Electron Transfer Research Articles

Mineralizing Biofilm towards Sustainable Conversion of Plastic Wastes to Hydrogen.

The integration of inorganic materials with biological machinery to convert plastics into fuels offers a promising strategy to alleviate environmental pollution and energy crisis. Herein, we develop a type of hybrid living material via biomineralization of CdS onto Shewanella oneidensis-based biofilm, which is capable of sustainable hydrogen production from poly(lactic acid) (PLA) wastes under daylight. We reveal that the formed biofilm microstructure provides an independent anaerobic microenvironment that simultaneously supports cellular viability, maintains hydrogenase activity, and preserves the functional stability of CdS, giving rise to the efficient plastic-to-hydrogen conversion efficiency as high as 3751 μmol H2 g-1 PLA. Besides, by genetically engineering transmembrane pili conduit and incorporating conductive nanomaterials to strengthen the electron transfer across cellular interface and biofilm matrices, we show that the conversion efficiency is further enhanced to 5862 μmol H2 g-1 PLA. Significantly, we exhibit that a long-term sustainable plastic-to-hydrogen conversion of 63 d could be achieved by periodically replenishing PLA wastes. Overall, by the synergistic integration of biotic-abiotic characteristics the developed biofilm-based biomineralized hybrid living material is anticipated to provide a new platform toward the efficient conversion of plastic wastes into valuable fuels, and bridge the gap between environmental contamination and green energy production.

Theoretical Insight into Antioxidant Mechanism of Caffeic Acid Against Hydroperoxyl Radicals in Aqueous Medium at Different pH-Thermodynamic and Kinetic Aspects

In this study, the DFT/M062X/PCM method was applied to investigate thermodynamic and kinetic aspects of reactions involved in possible mechanisms of antioxidant activity of caffeic acid against HOO● radicals in aqueous medium at different pH values. Kinetic parameters of the reactions involved in HAT (Hydrogen Atom Transfer), RAF (Radical Adduct Formation), and SET (Single Electron Transfer) mechanisms, including reaction energy barriers and bimolecular rate constants, were determined, and identification and characterization of stationary points along the reaction pathways within HAT and RAF mechanisms were performed. Inspection of geometrical parameters and spin densities of the radical products formed within HAT and RAF mechanisms revealed that they are stabilized by hydrogen bonding interactions and the odd electron originated through the reaction with the HOO● radical is spread over the entire molecule, resulting in significant radical stabilization. Thermodynamic and kinetic data collected in this study indicated that increasing pH of the medium boosts the antioxidant activity of caffeic acid by reducing the energy required to generate radicals within the RAF and/or HAT mechanism and, at extremely high pH, where the trianionic form of caffeic acid is a dominant species, by the occurrence of an additional fast, diffusion-limited electron-related channel.

Structure of dimerized assimilatory NADPH-dependent sulfite reductase reveals the minimal interface for diflavin reductase binding.

Sulfur is one of the essential building blocks of life. Sulfur exists in numerous redox states but only one can be incorporated into biomass - S 2- (sulfide). In Escherichia coli , a protein enzyme called sulfite reductase reduces sulfite by six electrons to make sulfide. Typical electron transfer reactions move one or two electrons at a time, so this chemistry is unique. E. coli SiR is a two-protein complex composed of a diflavin reductase flavoprotein and an iron metalloenzyme hemoprotein. Until now, the molecular interactions that govern subunit interactions remained a mystery because the extreme flexibility of the flavoprotein subunit, which has challenged X-ray or cryo-EM analysis for over 30 years. In overcoming these challenges, we used a combination of rapid plunging with a high critical-micelle-concentration lipid alongside a biochemically minimized complex to determine the 2.78 Å-resolution cryo-EM structure of a dimer between the flavoprotein and hemoprotein subunits.

Surface-bound Fe(0) and Fe(II) mediated by 2-picolinic acid functionalized zero-valent iron for highly Cr(VI) removal

