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1.
Small ; 20(13): e2306697, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37963857

RESUMO

Bismuth chalcogenides are used as cathode materials in Zn-proton hybrid ion batteries, which exhibit an ultraflat discharge plateau that is favorable for practical applications. Unfortunately, their capacity is not competitive, and their charge storage mechanisms are ambiguous, both of which hinder their further development. In this study, S-doped Bi2Te3- x (SBT) nanosheets are prepared by tellurizing a Bi2O2S precursor using a hydrothermal process. As revealed by density functional theory analyses, the S dopant and its induced Te vacancies can distinctly manipulate the electronic structure of SBT, resulting in decent electrical conductivity and more negative adsorption energy to Zn2+. These advantages boost the Zn2+ storage ability of SBT materials. Consequently, compared with defect-free Bi2Te3, the SBT cathodes have superior specific capacity, rate capability, and cycling stability.

2.
Chemphyschem ; : e202400312, 2024 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-39004605

RESUMO

Developing highly superior precious-metal-free electrocatalysts for oxygen reduction reaction (ORR) are challenging and great significance. In this study, it is reported that an efficient ORR catalysts with N and S co-doped carbon nanotubes anchored to copper (Cu) nanoclusters by mechanical grinding and high temperature heat treatment. The obtained Cu-S1-N-C electrocatalysts exhibited a high ORR performance with an onset potential (Eonest) of 0.989 V and a half-wave potential (E1/2) of 0.905 V (vs. RHE) in alkaline electrolyte, which was superior to that of commercial Pt/C catalyst. In contrast to N doping alone, the defect structures and active species of the catalysts were optimized by precise modulation of S-atom doping, and moreover, the introduction of S-atoms provided more thiophene-sulfur active sites. This study provides an innovative idea for designing excellent ORR catalysts.

3.
Nanotechnology ; 35(17)2024 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-38334144

RESUMO

Boron nitride quantum dots (BNQDs) have emerged as promising photocatalysts due to their excellent physicochemical properties. This study investigates strategies to enhance the photocatalytic performance of BNQDs through sulfur-doping (S-BNQDs) and edge-functionalization with ligands (urea, thiourea, p-phenyl-enediamine (PPD)). To analyze the geometry, electronic structure, optical absorption, charge transfer, and photocatalytic parameters of pristine and functionalized S-BNQDs, we performed density functional theory calculations. The results showed that S-doping and ligand functionalization tune the bandgap, band energies, and introduce mid-gap states to facilitate light absorption, charge separation, and optimized energetics for photocatalytic redox reactions. Notably, the PPD ligand induced the most substantial bandgap narrowing and absorption edge red-shift by over 1 electron volt (eV) compared to pristine S-BNQD, significantly expanding light harvesting. Additionally, urea and PPD functionalization increased the charge transfer length by up to 2.5 times, effectively reducing recombination. On the other hand, thiourea functionalization yielded the most favorable electron injection energetics. The energy conversion efficiency followed the order: PPD (15.0%) > thiourea (12.0%) > urea (11.0%) > pristine (10.0%). Moreover, urea functionalization maximized the first-order hyperpolarizability, enhancing light absorption. These findings provide valuable insights into tailoring S-BNQDs through strategic doping and functionalization to develop highly efficient, customized photocatalysts for sustainable applications.

