Site Of Electron Transfer Research Articles

A novel multifunctional sensor based on rGO-CuxONW-AgNW/PDMS composites for detecting gas and pressure

Flexible electronic skin (e-skin) for mobile health applications urgently requires wearable pressure-gas sensors, which can be used for body motion detection and identification of environmental gas targets. However, applying pressure-gas sensors to e-skin has always faced challenges of high sensitivity, wide detection range, and high stability. Herein, a novel multifunctional pressure-gas sensor was proposed that 2D reduced graphene oxide (rGO) with 1D copper nanowires (CuNWs) and silver nanowires (AgNWs) form 3D porous composite aerogels by self-assembly and in situ oxidation CuNWs convert to CuxO nanowires (CuxONWs), which ensures efficient electron transfer and sufficient gas adsorption sites. Furthermore, the polydimethylsiloxane (PDMS) layer dramatically improved the electro-mechanical properties of the sensing elastomer. The rGO-CuxONW-AgNW/PDMS (GCOAP) sensing elastomer realizes bi-directional resistive response of pressure (falling) and gas (rising), and is capable of fast response (66 ms) to large pressures (1600 kPa) with high sensitivity (1.405 kPa−1) and specific identification of hazardous NH3 gas at room temperature.

Mechanochemical synthesis of biochar encapsulated FeMn nanoparticles with strong metal–carbon interactions for efficient degradation of tetracycline via activating peroxymonosulfate

Transition metal and carbon nanomaterials are well-known for their peroxymonosulfate (PMS) activation capabilities. However, metal-based materials often suffer from ion leakage and poor reusability, while carbon-based materials have limited catalytic efficiency. To overcome these challenges and leverage the strengths of both, we introduce carbon-coated Fe/Mn composites (FeMn@BC), that establish strong interactions between metal components and the carbon substrate. FeMn@BC exhibited exceptional selectivity for 1O2 generation via PMS activation. In practical applications, FeMn@BC efficiently degraded tetracycline by activating PMS, achieving 99.1% removal in just 30 min. Importantly, FeMn@BC demonstrated remarkable stability, especially under visible light exposure. XPS analyses revealed strong interactions between FeMn components and the biochar shell, enhancing the electron transfer capacity of FeMn@BC through Fe(III)/Fe(II) and Mn(III)/Mn(II) redox pairs. In-situ attenuated total reflection Fourier-transform infrared (ATR-FTIR) analysis highlighted abundant hydroxyl groups in FeMn@BC as crucial active sites for electron transfer. Quenching experiments and electron paramagnetic resonance (EPR) measurements unveiled that FeMn@BC catalyzed 1O2 generation primarily through the disproportionation of O2− and energy transfer from oxygen vacancy to O2. Our work demonstrates the possibility of simple ball milling of biomass in the presence of iron salts for iron-catalyzed mechanochemical synthesis of biochar-based catalysts. This study not only presents a novel strategy for large-scale biochar-encapsulated transition metal catalyst synthesis but also explores the potential use of agricultural waste for value-added applications.

Characterization of tryptophan oxidation affecting D1 degradation by FtsH in the photosystem II quality control of chloroplasts.

Photosynthesis is one of the most important reactions for sustaining our environment. Photosystem II (PSII) is the initial site of photosynthetic electron transfer by water oxidation. Light in excess, however, causes the simultaneous production of reactive oxygen species (ROS), leading to photo-oxidative damage in PSII. To maintain photosynthetic activity, the PSII reaction center protein D1, which is the primary target of unavoidable photo-oxidative damage, is efficiently degraded by FtsH protease. In PSII subunits, photo-oxidative modifications of several amino acids such as Trp have been indeed documented, whereas the linkage between such modifications and D1 degradation remains elusive. Here, we show that an oxidative post-translational modification of Trp residue at the N-terminal tail of D1 is correlated with D1 degradation by FtsH during high-light stress. We revealed that Arabidopsis mutant lacking FtsH2 had increased levels of oxidative Trp residues in D1, among which an N-terminal Trp-14 was distinctively localized in the stromal side. Further characterization of Trp-14 using chloroplast transformation in Chlamydomonas indicated that substitution of D1 Trp-14 to Phe, mimicking Trp oxidation enhanced FtsH-mediated D1 degradation under high light, although the substitution did not affect protein stability and PSII activity. Molecular dynamics simulation of PSII implies that both Trp-14 oxidation and Phe substitution cause fluctuation of D1 N-terminal tail. Furthermore, Trp-14 to Phe modification appeared to have an additive effect in the interaction between FtsH and PSII core in vivo. Together, our results suggest that the Trp oxidation at its N-terminus of D1 may be one of the key oxidations in the PSII repair, leading to processive degradation by FtsH.