Electron transfer of zero-valent iron (ZVI) is significantly impeded by its oxide layer, and limiting its removal of pollutants. In this study, 2-picolinic acid (PA) and ZVI were co-ball milled to improve electron transfer in ZVI (PA-ZVIbm), and used for the removal of heavy metal Cr(VI). Characterization analysis showed that the presence of electron-rich groups on the surface of PA-ZVIbm promoted the transfer of electrons from the Fe(0) core to the surface, and the surface Fe(0) and Fe(II) contents increased from 1.1 % to 6.3 % and from 60.2 % to 72.9 %, respectively, effectively reducing Cr(VI) through an electron transfer mechanism. Theoretical calculations showed that the modification of PA enhanced the adsorption of Cr(VI) on the ZVI surface, and the adsorption energy decreased from −3.561 eV to −5.119 eV. PA-ZVIbm showed strong advantages in the removal of Cr(VI), with a reaction rate constant and adsorption capacity 17 and 13 times that of ZVIbm, respectively, and a conversion rate of 100 %. Moreover, PA-ZVIbm showed excellent performance over a wide pH range (3−10) and under different coexisting ions, while being cost-effective and having low environmental risks. This study explored the relationship between ZVI surface modification and performance, and provided new insights into the modification of ZVI using small molecule oxygen-containing organic acids.

Deciphering the role of biochar pseudocapacitance strengthening in promoting syntrophic methanogenesis: Microbial capacitance-tropism in propionate metabolism

The redox functional groups of biochar can act as pseudocapacitance, alleviating acid accumulation and facilitating electron transfer in anaerobic digestion. Fe modification further enhances its pseudocapacitance properties. However, the specific role of pseudocapacitance strengthening in the electron transfer of volatile fatty acid syntrophic methanogenesis, as well as the factors inducing the enrichment behavior and metabolic mechanisms of microbes on its surface, remain unclear. In this study, experiments using acetate and propionate as substrates were conducted with the addition of biochar and electro-enhanced biochar, while 16S rRNA gene amplicon sequencing and metagenomic analysis were employed to investigate the underlying mechanisms. The results demonstrate that strengthening biochar’s pseudocapacitance significantly facilitates the electron shunt by accepting electrons, accelerating NADH/NAD+ conversion and ATP synthesis. This further promotes the oxidative degradation of propionate and acetate through the methylmalonyl-CoA (MMC) and syntrophic acetate oxidation (SAO) pathways. During methanogenesis, biochar directly transfers electrons to methanogens, with the strengthened pseudocapacitance further accelerating electron transfer through the CO2 reduction pathway and specifically promoting the methanation of propionate rather than acetate. Moreover, during propionate metabolism, Coprothermobacter and Methanosarcina exhibit capacitance-tropism in their enrichment on biochar, serving as key functional contributors to the biochar-microbial aggregates. These findings provide valuable insights for selecting exogenous materials in engineering applications to alleviate acid accumulation in anaerobic digestion systems.

Slow release performance of the immobilized carbon dots and their enhancing effect on anaerobic denitrification

Carbon dots (CDs) can improve microbial electron transfer rates and denitrification activities via entering the cells. To avoid the frequent addition of CDs in practical application, in this study, CDs were first covalently immobilized on bio-carrier polypropylene nonwoven fabrics. The immobilized CDs (iCDs) could be slowly released and enter the cells, thus enhancing the activities of the denitrifying-related enzymes and electron transfer system of Stutzerimonas stutzeri ATCC 17588, during which the nitrate removal rate was significantly increased by 47.2 % with the reduced accumulation of nitrite and N2O. During the tested 10 cycles, the iCDs exhibited stable accelerating performances on nitrate removal (an average increase of 39.9 %). Proteomics analysis showed that the slow-release performance of iCDs was mainly attributed to the catalytic effect of extracellular amidases and esterases. At the community level, the iCDs addition also resulted in the increase of denitrification rate mediated by the enriched denitrification community containing main genera Stutzerimonas, Thauera and Pannonibacter. Further metagenomics analysis showed that the three genera containing genes encoding amidases and denitrifying-related enzymes could perform denitrification process together via obtaining iCDs. These results indicate that iCDs are of potential application for the treatment of nitrate-containing wastewaters.

Study on the performance and mechanism of photocatalytic hydrogen production by NiO/ZnO-graphene composite materials under low irradiation conditions

Using different mass ratios of NiO, ZnO, and corn stover-based graphene (GR), NiO/ZnO-graphene (NZGR) composite photocatalytic materials, which demonstrated photocatalytic water splitting for hydrogen production under low irradiation, were prepared by an in-situ deposition method. The microstructure and optoelectronic properties of the NZGR materials were characterized. The heterostructure formed by NiO and ZnO in the photocatalytic NZGR material was coupled with the graphene-like structure of GR, resulting in the rapid transfer of electrons to the graphene surface, causing electron accumulation and ensuring the ability of the material to produce hydrogen by the photocatalytic decomposition of water under low irradiation. Under the optimal mixing ratio of the components of the NZGR photocatalyst with a graphene mass fraction of 30 %, hydrogen production exhibited the highest rate and was 350 times faster than the photocatalytic hydrogen production of NiO/ZnO under the same conditions. This study provides a new approach to producing hydrogen by the photocatalytic decomposition of water under low irradiation conditions.

