Regulation Of Electron Transfer Research Articles

Hydrophobic Mismatch in the Thylakoid Membrane Regulates Photosynthetic Light Harvesting.

The ability to harvest light effectively in a changing environment is necessary to ensure efficient photosynthesis and crop growth. One mechanism, known as qE, protects photosystem II (PSII) and regulates electron transfer through the harmless dissipation of excess absorbed photons as heat. This process involves reversible clustering of the major light-harvesting complexes of PSII (LHCII) in the thylakoid membrane and relies upon the ΔpH gradient and the allosteric modulator protein PsbS. To date, the exact role of PsbS in the qE mechanism has remained elusive. Here, we show that PsbS induces hydrophobic mismatch in the thylakoid membrane through dynamic rearrangement of lipids around LHCII leading to observed membrane thinning. We found that upon illumination, the thylakoid membrane reversibly shrinks from around 4.3 to 3.2 nm, without PsbS, this response is eliminated. Furthermore, we show that the lipid digalactosyldiacylglycerol (DGDG) is repelled from the LHCII-PsbS complex due to an increase in both the pKa of lumenal residues and in the dipole moment of LHCII, which allows for further conformational change and clustering in the membrane. Our results suggest a mechanistic role for PsbS as a facilitator of a hydrophobic mismatch-mediated phase transition between LHCII-PsbS and its environment. This could act as the driving force to sort LHCII into photoprotective nanodomains in the thylakoid membrane. This work shows an example of the key role of the hydrophobic mismatch process in regulating membrane protein function in plants.

White-Emitting Gold Nanocluster Assembly with Dynamic Color Tuning.

We report that constructed Au nanoclusters (NCs) can afford amazing white emission synergistically dictated by the Au(0)-dominated core-state fluorescence and Au(I)-governed surface-state phosphorescence, with record-high absolute quantum yields of 42.1% and 53.6% in the aqueous solution and powder state, respectively. Moreover, the dynamic color tuning is achieved in a wide warm-to-cold white-light range (with the correlated color temperature varied from 3426 to 24 973 K) by elaborately manipulating the ratio of Au(0) to Au(I) species and thus the electron transfer rate from staple motif to metal kernel. This study not only exemplifies the successful integration of multiple luminescent centers into metal NCs to accomplish efficient white-light emission but also inspires a feasible pathway toward customizing the optical properties of metal NCs by regulating electron transfer kinetics.

Magnetical multi-walled carbon nanotubes with Lewis acid-base imprinted sites for efficient Ni(II) recovery with high selectivity

The recovery of nickel is crucial for both production and environmental protection. In this work, density functional theory (DFT) was utilized to select a highly affine functional monomer, 2-acetamidoacrylic acid (AAA), for the fabrication of a nickel ion-imprinted adsorbent based on magnetic multi-walled carbon nanotubes. The imprinting technique was used to regulate the electron transfer ability of the N and O atoms, which act as “hard” bases in the functional monomer, facilitating strong interaction with Ni(II) featuring “borderline” acid properties. The adsorption capacity of Ni(II) on adsorbents was high up to 75.06 mg/g, reaching equilibrium in about 50 min, and maintaining high recovery efficiency even after six adsorption-desorption cycles. The adsorbent exhibited a high selectivity for Ni(II), with a distribution coefficient of up to 1366. It is noteworthy that the adsorbent's magnetic properties facilitate easy separation under an external magnetic field, reducing the cost of Ni(II) recycling. The use of XPS characterization and DFT analysis provided in-depth understanding of the adsorption and recognition mechanism. Moreover, the recover efficiency of Ni(II) in acidic mining tailwater reaches 97.66 %, demonstrating a high practical value. This research presents an effective strategy to enhance the practicability of ion imprinted adsorbents by regulating electron transfer ability of the adsorption sites through the imprinting technique.