4.
Nanotechnology ; 35(22)2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38470062

RESUMO

In this study, S-CCO@Co(OH)2('CCO' representing CuCo2O4/Cu2O; 'S-'representing sulfur doping) was synthesized by hydrothermal method followed by electrodeposition. The multiple effects of S doping were studied by S doping and constructing 3D core-shell structure. S doping induced the reduction of Cu2+and Co3+to Cu+and Co2+, respectively. Also, S partially replaces O and creates oxygen vacancies, which increases a number of active sites for the redox reaction enhancing the redox reaction activity. After the electrodeposition, S-Co bond is formed between the Co(OH)2shell and the S-CCO core, which suggests a synergistic effect between S doping and core-shell structure. The formation of S-Co bond is conducive to electron and ion transport, thus improving electrochemical performance. After modification, the specific capacitance of S-CCO@Co(OH)2is 4.28 times higher than CCO, up to 1730 Fg-1. Furthermore, the assembled S-CCO@Co(OH)2//activated carbon supercapacitor exhibits an energy density of 83.89 Whkg-1at 848.81 Wkg-1and a retention rate of 98.48% after 5000 charge and discharge cycles. Therefore, S doping and its mutual effect with the utilization of the core-shell structure considerably enhanced the electrochemical performance of the CCO-based electrodes, endowing its potential in further application.

5.
Environ Sci Technol ; 58(1): 371-380, 2024 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-38146194

RESUMO

Cyclic desulfurization-regeneration-denitrification based on metal-free carbon materials is one of the most promising ways to remove NOx and SO2 simultaneously. However, the impact of S-doping induced by the cyclic desulfurization and regeneration (C-S-R) process on the selective catalytic reduction (SCR) is not well understood. Herein, it is demonstrated that the C-S-R process at 500 °C induces in situ S-doping with a significant accumulation of C-S-C structures. NOx conversion was dramatically enhanced from 18.95% of the original sample to 84.55% of the S-doped sample. Density functional theory calculations revealed that the C-S-C structure significantly regulates the electronic structure of the C atom adjacent to the ketonic carbonyl group, thereby significantly altering the NH3 adsorption configuration with superior adsorption capacity. Moreover, S-doping induces an extra electron transfer between the N atom of the NH3 molecule and the C atom of the carbon plane, thereby promoting the activation of NH3 over the ketonic carbonyl group with a reduced energy barrier. This study elucidates a synergetic promotional mechanism between the ketonic carbonyl group and the C-S-C structure for SCR, offering a novel design strategy for high-performance heteroatom-doped carbon catalysts in industrial applications.


Assuntos
Amônia , Carbono , Oxirredução , Amônia/química , Metais , Titânio , Catálise
6.
Small ; 19(28): e2301116, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37191326

RESUMO

Although challenges remain, synergistic adjusting various microstructures and photo/electrochemical parameters of graphitic carbon nitride (g-C3 N4 ) in photocatalytic hydrogen evolution reaction (HER) are the keys to alleviating the energy crisis and environmental pollution. In this work, a novel nitrogen-defective and sulfur-doped g-C3 N4 (S-g-C3 N4 -D) is designed elaborately. Subsequent physical and chemical characterization proved that the developed S-g-C3 N4 -D not only displays well-defined 2D lamellar morphology with a large porosity and a high specific surface area but also has an efficient light utilization and carriers-separation and transfer. Moreover, the calculated optimal Gibbs free energy of adsorbed hydrogen (ΔGH* ) for S-g-C3 N4 -D at the S active sites is close to zero (≈0.24 eV) on the basis of first-principle density functional theory (DFT). Accordingly, the developed S-g-C3 N4 -D catalyst shows a high H2 evolution rate of 5651.5 µmol g-1  h-1 . Both DFT calculations and experimental results reveal that a memorable defective g-C3 N4 /S-doped g-C3 N4 step-scheme heterojunction is constructed between S-doped domains and N-defective domains in the structural configuration of S-g-C3 N4 -D. This work exhibits a significant guidance for the design and fabrication of high-efficiency photocatalysts.