Carbon-based nanomaterials enhance the growth of cable bacteria in brackish sediments

Cable bacteria are long, multicellular bacteria that conduct electrical currents over centimetre distances within sediment to support their metabolism. Recent studies have shown their potential for extracellular electron transport (EET), allowing the possibility to donate electrons to solid electrodes and potentially enabling electrical interactions with other microbes. However, the mechanisms and capabilities of their EET, and their potential to interact electronically with other materials in their environment has not been explored. As sediment can contain conductive minerals, this study aimed to investigate the effect of carbon-based colloidal nanomaterials such as graphene oxide (GO), sulfur-doped graphene oxide (S-GO), and carbon nanotubes on cable bacteria. When S-GO was added to sediment, cable bacteria grew with higher activity, and in higher density at depth, whilst GO had little initial effect but showed a delayed enhancement of cable activity. This is thought to be due the reduction of GO via iron oxidation within the sediment, allowing it to become more conjugated, resulting in more similar conductive properties to S-GO. We speculate that the enhancement of cable bacteria growth is due to the electron shuttling properties of S-GO and similar materials, allowing for more efficient transfer of electrons between cable bacteria and to electron acceptors.

Precisely Engineering of Ångström‐Scale Dual Single Atom Drive [Co‐O] Spin‐Orbit Coupling to Boost Lithium–Oxygen Batteries Electrocatalysis

AbstractDual‐atom catalysts (DACs) have emerged as a novel area of investigation in lithium–oxygen (Li‐O2) batteries due to their distinctive synergistic mechanisms. However, achieving precise control of the active site structure and unraveling the synergistic effects of bimetallic species remains a significant challenge. Here, the study reports a pre‐encapsulated pyrolysis strategy using a Co‐based Robson‐type binuclear complex as a precursor to mediate the synthesis of dual single‐atom Co (Co‐DAC) with precise angstrom‐scale inter‐site distance configuration, serving as an efficient catalyst for Li‐O2 batteries. The tailored structure induces significant charge redistribution, reducing crystal field splitting energy (ΔO). The high‐spin Co species generate a strong electronic driving force, forming flexible σ and δ‐like bonds with the crucial oxygen intermediate (*O). Simultaneously, enhanced Co‐O spin‐orbit coupling facilitates electron transport along the bridging O‐channel, forming highly active Co‐O‐O‐Co electron chains that synergistically adsorb *O, establishing a favorable reaction pathway. Significant optimization of Li‐O2 batteries redox kinetics is achieved based on the well‐defined local structure of dual single‐atom Co sites. This work enhances the understanding of the dependence between rational design of custom structures and corresponding electron transfer dynamics, while providing new strategies and theoretical guidance for DACs to help develop high‐performance Li‐O2 batteries.

Novel cobalt-doped CuFe2O4 spinel catalyst for enhanced peroxymonosulfate activation to achieve rapid degradation of tetracycline hydrochloride: Dominant roles of O2[rad]- and 1O2 in the oxidation process

Heterogeneous peroxymonosulfate (PMS) catalysis is a promising method for water pollution treatment. CuFe2O4 spinel can activate PMS, but its application is limited by its tendency to agglomerate and its low-mass transfer efficiency. In this study, a cobalt-doped CuFe2O4 (CuFeCoO4, CFCo-1) was successfully synthesized, achieving a degradation efficiency of 98.36 % for tetracycline hydrochloride (TCH) within 21 min, with a high degradation rate corresponding to a kinetic constant of 0.2041 min−1. CFCo-1 demonstrated strong resistance to interference from inorganic ions and organic compounds. It maintained over 90 % TCH removal efficiency with negligible leaching of metal ions after five cycles, indicating that the catalyst had strong cyclic stability. Mechanistic analysis revealed that cobalt doping improved the electron transfer efficiency of the catalyst, enabling CFCo-1 to activate PMS and degrade the pollutant through both radical (OH, SO4- and O2-) and non-radical (1O2) pathways, with O2- and 1O2 being the dominant species. The potential degradation pathways of TCH were proposed based on theoretical calculation and the identification of degradation products. In conclusion, cobalt doping is an effective strategy for enhancing the catalytic performance of spinel for efficient degradation of pollutants in water.