Nanocluster/metal-organic framework nanosheet-based confined ECL enhancement biosensor for the extracellular vesicle detection

Gastric cancer (GC) was one of the most common cancers with high mortality. The detection of GC peritoneal metastasis had important significance. In this work, we have developed the novel electrochemiluminescence (ECL) biosensor to detect microRNA in GC extracellular vesicle (EV). Firstly, in situ growth of Cu nanocluster (Cu NC) on the metal-organic frameworks (MOFs) nanosheet was achieved successfully. Due to the confinement effect, Cu NCs in the porous structure of Zn MOF possessed the high quantum yield and good stability. Meanwhile, Zn MOF provided good electrochemical activity for the ECL reaction. Furthermore, the nanosized MOFs did not only act as sensing platform to load Cu NCs and link biomolecules, but also reduce steric hindrance effect for biomolecular recognition. Additionally, Au NPs/MXene and phospholipid layer were prepared and modified on the electrode, which can regulate electron transfer and improve the target recognition efficiency. The Cu NCs/Zn MOF nanosheet-based ECL sensor was employed to detect miRNA-421 from 1 fM to 1 nM with a detection limit of 0.5 fM. Finally, extracellular vesicles form clinic GC patient ascites were extracted and analyzed. The results showed that the constructed biosensor can be used for the GC peritoneal metastasis diagnosis.

Metal‐free two‐dimensional phosphorene‐based electrocatalyst with covalent P–N heterointerfacial reconstruction for electrolyte‐lean lithium–sulfur batteries

AbstractThe use of lithium–sulfur batteries under high sulfur loading and low electrolyte concentrations is severely restricted by the detrimental shuttling behavior of polysulfides and the sluggish kinetics in redox processes. Two‐dimensional (2D) few layered black phosphorus with fully exposed atoms and high sulfur affinity can be potential lithium–sulfur battery electrocatalysts, which, however, have limitations of restricted catalytic activity and poor electrochemical/chemical stability. To resolve these issues, we developed a multifunctional metal‐free catalyst by covalently bonding few layered black phosphorus nanosheets with nitrogen‐doped carbon‐coated multiwalled carbon nanotubes (denoted c‐FBP‐NC). The experimental characterizations and theoretical calculations show that the formed polarized P–N covalent bonds in c‐FBP‐NC can efficiently regulate electron transfer from NC to FBP and significantly promote the capture and catalysis of lithium polysulfides, thus alleviating the shuttle effect. Meanwhile, the robust 1D‐2D interwoven structure with large surface area and high porosity allows strong physical confinement and fast mass transfer. Impressively, with c‐FBP‐NC as the sulfur host, the battery shows a high areal capacity of 7.69 mAh cm−2 under high sulfur loading of 8.74 mg cm−2 and a low electrolyte/sulfur ratio of 5.7 μL mg−1. Moreover, the assembled pouch cell with sulfur loading of 4 mg cm−2 and an electrolyte/sulfur ratio of 3.5 μL mg−1 shows good rate capability and outstanding cyclability. This work proposes an interfacial and electronic structure engineering strategy for fast and durable sulfur electrochemistry, demonstrating great potential in lithium–sulfur batteries.

Localized surface plasmon resonance-induced bidirectional electron transfer of formic acid adsorption for boosting photocatalytic hydrogen production on Ni/TiO2

Photocatalytichydrogenproduction from formic acid (FA) is a daunting challenge, yet an essential taskforthedevelopmentofhydrogenenergy. In this study, a p-NiO/n-TiO2 heterojunction incorporating 7-nm metallic Ni was fabricated, which demonstrated a remarkable localized surface plasmon resonance (LSPR) effect. Notably, 5 wt% Ni/TiO2 exhibited 1271-fold higher photocatalytic activity (2416 μmol⋅g−1⋅h−1) than TiO2 alone under light radiation at room temperature. The experimental investigations revealed the excitation of distinct components via irradiation by different light sources. Visible light-driven hydrogen production was predominantly influenced by the LSPR-induced hot electrons and holes effects of Ni. Further, FA molecules simultaneously lost and accepted electrons at the Ni0–Ti3+ and Ni0–O2− sites, respectively, generating a bidirectional electron transfer behavior with “valley-shaped” gas-sensitive responses, which was crucial toboosttheactivity. Moreover, the photocatalytic activity was mainly attributed to the heterojunction and defects structure under UV light irradiation, and Ti3+, VOs, and O2− as adsorption sites for FA. Thus, the synergistic interplay among different light sources could effectively boost the photocatalytic hydrogen production performance. Significantly, this research reveals that the LSPR effect of metallic Ni can effectively regulate electron transfer behavior and enhance visible light-driven photocatalytic activity.