7.
Chemistry ; 29(64): e202301967, 2023 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-37608518

RESUMO

Pyroelectric materials in the field of photoelectrochemical (PEC) water splitting still face the problems of difficult low spontaneous polarization intensity and excessive carrier recombination. Based on the above problems, we altered the interaction between S-Nb-S in the [NbO]6-x -xS structure, and the constructed [NbO]6-x -xS structure achieved the regulation of charge density change and spontaneous polarization. The results show that under the stimulation of light and temperature fluctuations, the current density of the NS-4 photoanode is as high as 0.574 mA/cm2 at 1.23 VRHE , which is about 1.59 times higher than the pure NaNbO3 current density value, and the NS -4 photoanode achieves IPCE value of 16.08 %. The first-principles density-functional theory calculations (DFT) reveal the principle of the [NbO]6-x -xS structure for the suppression function of the carrier recombination and the improvement function of the pyroelectric effect. The analysis shows that the S-doping leads to the weakening of S-Nb-S interactions in the [NbO]6-x -xS structure, which improves the pyroelectric effect and suppresses the photo/pyro-generated carrier recombination, and effectively enhances the performance of the pyro-photo-electric synergistic water splitting system. This work promotes the development of pyroelectric materials in the field of photoelectrochemical water splitting.

8.
Chemistry ; 29(11): e202203115, 2023 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-36333273

RESUMO

Peri-thiaxanthenothiaxanthene, an S-doped analog of peri-xanthenoxanthene, is used as a polycyclic aromatic hydrocarbon (PAH) scaffold to tune the molecular semiconductor properties by editing the oxidation state of the S-atoms. Chemical oxidation of peri-thiaxanthenothiaxanthene with H2 O2 led to the relevant sulfoxide and sulfone congeners, whereas electrooxidation gave access to sulfonium-type derivatives forming crystalline mixed valence (MV) complexes. These complexes depicted peculiar molecular and solid-state arrangements with face-to-face π-π stacking organization. Photophysical studies showed a widening of the optical bandgap upon progressive oxidation of the S-atoms, with the bis-sulfone derivative displaying the largest value (E00 =2.99 eV). While peri-thiaxanthenothiaxanthene showed reversible oxidation properties, the sulfoxide and sulfone derivatives mainly showed reductive events, corroborating their n-type properties. Electric measurements of single crystals of the MV complexes exhibited a semiconducting behavior with a remarkably high conductivity at room temperature (10-1 -10-2  S cm-1 and 10-2 -10-3  S cm-1 for the O and S derivatives, respectively), one of the highest reported so far. Finally, the electroluminescence properties of the complexes were tested in light-emitting electrochemical cells (LECs), obtaining the first S-doped mid-emitting PAH-based LECs.

9.
Angew Chem Int Ed Engl ; 62(25): e202303117, 2023 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-37078760

RESUMO

Bismuth-based materials have been recognized as promising catalysts for the electrocatalytic CO2 reduction reaction (ECO2 RR). However, they show poor selectivity due to competing hydrogen evolution reaction (HER). In this study, we have developed an edge defect modulation strategy for Bi by coordinating the edge defects of bismuth (Bi) with sulfur, to promote ECO2 RR selectivity and inhibit the competing HER. The prepared catalysts demonstrate excellent product selectivity, with a high HCOO- Faraday efficiency of ≈95 % and an HCOO- partial current of ≈250 mA cm-2 under alkaline electrolytes. Density function theory calculations reveal that sulfur tends to bind to the Bi edge defects, reducing the coordination-unsaturated Bi sites (*H adsorption sites), and regulating the charge states of neighboring Bi sites to improve *OCHO adsorption. This work deepens our understanding of ECO2 RR mechanism on bismuth-based catalysts, guiding for the design of advanced ECO2 RR catalysts.


Assuntos
Bismuto , Dióxido de Carbono , Formiatos , Enxofre , Hidrogênio
10.
Nanotechnology ; 33(6)2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34706360

RESUMO

Developing nonprecious-metal based catalysts with highly active and stable performance for hydrogen evolution reaction (HER) in neutral media is crucial points for realizing low-carbon economy because their practical use typically suffers from the slow kinetics. Herein, we developed S-doped MoO3nanosheets toward neutral HER, fabricated by a versatile solvothermal and subsequently sulfuration processes. The obtained catalyst exhibits a small overpotential of 106 mV to reach 10 mA cm-2in 1.0 M phosphate buffered saline, overwhelming most of recently reported catalysts. Meantime, it shows no notable deactivation after more than 60 h continuous electrolysis and 50 000 cycling tests. More importantly, the catalyst also can be applied in buffered seawater for electrocatalyzing HER, requiring 262 mV at 10 mA cm-2and maintaining over 60 h. These findings open a new route for designing MoO3-based catalysts for neutral hydrogen production.

