microbial electrochemical system(MES)is a good electrons source for methane production via direct/indirect electron transfer to electroactive microorganisms,and that Fe(0)is also a confirmed electron donor for some electroactive microorganisms through metal-microbe direct electron transfer(DET),Fe(0)-cathode was equipped into an MES digester to enhance cathodic methane production.The results of this study indicated that the potential DET participator,Clostridium possibly obtained electrons directly from Fe(0)-cathode via metal-microbe electrons transfer,then transferred electrons directly to the definite DET participators,Methanosarcina/Methanothrix via microbemicrobe electrons transfer for CH_(4)production.In addition,Methanobacterium is another specially enriched methanogen on Fe(0)-cathode,which might obtain electrons directly from Fe(0)-cathode to produce CH_(4) via metal/electrode-microbe DET.The increment of conductivity of cathodic sludge in Fe(0)-cathode MES digester(R1)further confirmed the enrichment of electroactive microorganisms participating in DET process.As a consequence,a higher CH_(4) production(1205–1508 m L/d)and chemical oxygen demand(COD)removal(79.0%-93.8%)were achieved in R1 compared with graphite-cathode MES digester(R2,720–1090 m L/d and 63.6%-85.6%)and the conventional anaerobic digester(R3,384–428 m L/d and 35.2%-41.0%).In addition,energy efficiency calculated indicated that the output energy of CH_(4) production was 8.16 folds of electricity input in Fe(0)-cathode MES digester.
文摘The direct electrochemical behavior between the glucose oxidase (GOD) and the multi walled carbon nanotubes (MWNTs) has been studied. Two pairs of cyclic voltammetric peaks corresponding to the two different processes, i.e. mass transport and surface reaction of GOD are observed on this MWNTs. The formal potentials with E o′=-0.45 V and E o′=-0.55 V were obtained respectively. The GOD film was observed on the carbon nanotube by the TEM.
文摘Cyclic voltammetry is employed to demonstrate feasibility of direct electron transfer of glucose oxidase and D amino acid oxidase at a glassy carbon electrode in organic media. The reversible slight conformational change of glucose oxidase is observed by changing 0.1 mol/L phosphate buffer to acetonitrile containing 10% v/v of water and 0.05 mol/L tetrabutyalammonium perchlorate, and vice versa.
基金Supported by the Scientific Research Starting Foundation for Doctors(trxyD H1512)the Foundation for Youth Talent Growth Project in the Ministry of Science and Technology of China(20171184)the Mutual Foundation in the Ministry of Science and Technology of China(20177315)
文摘The photocatalytic activity of CdS can be greatly improved by co-modification of NiS and TiO_2 materials; furthermore the order of connection affects much. A directional electron transfer route via CdS → TiO_2→ NiS is found crucial to the enhancement of ternary catalyst, where TiO_2 acts as an electron reservoir and Ni S works as an effective cocatalyst. Cd S/TiO_2@Ni S with Ni S loaded on TiO_2 has an activity of H_2 evolution 2.5 times higher than NiS@Cd S/TiO_2 with Ni S pre-loaded on Cd S. Faster e-/h+separation rates is obtained of Cd S/TiO_2@Ni S under visible light than under extra UV light irradiation, which in turn demonstrates the importance of directional electron transfer route.
基金supported by the National Natu-ral Science Foundation of China(Nos.U2006219 and 52101078)China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202120)+2 种基金the National Key Research and Development Pro-gram of China(No.2020YFA0907300)the Fundamental Research Funds for the Central Universities of the Ministry of Education of China(Nos.N2102009 and N2002019)the Liaoning Revitaliza-tion Talents Program(No.XLYC1907158).
文摘Extracellular electron transfer(EET)plays a critical role in bioelectrochemical processes,allowing cou-pling between microorganisms and extracellular solid-state electrodes,metals,or other cells in energy metabolism.Previous studies have suggested a role for outer-surface c-type cytochromes in direct metal-to-microbe electron transfer by Geobacter sulfurreducens,a model electroactive bacterium.Here,we ex-amined the possibility of other microbially produced electrical contacts by deleting the gene for PilA,the protein monomer that G.sulfurreducens assembles into electrically conductive protein nanowires(e-pili).Deleting pilA gene inhibited electron extraction from pure iron and 316L stainless steel up to 31%and 81%,respectively more than deleting the gene for the outer-surface cytochrome OmcS.This PilA-deficient phenotype,and the observation that relatively thick biofilms(21.7μm)grew on the metal surfaces at multi-cell distances from the metal surfaces suggest that e-pili contributed significantly to microbial cor-rosion via direct metal-to-microbe electron transfer.These results have implications for the fundamental understanding of electron harvest via e-pili by electroactive microbes,their uses in bioenergy production,as well as in monitoring and mitigation of metal biocorrosion.
文摘he electrochemistry of cytochrome C was investigated at a spectrographicgraphite electrode. In phosphate buffer solution (pH= 7. 0) , cytochrome C showedstable and quasi-reversible response. The formal potential E￣(o') was 0. 015 V (at25℃ , vs. SCE) and the heterogeneous electron transfer rate constant k_s obtainedvaried form 1. 10×10￣(-3) cm · s￣(-1) to 1. 80k×10￣(-3) cm · s￣(-1). The thermodynamic pa-rameters of the electron transfer reaction of cvtochrome C was also estimated. Fur-thermore, the effect of the various electrode surface states on the electrochemistryof cytochrome C was discussed.
基金supported by the National Key Research&Development Program of Ministry of Science and Technology of the People’s Republic of China(grant number 2018YFC1900901).