Characterization of tryptophan oxidation affecting D1 degradation by FtsH in the photosystem II quality control of chloroplasts

Photosynthesis is one of the most important reactions for sustaining our environment. Photosystem II (PSII) is the initial site of photosynthetic electron transfer by water oxidation. Light in excess, however, causes the simultaneous production of reactive oxygen species (ROS), leading to photo-oxidative damage in PSII. To maintain photosynthetic activity, the PSII reaction center protein D1, which is the primary target of unavoidable photo-oxidative damage, is efficiently degraded by FtsH protease. In PSII subunits, photo-oxidative modifications of several amino acids such as Trp have been indeed documented, whereas the linkage between such modifications and D1 degradation remains elusive. Here, we show that an oxidative post-translational modification of Trp residue at the N-terminal tail of D1 is correlated with D1 degradation by FtsH during high-light stress. We revealed that Arabidopsis mutant lacking FtsH2 had increased levels of oxidative Trp residues in D1, among which an N-terminal Trp-14 was distinctively localized in the stromal side. Further characterization of Trp-14 using chloroplast transformation in Chlamydomonas indicated that substitution of D1 Trp-14 to Phe, mimicking Trp oxidation enhanced FtsH-mediated D1 degradation under high light, although the substitution did not affect protein stability and PSII activity. Molecular dynamics simulation of PSII implies that both Trp-14 oxidation and Phe substitution cause fluctuation of D1 N-terminal tail. Furthermore, Trp-14 to Phe modification appeared to have an additive effect in the interaction between FtsH and PSII core in vivo. Together, our results suggest that the Trp oxidation at its N-terminus of D1 may be one of the key oxidations in the PSII repair, leading to processive degradation by FtsH.

Fullerene Fragment Restructuring: How Spatial Proximity Shapes Defect-Rich Carbon Electrocatalysts.

Fullerene transformation emerges as a powerful route to construct defect-rich carbon electrocatalysts, but the carbon bond breakage and reformation that determine the defect states remain poorly understood. Here, we explicitly reveal that the spatial proximity of disintegrated fullerene imposes a crucial impact on the bond reformation and electrocatalytic properties. A counterintuitive hard-template strategy is adopted to enable the space-tuned fullerene restructuring by calcining impregnated C60 not only before but also after the removal of rigid silica spheres (∼300 nm). When confined in the SiO2 nanovoids, the adjacent C60 fragments form sp3 bonding with adverse electron transfer and active site exposure. In contrast, the unrestricted fragments without SiO2 confinement reconnect at the edges to form sp2-hybridized nanosheets while retaining high-density intrinsic defects. The optimized catalyst exhibits robust alkaline oxygen reduction performance with a half-wave potential of 0.82 V via the 4e- pathway. Copper poisoning affirms the intrinsic defects as the authentic active sites. Density functional theory calculations further substantiate that pentagons in the basal plane lead to localized structural distortion and thus exhibit significantly reduced energy barriers for the first O2 dissociation step. Such space-regulated fullerene restructuring is also verified by heating C60 crystals confined in gallium liquid and a quartz tube.