11.
Nanotechnology ; 2020 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-32764199

RESUMO

Developing cost-effective, highly active, and stable electrocatalysts for boosting electrochemical hydrogen evolution reaction (HER) in alkaline media is playing a critical role to meet hydrogen industry in the future. Herein, an efficient HER electrocatalyst based on flowerlike S-doped Ni2P mesoporous nanosheets supported on nickel foam (S-Ni2P NSs/NF) was developed through an effective approach. The obtained S-Ni2P NSs/NF catalyst required low overpotential of only 87.5 mV and 179.1 mV to reach current density of 10 and 50 mA cm-2, respectively. Moreover, a small Tafel slope of 62.1 mV dec-1 for S-Ni2P NSs/NF demonstrated that HER process occurred with very fast kinetics. Besides high HER activity, the synthesized S-Ni2P NSs/NF catalyst exhibited superior stability and long-term durability toward HER, which had ability to operate over 30 h without degradation in catalytic performance. The unique flower-like nanosheets structure with excellent mesoporous characteristics of S-Ni2P NSs/NF resulted in maximizing electrochemical active surface area for providing a large number of electrocatalytic active sites. In addition, S doping effect could modulate electronic structure of Ni species in Ni2P, leading to accelerating rate adsorption of reaction intermediates on the surface of catalysts toward improving HER kinetics. The results not only demonstrate S-Ni2P NSs/NF as active catalyst for HER, but also offer effective strategy for improving catalytic activity of earth-abundant transition metal-based HER catalysts.

12.
Int J Biol Macromol ; 278(Pt 2): 134765, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39153671

RESUMO

Industrial lignin is a waste product of the paper industry, which contains a large amount of oxygen group structure, and can be used to treat industrial wastewater containing Cr(VI). However, lignin has very low reactivity, so how to enhance its adsorption performance is a major challenge at present. In this study, a two-stage hydrothermal and activation strategy was used to activate the lignin activity and doping S element to prepare high-performance S-doped lignin-based polyporous carbon (S-LPC). The results show that the surface of S-LPC is rich in S and O groups and has a well-developed pore structure, which is very beneficial to Cr(VI) uptake -reduction and mass transfer on the material. In the wastewater, the utmost adsorption potential of Cr(VI) by S-LPC achieved 882.83 mg/g. After 7 cycles of regeneration, the adsorption of S-LPC decreased by only approximately 18 %. Ion competition experiments showed that S-LPC has excellent specificity for Cr(VI) adsorption. In factory wastewater, the adsorption performance of S-LPC for Cr(VI) remained above 95 %, which shows the excellent performance of S-LPC in practical applications. The results are of great significance for green chemical utilization of waste lignin, treatment of industrial wastewater and sustainable development.


Assuntos
Carbono , Cromo , Resíduos Industriais , Lignina , Águas Residuárias , Poluentes Químicos da Água , Purificação da Água , Lignina/química , Cromo/química , Cromo/isolamento & purificação , Adsorção , Águas Residuárias/química , Porosidade , Carbono/química , Purificação da Água/métodos , Poluentes Químicos da Água/química
13.
Artigo em Inglês | MEDLINE | ID: mdl-39315720