Regulating electron transfer and orbital interaction within metalloporphyrin-MOFs for highly sensitive NO2 sensing.

The understanding of electron transfer pathways and orbital interactions between analytes and adsorption sites in gas-sensitive studies, especially at the atomic level, is currently limited. Herein, we have designed eight isoreticular catechol-metalloporphyrin scaffolds, FeTCP-M and InTCP-M (TCP = 5,10,15,20-tetrakis-catechol-porphyrin, M = Fe, Co, Ni and Zn) with adjustable charge transfer schemes in the coordination microenvironment and precise tuning of orbital interactions between analytes and adsorption sites, which can be used as models for exploring the influence of these factors on gas sensing. Our experimental findings indicate that the sensitivity and selectivity can be modulated using the type of metals in the metal-catechol chains (which regulate the electron transfer routes) and the metalloporphyrin rings (which fine-tune the orbital interactions between analytes and adsorption sites). Among the isostructures, InTCP-Co demonstrates the highest response and selectivity to NO2 under visible light irradiation, which could be attributed to the more favorable transfer pathway of charge carriers in the coordination microenvironment under visible light illumination, as well as the better electron spin state compatibility, higher orbital overlap and orbital symmetry matching between the N-2s2pz hybrid orbital of NO2 and the Co-3dz2 orbital of InTCP-Co.

The role of cardiolipin and cytochrome c in mitochondrial metabolism of cancer cells determined by Raman imaging: in vitro study on the brain glioblastoma U-87 MG cell line.

In this paper, we present Raman imaging as a non-invasive approach for studying changes in mitochondrial metabolism caused by cardiolipin-cytochrome c interactions. We investigated the effect of mitochondrial dysregulation on cardiolipin (CL) and cytochrome c (Cyt c) interactions for a brain cancer cell line (U-87 MG). Mitochondrial metabolism was monitored by checking the intensities of the Raman bands at 750 cm-1, 1126 cm-1, 1310 cm-1, 1337 cm-1, 1444 cm-1 and 1584 cm-1. The presented results indicate that under pathological conditions, the content and redox status of Cyt c in mitochondria can be used as a Raman marker to characterize changes in cellular metabolism. This work provides evidence that cardiolipin-cytochrome c interactions are crucial for mitochondrial energy homeostasis by controlling the redox status of Cyt c in the electron transport chain, switching from disabling Cyt c reduction and enabling peroxidase activity. This paper provides experimental support for the hypothesis of how cardiolipin-cytochrome c interactions regulate electron transfer in the respiratory chain, apoptosis and mROS production in mitochondria.

Photosynthetic H2 production: Lessons from the regulation of electron transfer in microalgae

AbstractGreen hydrogen, produced during microalgal photosynthesis, is regarded as one of the most promising sustainable energy sources. It utilizes sunlight and water, which are essentially unlimited, and its combustion results in only water as a waste product. In microalgal hydrogen energy production systems, the sensitivity of hydrogenase to O2 poses a significant challenge, limiting sustained photosynthetic H2 production in microalgae. Additionally, efficient photosynthetic H2 production in anaerobic microalgal cells is hindered by impaired electron source (photosystem II) and electron loss through the Calvin‐Benson cycle, cyclic electron transfer around photosystem I, and O2 photoreduction, which are identified as the other key challenges. Over the past eight decades, considerable progress has been made in addressing these challenges and regulating electron transfer to achieve sustainable and efficient photosynthetic H2 production in microalgae. In this review, we discuss a range of regulatory methods for achieving sustainable and efficient photosynthetic H2 production in microalgae. Emphasizing the significant progress made over the past eight decades, we also address current challenges and propose potential future solutions.