Visible light-driven LaFeO3-biochar composites for removal of sulfamethoxazole by enhanced electron transfer coupled with peroxymonosulfate

In this study, we prepared a novel biochar and LaFeO3-bonded nanosphere composite (LFBC) using a co-precipitation-pyrolysis method for the degradation of sulfamethoxazole (SMX). Under visible light conditions, LFBC-activated peroxymonosulfate (PMS) completely removed SMX within 25 min with rate constants 23 and 59 times higher than those of LaFeO3 and biochar, respectively. Both free radical and non-free radical pathways participated in the SMX degradation process, with the non-free radical pathway playing a primary role. It is noteworthy that the interaction between LaFeO3 and Biochar facilitated electron transfer and active sites, promoted the redox cycle of Fe3+/Fe2+, and greatly enhanced the catalytic performance of the composites. Degradation pathway and toxicity evaluation of pollutant removal processes in LFBC/PMS/vis systems based on intermediate identification and Fukui function calculations. This work proved the excellent synergistic performance of LFBC in light utilization and PMS activation, providing a potential utilization for efficient treatment of antibiotic wastewater and antibiotic-resistant bacteria.

In-situ engineering of 3D porous Co nanoparticles incorporated in B/N Co-doped carbon nanotube/nanofiber networks as integrated cathode materials for Zn-air batteries

Rational design and construction of low-cost and highly efficient bifunctional catalysts toward oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is crucial for the commercialization of the rechargeable Zn-air batteries (ZABs). Herein, a 3D self-standing bifunctional catalytic electrode has been successfully achieved by in-situ confinement of Co nanoparticles into B/N co-doped carbon nanotube/nanofiber well-integrated networks (Co-B/N-CNTs@CFs). The purpose of designing such a 3D network structure is to optimize the electronic structure of the active sites for high electrocatalytic activity, ensure continuous and fast electron and charge transfer for high utilization of active sites, and avoid the abscission and aggregation of nanocatalysts for high electrocatalytic stability, which is confirmed by a series of experimental, characterization, and theoretical studies. As a result, the Co-B/N-CNTs@CFs as integrated cathode materials deliver efficient and stable OER/ORR performance with a ΔE of 0.59 V, largely outperforming the benchmark Pt/C-RuO2 electrode (0.71 V), and hence leading to appealing applications in both the assembled aqueous and flexible solid-state ZABs. This study forges a new path for the production of integrated cathode while enhancing their superiority, allowing for the construction of energy storage devices.

Photo-switchable In(III)-to-In(I) site on oxygen vacancy-laden BiOCl surface for selective degradation of monocyclic aromatic compounds

Enrichment of OVs on oxide semiconductors is an effective strategy to promote their photocatalytic performances but limited by the maximum concentration allowed by lattice thermodynamics. Herein, we report that an In(I) doping strategy, realized by an UV light-induced reduction of a sluggish In(III) precursor, can promote OVs-laden BiOCl by up to 6.5 times for the visible-light sodium pentachlorophenate (PCPNa) degradation. The photocatalysis mechanism study highlighted the In(I) site as an electron transfer site could reduce PCPNa directly, related to the In(I) induced more negative conduction band and faster transfer of electron. Moreover, several monocyclic aromatic organic compounds (AOC) exhibited degradation selectivity over In(I) doped OVs-laden BiOCl (BOVs-In) by an electron reduction path, PCPNa with the lowest negative charge density on the benzene ring has been degraded fastest. Differently, the doped In(I) in BOVs-In mainly triggered the multiring Rhodamine B degradation by promoting the O2− generation not the directly electron reduction path. The electron transfer ability, band structure, and the free energy of O2 activation over BOVs-In were confirmed by TPV spectra, EPR spectra and DFT calculation. This study illustrates an In(I) doping strategy to couple with OVs engineering for champion photoactivity of BiOCl for AOC degradation under visible light irradiation.