RESUMO

Red phosphorus (RP) with a high theoretical specific capacity (2596 mA h g-1) and a moderate lithiation potential (∼0.7 V vs Li+/Li) holds promise as an anode material for lithium-ion batteries (LIBs), which still confronts discernible challenges, including low electrical conductivity, substantial volumetric expansion of 300%, and the shuttle effect induced by soluble lithium polyphosphide (LixPPs). Here, S-NRP@Ti3C2Tx composites were in situ prepared through a phosphorus-amine-based method, wherein S-doped red phosphorus nanoparticles (S-NRP) grew and anchored on the crumpled Ti3C2Tx nanosheets via Ti-O-P bonds, constructing a three-dimensional porous structure which provides fast channels for ion and electron transport and effectively buffers the volume expansion of RP. Interestingly, based on the results of adsorption experiments of polyphosphate and DFT calculation, Ti3C2Tx with abundant oxygen functional groups delivers a strong chemical adsorption effect on LixPPs, thus suppressing the shuttle effect and reducing irreversible capacity loss. Furthermore, S-doping improved the conductivity of red phosphorus nanoparticles, facilitating Li-P redox kinetics. Hence, the S-NRP@Ti3C2Tx anode demonstrates outstanding rate performance (1824 and 1090 mA h g-1 at 0.2 and 4.0 A g-1, respectively) and superior cycling performance (1401 mAh g-1 after 500 cycles at 2.0 A g-1).

14.
Environ Sci Pollut Res Int ; 31(1): 740-756, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38019407

RESUMO

In the present studies, the synthesis of pure ZnO nanoparticles and Mg and S-doped ZnO particles were carried out using a non-aqueous sol-gel method. The synthesized nanoparticles (NPs) are characterized using XRD, FESEM, EDX, FTIR, UV-Vis-DRS, XPS, PL, and BET surface area analysis. X-ray diffraction (XRD) techniques were used to examine the crystallization of ZnO, Mg-ZnO, and S-ZnO samples. The Mg-ZnO and S-ZnO samples exhibit significant c-axis compression and smaller crystallite sizes as compared to undoped ZnO. The optical band gap of Mg-ZnO and S-ZnO NPs were found to be 2.93 eV and 2.32 eV, respectively, which are lower than that of ZnO NPs (3.05 eV). The S-doped ZnO resulted in the homogenous distribution of sulfur ions in the ZnO lattice crystal. XPS analysis revealed that the doped S element was mostly S4+ and S6+. A systematic evaluation has been conducted to assess the influence of several operational parameters, including doped/undoped stoichiometry, solution pH, catalyst dosage, and radical trapping experiment, on the photocatalytic degradation of Rhodamine 6G (Rh 6G) dye. Furthermore, we investigated the photocatalytic degradation activity of ZnO, Mg-ZnO, and S-ZnO samples with aquoues solution of 5 ppm Rhodamine 6G (Rh 6G) at room temperature. Results indicated that pure ZnO nanoparticles have the highest photocatalytic degradation rate constant (0.00344 min-1), compared to the samples Mg-ZnO (0.00104 min-1) and S-ZnO (0.00108 min-1) with Rh 6G dye in presence of visible light emitting diode (Vis-LED) source at room temperature. The enhanced visible light photocatalytic activities of pure ZnO NPs were attributed to their superior surface properties (18.30 m2/g) and effective electron-hole separation.


Assuntos
Nanopartículas , Óxido de Zinco , Óxido de Zinco/química , Análise Custo-Benefício , Luz
15.
Environ Sci Pollut Res Int ; 31(6): 8538-8551, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38180663