Potential window alignment regulating ion transfer in faradaic junctions for efficient photoelectrocatalysis

In the past decades, a band alignment theory has become a basis for designing different high-performance semiconductor devices, such as photocatalysis, photoelectrocatalysis, photoelectrostorage and third-generation photovoltaics. Recently, a faradaic junction model (coupled electron and ion transfer) has been proposed to explain charge transfer phenomena in these semiconductor heterojunctions. However, the classic band alignment theory cannot explain coupled electron and ion transfer processes because it only regulates electron transfer. Therefore, it is very significant to explore a suitable design concept for regulating coupled electron and ion transfer in order to improve the performance of semiconductor heterojunctions. Herein, we propose a potential window alignment theory for regulating ion transfer and remarkably improving the photoelectrocatalytic performance of a MoS2/Cd-Cu2ZnSnS4 heterojunction photocathode. Moreover, we find that a faradaic potential window, rather than the band position of the intermediate layer, is a criterion for identifying interface charge transfer direction. This finding can offer different perspectives for designing high-performance semiconductor heterojunctions with suitable potential windows for solar energy conversion and storage.

Strong Interfacial Chemical Bonding in Regulating Electron Transfer and Stabilizing Catalytic Sites in a Metal-Semiconductor Schottky Junction for Enhanced Photocatalysis.

The weak electronic interaction at metal-photocatalyst heterointerfaces often compromises solar-to-fuel performance. Here, a trifunctional Schottky junction, involving chemically stabilized ultrafine platinum nanoparticles (Pt NPs, ≈3nm in diameter) on graphitic carbon nitride nanosheets (CNs) is proposed. The Pt-CN electronic interaction induces a 1.5% lattice compressive strain in Pt NPs and maintains their ultrafine size, effectively preventing their aggregation during photocatalytic reactions. Density functional theory calculations further demonstrate a significant reduction in the Schottky barrier at the chemically bonded CN-Pt heterointerface, facilitating efficient interfacial electron transfer, as supported by femtosecond transient absorption spectra (fs-TAS) measurements. The combined effects of lattice strain, stabilized Pt NPs, and efficient interfacial charge transport collaboratively enhance the photocatalytic performance, leading to over an 11-fold enhancement in visible light H2 production (8.52mmolg-1 h-1 ) compared to the CN nanosheets with the in situ photo-deposited Pt NPs (0.76mmolg-1 h-1 ). This study highlights the effectiveness of strong metal-semiconductor electronic interactions and underscores the potential for developing high-efficiency photocatalysts.

Sll1252 Coordinates Electron Transport between Plastoquinone and Cytochrome b6/f Complex in Synechocystis PCC 6803.

A mutant, Δsll1252ins, was generated to functionally characterize Sll1252. Δsll1252ins exhibited a slow-growth phenotype at 70 µmol photons m-2 s-1 and glucose sensitivity. In Δsll1252ins, the rate of PSII activity was not affected, whereas the whole chain electron transport activity was reduced by 45%. The inactivation of sll1252 led to the upregulation of genes, which were earlier reported to be induced in DBMIB-treated wild-type, suggesting that Sll1252 may be involved in electron transfer from the reduced-PQ pool to Cyt b6/f. The inhibitory effect of DCMU on PSII activity was similar in both wild-type and Δsll1252ins. However, the concentration of DBMIB for 50% inhibition of whole chain electron transport activity was 140 nM for Δsll1252ins and 300 nM for wild-type, confirming the site of action of Sll1252. Moreover, the elevated level of the reduced-PQ pool in Δsll1252ins supports that Sll1252 functions between the PQ pool and Cyt b6/f. Interestingly, we noticed that Δsll1252ins reverted to wild-type phenotype by insertion of natural transposon, ISY523, at the disruption site. Δsll1252-Ntrn, expressing only the C-terminal region of Sll1252, exhibited a slow-growth phenotype and disorganized thylakoid structure compared to wild-type and Δsll1252-Ctrn (expressing only the N-terminal region). Collectively, our data suggest that Sll1252 regulates electron transfer between the PQ pool and the Cyt b6/f complex in the linear photosynthetic electron transport chain via coordinated function of both the N- and C-terminal regions of Sll1252.