Functional distinction of different components in SmCeMn/Ti catalytic system for NH3-SCR

Active components play different roles in improving catalytic performance due to their different physicochemical properties. In multicomponent catalysts, different components provide the possibility of multiple structures and catalytic feasibility, but the role played by specific components in improving performance becomes confusing. This work synthesized a series of SmCeMn/Ti catalysts with different metal components exposed on the outer surface to study their catalytic roles for NH3-SCR. For the contribution of different components to the catalytic activity, Mn contributes more B-acid sites and Mn4+, facilitating NO conversion. Ce generates a large amount of Mn4+ through a strong redox reaction with Mn3+ and generates abundant oxygen vacancies during the reaction process due to its strong oxygen storage-release capacity, and Sm acts as a sacrifice site for electron transfer with Mn to improve the sulfur resistance. Further investigations show that the three components have different adsorption behaviors for reactant gas and thus provide various catalytic feasibility. This work establishes a specific catalytic model for Sm, Ce, and Mn species, respectively, which provides experimental guidance to improve activity and sulfur resistance by active component control.

Three structures of PSI-LHCI from Chlamydomonas reinhardtii suggest a resting state re-activated by ferredoxin

Photosystem I (PSI) from the green alga Chlamydomonas reinhardtii, with various numbers of membrane bound antenna complexes (LHCI), has been described in great detail. In contrast, structural characterization of soluble binding partners is less advanced. Here, we used X-ray crystallography and single particle cryo-EM to investigate three structures of the PSI-LHCI supercomplex from Chlamydomonas reinhardtii. An X-ray structure demonstrates the absence of six chlorophylls from the luminal side of the LHCI belts, suggesting these pigments were either physically absent or less stably associated with the complex, potentially influencing excitation transfer significantly. CryoEM revealed extra densities on luminal and stromal sides of the supercomplex, situated in the vicinity of the electron transfer sites. These densities disappeared after the binding of oxidized ferredoxin to PSI-LHCI. Based on these structures, we propose the existence of a PSI-LHCI resting state with a reduced active chlorophyll content, electron donors docked in waiting positions and regulatory binding partners positioned at the electron acceptor site. The resting state PSI-LHCI supercomplex would be recruited to its active form by the availability of oxidized ferredoxin.

Reason for the increased electroactivity of extracellular polymeric substances with electrical stimulation: Structural change of α-helix peptide of protein

Electroactivity is an important parameter to assess the ability of the extracellular polymeric substance (EPS) of microorganisms to participate in extracellular respiration. Many reports have found that the electroactivity of microbial sludge could be enhanced with electrical stimulation, but the reason remains unclear. The results of this study showed that the current generation of the three microbial electrolysis cells increased by 1.27–1.76 times during 49 days of electrical stimulation, but the typical electroactive microorganisms were not enriched. Meanwhile, the capacitance and conductivity of EPS of sludge after the electrical stimulation increased by 1.32–1.83 times and 1.27–1.32 times, respectively. In-situ FTIR analysis indicated that the electrical stimulation could lead to the polarization of amide groups in the protein, likely affecting the protein structure related to the electroactivity. Accordingly, the dipole moment of the α-helix peptide of protein of sludge increased from 220 D to 280 D after the electrical stimulation, which was conducive to electron transfer in the α-helix peptide. Moreover, the vertical ionization potential and ELUMO-EHOMO energy gap of the C-terminal in the α-helix peptide decreased from 4.43 eV to 4.10 eV and 0.41 eV to 0.24 eV, respectively, which indicated that the α-helix was easier to serve as the electron transfer site of electron hopping. These results meant that the enhancement of the dipole moment of the α-helix peptide unchoked the electron transfer chain of the protein, which was the main reason for the increased electroactivity of EPS protein.

Amorphous Copper-Based Nanoparticles with Clusterization-Triggered Phosphorescence for Ultrasensing 2,4,6-Trinitrotoluene.