RESUMO

In this study, the anaerobic sludge withdrawn from thickener in a sewage treatment plant served as the precursor for sludge-based biochar fabrication, which was further modified via sulfur (S) heteroatom doping (i.e., S-BC). The S atom doping resulted in the adjustment of the physicochemical properties towards the carbon material, endowment of abundant functional groups on biochar surface, and increasing the binding sites between biochar and Cr(VI). Compared to the primary biochar (i.e., biochar without heteroatomic doping, named BC), S-BC exhibited a rough surface and possessed remarkable advantages in ash content, specific surface area, and pore volume. The existence of graphene carbon crystal structure for S-BC was confirmed through S-BC by XRD and FTIR analysis. The studies of adsorption kinetics and isotherms showed that pseudo-second-order kinetics and the Langmuir model more fitted the Cr(VI) removal behavior in the presence of S-BC. Therefore, the chemisorption and monolayer adsorption were the primary mechanisms involved in the Cr(VI) removal process. Additionally, XPS analysis results illustrated the aqueous Cr(VI) was efficiently eliminated through the synergistic effect of chemisorption and reduction to Cr(III) in the presence of S-BC. Moreover, S-BC could still achieve the Cr(VI) eliminating efficiency of 85.31% undergoing five cycles with unchanged functional group and crystal structure via FTIR and XRD analysis. Thus, the results of this study may shed light on a new approach for simultaneous economical sludge disposal and the sustainable remediation of the Cr(VI)-contaminated wastewater.


Assuntos
Esgotos , Poluentes Químicos da Água , Adsorção , Poluentes Químicos da Água/análise , Carvão Vegetal/química , Carbono , Cromo/química , Enxofre , Cinética
16.
Chem Asian J ; 18(16): e202300449, 2023 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-37382427

RESUMO

Hard carbon, as the most promising commercial anode materials of sodium-ion batteries (SIBs), has suffered from the coupling limitations on initial Coulombic efficiency (ICE), capacity, and rate capability. Herein, to break such coupling limitations, sulfur-rich nitrogen-doped carbon nanomaterials (S-NC) were synthesized by a synergistic modification strategy, including structure/morphology regulation and dual heteroatom doping. The small specific surface area of S-NC is beneficial for inhibiting excessive growth of solid electrolyte interphase (SEI) film and irreversible interfacial reaction. The covalent S can serve as active electrochemical sites by Faradaic reactions and provide extra capacity. Benefit by N, S co-doping, S-NC shows large interlayer spacing, high defects, good electronic conductivity, strong ion adsorption performance, and fast Na+ ion transport, which combined with a more significant pore volume result in speedier reaction kinetics. Hence, S-NC possesses a high reversible specific capacity of 464.7 mAh g-1 at 0.1 A g-1 with a high ICE of 50.7%, excellent rate capability (209.8 mAh g-1 at 10.0 A g-1 ), and superb long-cycle capability delivering a capacity of 229.0 mAh g-1 (85% retention) after 1800 cycles at 5.0 A g-1 .

17.
ACS Appl Mater Interfaces ; 15(33): 40088-40099, 2023 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-37556855

RESUMO

It is vital to recycle precious metals effectively such as silver from waste sources because of limited natural reserves. Herein, passion fruit (Passiflora edulis Sims) shell-derived S-doped porous carbons (SPCs) were newly synthesized by hydrothermal carbonization and following with activation by KOH/(NH4)2SO4, and the adsorption of Ag+ on SPC under acidic solutions was investigated. It was found that the activator of (NH4)2SO4 can not only introduce the doping of S elements but also increase the proportion of mesopores in the as-prepared SPC. As the active site, the increasing S doping can improve the adsorption of Ag+ on SPC. The kinetic data of Ag+ adsorption by SPC was consistent with the pseudo-second-order kinetic model. The Langmuir isothermal model was used to well fit the Ag+ adsorption isotherms of SPC, and the maximum adsorption capacity of the optimized SPC-3 for Ag+ is up to 115 mg/g in 0.5 mol/L HNO3 solution. SPC-3 showed good selectivity toward Ag+ over diverse competing cations, which is mainly attributed to the strong bonding between Ag+ ions and the sulfur-containing functional groups on the surface of SPC-3 resulting in the formation of Ag2S nanoparticles. The adsorbed Ag could be recovered as an elemental form by a simple calcination. This study provides a new insight into the design of an environmentally friendly and efficient adsorbent for the selective recovery of silver from acidic aqueous media.