Development of a novel three-dimensional biofilm-electrode system (3D-BES) loaded with Fe-modified biochars for enhanced pollutants removal in landfill leachate

Different mass ratio iron (Fe)-loaded biochars (FeBCs) were prepared from food waste and used in the three-dimensional biofilm-electrode systems (3D-BES) as particular electrodes for landfill leachate treatment. Compared to the unmodified biochar (BC), specific surface area of Fe-loaded biochars (FeBC-3 with a Fe: biochar of 0.2:1) increased from 63.01 m2/g to 184.14 m2/g, and pore capacity increased from 0.038 cm3/g to 0.111 cm3/g. FeBCs provided more oxygen-containing functional groups and exhibited excellent redox properties. Installed with FeBC-3 as particular electrode, both NH4+-N and chemical oxygen demand COD removals in 3D-BESs were well fitted with the pseudo-first-order model, with the maximum removal efficiencies of 98.6 % and 95.5 %, respectively. The batch adsorption kinetics experiments confirmed that the maximum NH4+-N (7.5 mg/g) and COD (21.8 mg/g) adsorption capacities were associated closely with the FeBC-3 biochar. In contrast to the 3D-BES with the unmodified biochar, Fe-loaded biochars significantly increased the abundance of microorganisms being capable of removing organics and ammonia. Meanwhile, the increased content of dehydrogenase (DHA) and electron transport system activity (ETSA) evidenced that FeBCs could enhance microbial internal activities and regulate electron transfer process among functional microorganisms. Consequently, it is concluded that Fe-loaded biochar to 3D-BES is effective in enhancing pollutant removals in landfill leachate and provided a reliable and effective strategy for refractory wastewater treatment.

Defective S‐TiO2−x/CeO2 Heterojunction for Mutual Reinforcing Chemodynamic/Sonocatalytic Antibacterial Therapy and Sonoelectric/Ion‐Activated Bone Regeneration

AbstractSonocatalysis and chemodynamics have attracted widespread attention in antibacterial therapy. The transfer efficiency of electrons plays an important role in sonocatalysis and chemodynamics, and how to regulate electron transfer and achieve mutual‐reinforcement between sonocatalysis and chemodynamic to achieve efficient antibacterial therapy is a difficult problem. Here, this study develops a defective S‐doped TiO2 and CeO2 heterojunction(S‐TiO2−x/CeO2）sonosensitizer that can enhance chemodynamic therapy by regulating valence transitions of CeIII/CeIV by sonoelectrons, and enhancing sonocatalytic therapy by creating heterojunctions to accelerate the transfer of interface electron, thereby achieving mutual reinforcement of sonocatalysis and chemodynamic. It could kill 99.3% of S. aureus under ultrasound (US) irradiation . Due to the presence of mixed valence states CeIII/CeIV in CeO2, S‐TiO2−x/CeO2 could be as oxy‐substrates. Ce4+ can deplete glutathione and reacts with H2O2 in bacteria to produce reactive oxygen species (ROS). These activities combines with ROS generated from sonocatalysis, resulting in bacterial death. Meanwhile, the electrical signal generated by S‐TiO2−x/CeO2 under US stimulation and the cerium ions could activate the Wnt/β‐catenin signaling pathway to induce hBMSCs to differentiate into osteoblast. S‐TiO2−x/CeO2 successfully treats osteomyelitis under US irradiation by effectively clearing infection, suppressing inflammatory, and promoting bone regeneration, and it provides effective treatment for patients with deep infection.

Regulation Mechanism of Electron Transfer Reaction from Cytochrome C to Cytochrome C Oxidase