Amorphous metal-based nanostructures have attracted great attention recently due to their facilitative electron transfer and abundant reactive sites, whereas it remains enigmatic whether the amorphous copper-based nanoparticles (CuNPs) could be achieved. Here, for synthesizing amorphous CuNPs, glutathione was adopted as ligand to inhibit the nucleation and crystallization process via its electrostatic repulsion. By subtly tailoring the solvent polarity, not only the amorphous glutathione functionalized CuNPs (GSH-CuNPs) with phosphorescent performance could be achieved after transferring the non-conjugation of GSH ligand to through-space conjugation, namely clusterization-triggered emission, but also the phosphorescence-off of GSH-CuNPs toward 2,4,6-trinitrotoluene (TNT) could be realized by the photo-induced electron transfer process through hydrogen bond channel, that was established between carboxyl and amino groups of GSH-CuNPs with the nitryl group of TNT. Benefitting from the intrinsic superiorities of the amorphous CuNPs, desired phosphorescence and detection performances of solid-state GSH-CuNPs toward airborne TNT microparticulates have been undoubtedly realized, including high quantum yield (13.22%), excellent specificity in 23 potential interferents, instantaneous response and ultralow detection limit (1.56 pg). The present GSH-CuPCs is expected to stretch amorphous metal-based nanostructures and deepen the insights of amorphous materials for optical detection. This article is protected by copyright. All rights reserved.

Ultralow Fe augmented defect-prone porous carbon for highly efficient supercapacitor

An ultralow Fe-modulated hierarchical porous carbon structure was prepared by defect engineering. Unique porous nature, accessibility, pathway for electron transfer and active site density synergistically contribute to excellent supercapacitor. Defect induced high surface area of Fe-N-doped carbon exhibit 825 F g−1 capacitance at a current density of 0.5 A g−1. An aqueous symmetric system showed capacitance of 87.9 F g−1with a specific energy of 12.66 Wh Kg−1 and specific power of 677 W Kg−1 at 1.0 A g−1. These results ensured that the ultralow Fe doped hierarchical porous carbon structure is a preferable material for energy storage applications.

Altering the Site of Electron Abstraction in Cobalt Corroles via meso-Trifluoromethyl Substituents

A mono-DMSO cobalt meso-CF3 corrole, formulated as (CF3)3CorCo(DMSO), where (CF3)3Cor is the trianion of 5,10,15-tris(trifluoromethyl)corrole, was synthesized and characterized as to its spectral and electrochemical properties in nonaqueous media with a focus on its coordination chemistry and electronic structure. Cyclic voltammetric measurements showed more facile reductions and difficult oxidations compared to the cobalt triarylcorrole possessing p-CF3Ph units at the meso-positions, a result consistent with the enhanced inductive effect of the electron-withdrawing trifluoromethyl substituents linked directly at the meso-carbon atoms of the macrocycle. The effects of DMSO, pyridine, and cyanide anions (CN-) on the electrochemistry and spectral properties of the compound were investigated, and it was found that only two molar equivalents are needed to form the bis-CN adduct, which exhibited two 1-electron oxidations at 0.27 and 0.95 V vs saturated calomel electrode (SCE) in CH2Cl2/0.1 M TBAP. The sites of electron transfer in the first oxidation and reduction were investigated by spectroelectrochemistry and confirmed that the first electron addition affords a Cor3-CoII complex under all solution conditions independent of the initial coordination and/or electronic configuration (i.e., innocent Cor3-CoIII or noninnocent Cor•2-CoII). In contrast, data for the first oxidation suggests that the site of electron abstraction (ligand or metal) depended upon coordination of the neutral and in situ generated complexes under the various solution conditions, leading to a Co(IV)-corrole3- product for both the bis-pyridine and bis-cyanide adducts.

Controllable Synthesis of Carbon Yolk-Shell Microsphere and Application of Metal Compound-Carbon Yolk-Shell as Effective Anode Material for Alkali-Ion Batteries.