文摘To improve anaerobic digestion(AD)efficiency of rice straw,solid alkaline CaO and the liquid fraction of digestate(LFD)were used as pretreatment agents of rice straw.The results showed that AD performance of rice straw with CaOLFD pretreatment was optimal in different pretreatment methods of the CaO+LFD,CaOLFD,LFD+CaO,CaO,and LFD.The maximum methane yield(314 ml(g VS)^(-1))and the highest VFAs concentration(14851 mg·L^(-1) on day 3)of the CaOLFD pretreatment group were 81%and 118%higher than that of the control group,respectively.Under the action of solid alkaline CaO,the bacteria of Clostridium,Atopostipes,Sphaerochaeta,Tissierella,Thiopseudomonas,Rikenellaceae,and Sedimentibacter could build up co-cultures with the archaeal of Methanosaeta,Methanobacterium,and Methanosarcina performing direct interspecies electron transfer(DIET)and improving AD performance of rice straw.Therefore,the combined pretreatment using CaO and LFD could not only pretreat rice straw but also stimulate co-cultures of microorganism to establish DIET enhancing AD efficiency.
基金financially supported by National Key Research and Development Program of China(No.2021YFA1401103)the National Natural Science Foundation of China(Nos.61825403,61921005 and 61904049)。
文摘Given the increasing number of diabetic patients,rapid and accurate detection of glucose in body fluids is critical.This study developed a direct electrochemical biosensor for glucose based on nitrogen-doped carbon nanocages(NCNCs).NCNCs possess a large specific surface area of 1395 m^(2)·g^(-1),a high N atomic content of 9.37%and good biocompatibility,which is favorable for enzyme loading and electron transfer.The surface average concentration of electroactive glucose oxidase on NCNCs was 2.82×10^(-10)mol·cm^(-2).The NCNC-based direct electrochemical biosensor exhibited a high sensitivity of 13.7μA·(mmol·L^(-1))^(-1)·cm^(-2),rapid response time of 5 s and an impressive electron-transferrate constant(ks)of 1.87 s^(-1).Furthermore,we investigated an NCNC-based direct electron transfer(DET)biosensor for sweat glucose detection,which demonstrated tremendous promise for non-invasive wearable diabetes diagnosis.
基金supported by the Shaanxi Provincial Natural Science Foundation for Young Scientist(No. 2009JQ2011)the Shaanxi Provincial Education Department Foundation(No.08JK322)+1 种基金the Youth Science and Technology Foundation of Xi'an University of Architecture and Technology(No.QN0620)Youth Scientist Foundation of Xi'an University of Architecture and Technology(No.RC0942)
文摘Direct electrochemistry and electrocatalysis of myoglobin（Mb） were studied with Mb immobilized on dodecyltrimethylammonium bromide（DTAB） film modified carbon ceramic（CC） electrode.Cyclic voltammetry showed a pair of well-defined and nearly reversible redox peaks of Mb（Fe~Ⅱ/Fe~Ⅲ） at about—0.3 V vs.SCE（pH = 6.98）.The currents of the redox peak were linear to scan rate,and rate constant（Ks） was estimated to be 3.03 s^（-1）.The formal potential（E°＇） of Mb in the DTAB/CC electrodes shifted linearly with pH with a slope of -36.44 mV/pH,implying that the electron transfer between DTAB and CC electrodes is accompanied by proton transportation.The immobilized Mb exhibited excellent electrocatalytic response to the reduction of hydrogen peroxide（H2O2）.
基金National Natural Science Foundation of China(Nos.52200074 and 52192684)the Fundamental Research Funds for the Central Universities(No.21625309)for supporting this work.
文摘Conductive additive such as biochar have been extensively employed to enhance anaerobic digestion(AD)performance for over a decade.Among the proposed mechanisms,conductive additive-facilitated direct interspecies electron transfer(DIET)is frequently cited as a key contributor to these performance improvements.Because this process is believed to bypass traditional diffusible intermediates(e.g.,H_(2) or formate),it can enable more efficient energy transfer between syntrophic partners and accelerate substrate degradation,potentially leading to higher methane yields and improved overall stability of the anaerobic digestion process.However,benefits regarding conductive additivefacilitated DIET often rely on indirect indicators rather than direct experimental evidence.Here,we advocate for a critical reassessment on the benefits of conductive additive for DIET in AD.Specifically,we emphasize the importance of establishing standardized experimental protocols and obtaining direct evidence to confirm the occurrence and significance of DIET in conductive additive-amended AD system.Furthermore,it is essential to distinguish DIET from other enhancement mechanisms such as pH buffering and toxin adsorption that may independently contribute to improved AD performance,with the goal of advancing its practical implementation.
文摘针对微生物种间电子转移效率低会影响厌氧消化甲烷产量的问题,以餐厨垃圾压榨液为基质,将导电材料生物炭加入厌氧发酵体系中,综合考察生物炭粒径对体系直接种间电子转移(direct interspecies electron transfer,DIET)和产甲烷能力的影响。结果表明,随着生物炭粒径的增大,体系的最大产甲烷潜能先增大再减小,40~80目为生物炭最佳粒径,其最大产甲烷潜能和滞后期分别提升17.09%、缩短21.74%。污泥特性分析表明,生物炭能够在厌氧产甲烷过程中建立DIET途径,最佳粒径组的电导率、ETS活性和辅酶F_(420)浓度分别为空白组的1.04、1.46和2.51倍。微生物分析表明,生物炭使得Proteobacteria、Chloroflexi、Methanoculleus和Methanosarcina的相对丰度提高了86.56%、71.62%、27.16%和337.87%,说明生物炭在微生物间成功构建了DIET通道,进而增加了厌氧发酵过程的累积产甲烷量。