18.
J Colloid Interface Sci ; 645: 371-379, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37156145

RESUMO

The sluggish extracellular electron transfer has been known as one of the bottlenecks to limit the power density of microbial fuel cells (MFCs). Herein, molybdenum oxides (MoOx) are doped with various types of non-metal atoms (N, P, and S) by electrostatic adsorption, followed by high-temperature carbonization. The as-prepared material is further used as MFC anode. Results indicate that all different elements-doped anodes can accelerate the electron transfer rate, and the great enhancement mechanism is attributed to synergistic effect of dopped non-metal atoms and the unique MoOx nanostructure, which offers high proximity and a large reaction surface area to promote microbe colonization. This not only enables efficient direct electron transfer but also enriches the flavin-like mediators for fast extracellular electron transfer. This work renders new insights into doping non-metal atoms onto metal oxides toward the enhancement of electrode kinetics at the anode of MFC.


Assuntos
Fontes de Energia Bioelétrica , Molibdênio , Óxidos , Transporte de Elétrons , Eletrodos
19.
J Colloid Interface Sci ; 623: 146-154, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35576646

RESUMO

Iron-nitrogen-carbon (FeNC) catalysts derived from zeolitic-imidazolate frameworks (ZIFs) are worldwide accepted to be the most promising candidates for the oxygen reduction reaction (ORR), but the insufficient stability, the low FeNx exposure and poor density restrict their ORR activity. Here, we demonstrate a strategy to synthesize FeNx sites embedded in a micro/mesoporous N, S co-doped graphitic carbon (FeNC/MUS) by tuning the ligand linkers via the addition of 2-undecylimidazole as a co-ligand in ZIF precursors, and optimizing the electronic structure of Fe center by an in-situ addition of thiourea molecules as sulfur (S) source. 2-undecylimidazole offered an open porous structure to incorporate more FeNx, while the S-doping increased the density of FeNx. Besides, 2-undeclyimidazole cooperatively with S-doping caused favorable changes into the catalyst structure, particularly improved the exposure and density of FeNx sites and doubled the Brunauer-Emmetter-Teller surface area to 1132 m2 g-1 contrasted to the pristine FeNC/M (544 m2 g-1). FeNC/MUS displayed an accelerated ORR activity with a higher half-wave potential of 0.86 V (vs. reversible hydrogen electrode (RHE)) than that of Pt/C (0.84 V) in addition of a longer durability with a 11 % of activity decay after 30000 s in alkaline media. This work offers a new insight to design optimal ZIFs precursor and a facile electron withdrawing S-doping strategy for efficient electrocatalysis.

20.
Nanomaterials (Basel) ; 12(9)2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35564204

RESUMO

Iron-based nanomaterials (NMs) are increasingly used to promote extracellular electron transfer (EET) for energy production in bioelectrochemical systems (BESs). However, the composition and roles of planktonic bacteria in the solution regulated by iron-based NMs have rarely been taken into account. Herein, the changes of the microbial community in the solution by S-doped NiFe2O4 anodes have been demonstrated and used for constructing electroactive consortia on normal carbon cloth anodes, which could achieve the same level of electricity generation as NMs-mediated biofilm, as indicated by the significantly high voltage response (0.64 V) and power density (3.5 W m-2), whereas with different microbial diversity and connections. Network analysis showed that the introduction of iron-based NMs made Geobacter positively interact with f_Rhodocyclaceae, improving the competitiveness of the consortium (Geobacter and f_Rhodocyclaceae). Additionally, planktonic bacteria regulated by S-doped anode alone cannot hinder the stimulation of Geobacter by electricity and acetate, while the assistance of lining biofilm enhanced the cooperation of sulfur-oxidizing bacteria (SOB) and fermentative bacteria (FB), thus promoting the electroactivity of microbial consortia. This study reveals the effect of S-doped NiFe2O4 NMs on the network of microbial communities in MFCs and highlights the importance of globality of microbial community, which provides a feasible solution for the safer and more economical environmental applications of NMs.

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