Recently, nanostructured carbon materials, such as hollow-, yolk-, and core-shell-configuration, have attracted attention in various fields owing to their unique physical and chemical properties. Among them, yolk-shell structured carbon is considered as a noteworthy material for energy storage due to its fast electron transfer, structural robustness, and plentiful active reaction sites. However, the difficulty of the synthesis for controllable carbon yolk-shell has been raised as a limitation. In this study, novel synthesis strategy of nanostructured carbon yolk-shell microspheres that enable to control morphology and size of the yolk part is proposed for the first time. To apply in the appropriate field, cobalt compounds-carbon yolk-shell composites are applied as the anode of alkali-ion batteries and exhibit superior electrochemical performances to those of core-shell structures owing to their unique structural merits. Co3 O4 -C hollow yolk-shell as a lithium-ion battery anode exhibits a long cycling lifetime (619mA h g-1 for 400 cycles at 2 A g-1 ) and excellent rate capability (286mA h g-1 at 10 A g-1 ). The discharge capacities of CoSe2 -C hollow yolk-shell as sodium- and potassium-ion battery anodes at the 200th cycle are 311mA h g-1 at 0.5 A g-1 and 268mA h g-1 at 0.2 A g-1 , respectively.

Conductive Metal-Organic Framework Microelectrodes Regulated by Conjugated Molecular Wires for Monitoring of Dopamine in the Mouse Brain.

Herein, we demonstrated a strategy to regulate the conductive metal-organic framework (MOF) surface, by the conjugated molecule wires for selective and sensitive determination of dopamine (DA) in the live brain. The MOFs were decorated at the carbon fiber electrode deposited by Au nanoleaves as the upper electric transducer to provide rich electrocatalytic sites for electron transfer of neurochemicals at the electrode surface, leading to greatly enhanced sensitivity for detection of neurochemicals. On the other hand, the conjugated molecular wire, 4-(thiophen-3-ylethynyl)-benzaldehyde (RP1), was synthesized and assembled as an underlying bridge to regulate the electrochemical processes at the MOF-based electrode, specifically decreasing the reaction Gibbs free energy of DA oxidation, thus selectively promoting the heterogeneous electron transfer of DA from the MOF layer to the electrode surface. Owing to the electrocatalytic activity for DA oxidation, the present microsensor exhibited high selectivity for real-time tracking of DA in a good linear relationship in the range of 0.004-0.4 μM with a detection limit of 1 nM. Eventually, this functionalized electrode was successfully applied for in vivo monitoring of DA in mouse brains with Parkinson's disease (PD) model. The results indicated that the levels of DA were obviously decreased in both acute and subacute PD models. Moreover, the level of DA strongly depended on the amount of uric acid (UA), a physiological antioxidant, which rose as the UA amount was lower than 200 mg kg-1 but was downregulated again after treatment by a higher amount of UA.

Experimental and theoretical studies of hexylmeythylimidazolium tetrafluoroborate ionic liquid as cathodic corrosion inhibitor for mild steel

• The imidazolium based ionic liquid HMIM.BF 4 is prepared by following the metathesis reaction. • On mild steel (MS) surfaces, HMIM.BF 4 forms a superhydrophobic film. • The effectiveness of the prepared HMIM.BF 4 is tested using electrochemical experiments. • In HCl, this ionic liquid showed 96 %IE against corrosion according to Langmuir and Temkin isotherms. • Analytical Fukui functions were used to calculate the HMIM.BF 4 's electron transfer site. Ionic liquids (ILs) are principally investigated for their utilization and applications in electrochemistry and their prospective approach to corrosion prevention has attracted a lot of attention. This article explains the synthesis and utility of a room temperature imidazole-based ionic liquid namely 1-hexyl-3-methylimidazolium tetrafluoroborate (HMIM.BF 4 ) as an inhibitor of corrosion on the mild steel surface. The HMIM.BF 4 showed the cathodic type of steel corrosion inhibition with both chemisorption and physisorption nature obeying Langmuir and Temkin adsorption isotherms. At concentrations greater than 100 ppm, the inhibition efficiency of HMIM.BF 4 increases and was found to be 96.27% at 300 ppm. Quantum chemical studies (frontier molecular orbitals and analytical Fukui) have been used to locate the redox-active sites on the inhibitor.