The respiratory chain in mitochondria is quite essential for the energy generation in cells, effectively producing “the energy currency in living organisms”, ATP. The driving force for this system is a series of electron transfers form Complex I (NADH:quinone oxidoreductase) to Complex IV (Cytochrome c Oxidase; CcO) in inner mitochondria membrane, and these electron transfer reactions promote the proton pumping from the matrix to the intermembrane space in mitochondria, and, by use of the resulting proton concentration gradient across the membrane, Complex V (ATP synthase) produces ATP. These series of electron transfer reactions terminate at CcO to reduce molecular oxygen to water molecules. The electrons required for this four-electron reduction of molecular oxygen in CcO are donated from a small soluble electron transfer hemoprotein, Cytochrome c (Cyt c), and this electron transfer is also associated with the proton pumping for the ATP generation in the respiratory chain. To examine the molecular regulation mechanism of the electron transfer reaction to terminate the electron transport chain for four-electron reduction of molecular oxygen and proton pumping for the ATP generation, we kinetically followed the electron transfer reaction and analyzed the electron transfer reaction by the Michaelis-Menten equation. By utilizing the Cyt c mutants, we identified the amino acid residues to regulate the electron transfer reactions (Biochem. J., 2020, 477,1565). The kinetic analysis of the electron transfer reaction also revealed that the apparent rate for the electron transfer reaction determined by the steady-state kinetics is much slower than the intramolecular electron transfer rate in the Cyt c – CcO complex. On the other hand, we successfully determined the interaction site between Cyt c and CcO by using NMR (Proc. Natl. Acad. Sci., 2011, 108, 12271) and protein-protein docking simulation (J. Biol. Chem., 2016, 291, 15320). The Cyt c – CcO complex structure estimated from the NMR and protein-protein docking simulation clearly showed that the two redox centers, heme iron in Cyt c and CuA in subunit II of CcO, were located more than 20 Å apart, and the complexes exhibiting shorter redox center distances were energetically unstable. Combined with the results from kinetic and structural studies, we proposed a “conformationally gated electron transfer mechanism”, where the thermal fluctuation of the protein structure controls the electron transfer rate. However, direct experimental evidence that protein conformational fluctuations regulate electron transfer reactions has not been obtained. In this study, we focused on the viscosity of the protein solution as a factor to regulate the conformational fluctuation of the proteins, based on the assumption that high viscosity of the solution suppresses the conformational fluctuation. The electron transfer reaction from Cyt c to CcO was examined in the high viscosity solution and NMR relaxation measurements under high viscosity were also performed to identify the local structural fluctuation responsible for the regulation of the electron transfer rate. Together with the transient complex structures between Cyt c and CcO estimated by the MD simulation, the regulation mechanism of the electron transfer from Cyt c to CcO based on the “conformational gating” will be discussed.

Confining charge-transfer complex in a metal-organic framework for photocatalytic CO2 reduction in water

In the quest for renewable fuel production, the selective conversion of CO2 to CH4 under visible light in water is a leading-edge challenge considering the involvement of kinetically sluggish multiple elementary steps. Herein, 1-pyrenebutyric acid is post-synthetically grafted in a defect-engineered Zr-based metal organic framework by replacing exchangeable formate. Then, methyl viologen is incorporated in the confined space of post-modified MOF to achieve donor-acceptor complex, which acts as an antenna to harvest visible light, and regulates electron transfer to the catalytic center (Zr-oxo cluster) to enable visible-light-driven CO2 reduction reaction. The proximal presence of the charge transfer complex enhances charge transfer kinetics as realized from transient absorption spectroscopy, and the facile electron transfer helps to produce CH4 from CO2. The reported material produces 7.3 mmol g−1 of CH4 under light irradiation in aqueous medium using sacrificial agents. Mechanistic information gleans from electron paramagnetic resonance, in situ diffuse reflectance FT-IR and density functional theory calculation.

Directly Imaging and Regulating the Nanoscale Inhomogeneity of S‐Vacancies in Molybdenum Disulfide Monolayer during Electrocatalytic Hydrogen Evolution

AbstractThe study of electron transfer event on two‐dimensional (2D) layered transition metal dichalcogenides has attracted tremendous attentions attributing to their promising applications in electrochemical devices. Herein, we demonstrate an opto‐electrochemical strategy to directly map and regulate electron transfer event on molybdenum disulfide (MoS2) monolayer by combining bright field (BF) imaging technique with electrochemical modulation. The heterogeneity of electrochemical activity on MoS2 monolayer down to nanoscale is resolved spatiotemporally. The thermodynamics of MoS2 monolayer is measured during electrocatalytic hydrogen evolution, and the Arrhenius correlations are obtained. We validate that the defect generation engineered by oxygen plasma bombardment dramatically enhances the local electrochemical activity of MoS2 monolayer, which can be attributed to point defects of S‐vacancies as evidenced. Furthermore, by comparing the difference of electron transfer event on MoS2 with various layers, the interlayer coupling effect is uncovered. This study represents a facile method to image the heterogeneity of electrochemical properties for nanomaterials with atomic thickness and regulate the local activity within the plane by extrinsic factors. It also has potential applications in the design and evaluation of high‐performance layered electrochemical systems down to nanoscale.