Polydopamine/polypyrrole-modified graphite felt enhances biocompatibility for electroactive bacteria and power density of microbial fuel cell

The interactions between the microbes and the surface of an anode play an important role in capturing the respiratory electrons from bacteria in a microbial fuel cell (MFC). The chemical and electrochemical characteristics of the carbon material affect biofilm growth and direct electron transfer in MFCs. This study examined the electrodeposition of polydopamine (PDA) and polypyrrole (PPY) on graphite felt electrode (GF). The MFC with the modified PDA/PPY-GF reached 920 mW/m2, which was 1.5, 1.17, and 1.18 times higher than those of the GF, PDA-GF, and PPY-GF, respectively. PDA has superior hydrophilicity and adhesive force biofilm formation, while PPY provides electrochemically active sites for microbial electron transfer. Raman spectroscopy, Fourier transform infrared spectroscopy, Brunauer–Emmett–Teller surface area measurements, and contact angle analysis revealed the enhanced physicochemical properties of the carbon electrode. These results show that co-doped PDA/PPY provides a strategy for electroactive biofilm development and improves the bioelectrochemical performance in realistic MFC reactors.

A three-dimensional phenolic-based carbon anode for microbial electrochemical system with customized macroscopic pore structure to promote interior bacteria colonization

Microbial electrochemical system (MES) is an emerging wastewater treatment technology that compensates the energy demands of containments removal by in situ converting the chemical energy of organic pollutants. As the structure for exoelectrogens and the reaction site of extracellular electron transfer (EET), the anode is essential for MES. The future commercial application of MES requires efficiency and large-scale fabrication available anode. In this study, a 3D anode with millimeter-scale pores (3D-MPA) was successfully constructed by sacrificial template method, with low-cost phenolic resin as carbon precursor and polymethyl methacrylate (PMMA) pellets as template. With customized and ordered pore of 1 mm, the 3D-MPAs allowed the microorganisms to colonize inside, improving anodic space utilization efficiency. Different carbonization temperature in tested range from 700 °C to 1000 °C regulated the micrometer-scale convex structures and surface roughness of 3D-MPAs, causing electrochemical performance changes. The 3D-MPA-900 obtained the largest electroactive surface area (102 ± 4.1 cm2) and smallest ohmic resistance (1.8 ± 0.09 Ω). Equipped with MES, 3D-MPA-900 reached the highest power density and current density (2590 ± 25 mW m−2 and 5.20 ± 0.07 A m−2). Among tested 3D-MPA, the excellent performance of 3D-MPA-900 might be attributed by its convex structures with suitable size and surface coverage. The surface roughness of 3D-MPA-900 enhanced the microorganism adherence, which then promoted EET on anode surface. Generally, phenolic-based 3D-MPA made of sacrificial-template method had controllable porous structure, large-scale fabrication availability, high chemical stability and excellent mechanical property, which could be promising for the commercial application of MES.

Cation doping constructed vacancy engineering for designing Sn3Se5@PPy heterostructures toward lithium/sodium-ion batteries

SnSe/SnSe2 heterostructure composites with polypyrrole (PPy) coating layer and selenium (Se) vacancies are prepared by solvothermal and subsequent liquid-phase surface coating methods, and first reported as anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Results indicate that PPy coating can effectively stabilize the structure and improve the electronic conductivity of the material, the heterostructure formed by SnSe and SnSe2 can reduce the reaction barrier and promote charge transfer, and the Se vacancies can provide more active sites for electron transfer and relieve structural strain. In addition, adjusting the molar ratio of SnSe and SnSe2 proves that the as-prepared Sn3Se5@PPy composite has the best rate and excellent cycle performance. Attributed to the difference in alloying between lithium-ion storage and sodium-ion storage, the Sn3Se5@PPy composite deliverers a higher specific capacity as anode for LIBs. It has a higher capacity retention and better rate performance for SIBs. The engineering design of cation doping-induced defects provides a new method for the structural design of high-performance anode materials.