Directly Imaging and Regulating the Nanoscale Inhomogeneity of S-Vacancies in Molybdenum Disulfide Monolayer during Electrocatalytic Hydrogen Evolution.

The study of electron transfer event on two-dimensional (2D) layered transition metal dichalcogenides has attracted tremendous attentions attributing to their promising applications in electrochemical devices. Herein, we demonstrate an opto-electrochemical strategy to directly map and regulate electron transfer event on molybdenum disulfide (MoS2 ) monolayer by combining bright field (BF) imaging technique with electrochemical modulation. The heterogeneity of electrochemical activity on MoS2 monolayer down to nanoscale is resolved spatiotemporally. The thermodynamics of MoS2 monolayer is measured during electrocatalytic hydrogen evolution, and the Arrhenius correlations are obtained. We validate that the defect generation engineered by oxygen plasma bombardment dramatically enhances the local electrochemical activity of MoS2 monolayer, which can be attributed to point defects of S-vacancies as evidenced. Furthermore, by comparing the difference of electron transfer event on MoS2 with various layers, the interlayer coupling effect is uncovered. This study represents a facile method to image the heterogeneity of electrochemical properties for nanomaterials with atomic thickness and regulate the local activity within the plane by extrinsic factors. It also has potential applications in the design and evaluation of high-performance layered electrochemical systems down to nanoscale.

Insights into Proteomics Reveal Mechanisms of Ethanol-Enhanced Bacterial Cellulose Biosynthesis by Komagataeibacter nataicola

Nata de coco, known as bacterial cellulose (BC), has been given much attention in the food industry and biomaterial areas due to its specific properties such as low calorie content, high content of fiber, high purity and high biocompatibility. Komagataeibacter spp. are indispensable microorganisms for BC production due to their highly efficient production. Here, proteomics was applied to investigate the metabolism regulation mechanisms of BC yield improvements in K. nataicola Y19 by 48 ± 3% after ethanol supplementation. The results evidenced that differentially expressed proteins involved in the BC biosynthesis system, glycolytic pathway, TCA cycle and oxidative phosphorylation process were up-regulated. The proteins accelerated the BC biosynthesis by providing more energy and via intermediate metabolites. Furthermore, the elongation factor Tu, chaperone DnaK and translocase subunit SecB may be involved in the BC synthesis procedure by regulating electron transfer, hydrolysis of ATP and protein transformation. Moreover, the ethanol-enhanced BC biosynthesis may be associated with the decreased expression of endoglucanase. This research elucidates the proteomics mechanism of higher BC production based on ethanol addition, providing references for nata de coco production efficiency and the synthetic regulation of bacterial cellulose in the future.

Understanding the mechanism of saturated and mono-/tri-lacunary Keggin SiWx doped in Bi2WO6 and BiOBr for efficient photocatalytic CO2 reduction

Different from the doping of common simple ions, polyoxometalates (POMs) with the ability to regulate electron transfer as a large dopant and their doping mechanism is rarely studied. In this work, saturated and mono-/tri-lacunary Keggin SiWx (x = 9, 11, 12) have been successfully doped in Bi2WO6 and BiOBr through a two-step hydrothermal method, respectively, in which SiWx respectively replaced WO42− of Bi2WO6 and Br− of BiOBr, and are denoted as SiWx-Bi2WO6 and SiWx-BiOBr. As a shallow electron trap, SiWx inhibits photoinduced carrier recombination of Bi2WO6 and BiOBr. Besides, SiWx-Bi2WO6 and SiWx-BiOBr behave differently in photocatalytic CO2 reduction, which the CO yields of SiW9-Bi2WO6, SiW11-Bi2WO6 and SiW12-Bi2WO6 are 1.5, 3.3 and 6.2 times higher than Bi2WO6, while the CO yields of SiW9-BiOBr, SiW11-BiOBr and SiW12-BiOBr are 1.6, 2 and 2.6 times that of BiOBr. The corresponding reasons for the different performances can be attributed to the different hydrophobicity of the materials, reduction of the Bi2WO6 and BiOBr nanosheet stacking thickness and inhibition of carrier recombination. The deep insights into the influences of saturated and lacunary POMs on photocatalytic performances provide more ideas for the rational design of photocatalytic materials for CO2 reduction to high-valuable products.