Atomic mechanisms of oxidative behavior of ferrochromium alloys by water-oxygen environment

The formation of chromium-rich oxide layers on the surface of Fe-Cr alloys significantly impacts their performance at elevated temperatures. Understanding the formation process of these oxide layers at the atomic scale is crucial for further elucidating oxidation behavior, though it presents substantial challenges. In this study, ReaxFF molecular dynamics simulations were used to investigate the oxidation behavior of Fe-Cr alloys in high temperature water vapor and oxygen environments. The results demonstrate that chromium atoms are the primary contributors to the oxidation process, with Cr atoms diffusing to the surface more readily than iron atoms, leading to uneven stress distribution and creating high-stress regions near the Cr atoms. Additionally, hydrogen atoms generated from the breakdown of water molecules infiltrate the alloy matrix, promoting the creation, movement, and clustering of cation and anion vacancies, thereby enhancing oxidation reactions in high-temperature, humid conditions. The study further analyzes electron transfer during single-atom chemical reactions and explores the linear relationship between varying Cr content (10 %–30 %) and oxidation behavior under identical environmental conditions. These findings provide an important theoretical basis for optimizing the performance of Fe-Cr alloys for applications in high temperature environments.

MIL-88-derived porous carbon rod-supported FePS3 nanosheet arrays for robust sodium storage

Ternary metal phosphorus trisulfide (MPS3) has emerged as an excellent candidate for use as an anode in sodium-ion batteries, characterized by its unique layered structure, easily tunable physicochemical properties, and high theoretical capacity. However, its intrinsic challenges such as low electrical conductivity and susceptibility to fragmentation have led to unsatisfactory rate and cyclic capability. Herein, the intriguing microcomposite structure of porous carbon rod-supported FePS3 nanosheet arrays (FePS3@CR) is ingeniously constructed in situ via the phospho‑sulfurization of MIL-88. FePS3@CR showcases multiple structural advantages, including enhanced electrical conductivity, increased surface area, accelerated electron transfer rate, and mitigated structural stress. These combined benefits endow FePS3@CR with improved rate capability (808.0 and 474.3 mAh g−1 at 0.1 and 10 A g−1, respectively) and cyclic life (94.5 % retention after 1500 loops at 2 A g−1). The assembled full battery also demonstrates robust cycling stability, retaining 94.2 % of its capacity after 1100 loops at 0.5 A g−1. The specific sodium storage process of the FePS3 electrode is investigated through ex-situ structure analysis. This work presents innovative structural designs potentially improving the energy storage performance of MPS3 material system.

Carbonised Typha tassel-modified enzymatic electrodes for ferrocene-mediated glucose biosensor and glucose/air biofuel cell applications

This study demonstrates the application of carbonised Typha tassel (CTT) in ferrocene-mediated enzymatic glucose biosensing and enzymatic biofuel cell (EnBFC) applications. Typha tassel was carbonised under an inert atmosphere to obtain conductive CTT which was then mixed with an effective electron transfer mediator, ferrocene (Fc) obtaining a redox-active electrode material. The successful immobilisation of the glucose oxidase (GOx) enzyme was performed on a CTT-Fc modified screen-printed electrode followed by a chitosan protective coating. The resulting enzymatic electrode was electrochemically characterised as a glucose biosensor with a working range of 0–10 mM and LOD and LOQ values of 0.19 mM and 0.56 mM, respectively. The developed glucose biosensor also showed good reproducibility and reusability with RSD% values of 6.68 % and 8.75 %, respectively. Furthermore, a real sample demonstration was performed using commercial jam samples with good recovery values. Finally, an EnBFC demonstration was performed using the enzymatic biosensor as an anode and a non-enzymatic cathode prepared using platinum black on gas diffusion carbon electrodes reaching a maximum power density of 3.6 µW cm−2. This study shows the promise of CTT as an alternative to conventional materials in enzymatic biosensor and bioelectronic applications as a suitable, cheap, and sustainable material.

Solvent-modified carbon nitride integrated with SiO2 for enhanced photocatalytic activity: Microstructural modification and catalytic mechanisms

The photocatalytic activity of carbon nitride (CN) materials is primarily limited by low photogenerated carrier separation and mobility. The solvothermal method can regulate the molecular structure of materials to enhance charge separation and transport. In this study, we used ethanol (EtOH), DMF, and deionized water (H2O) as solvents to customize the microstructure of CN through a one-step solvothermal method and loaded SiO2 onto CN, ultimately synthesizing SiO2/CN composites (SiCNX, where X = E, D, H) with significantly improved photocatalytic efficiency. The modification with these three solvents led to noticeable changes in the basic structure of CN, reflected in the number of carbon vacancies, the integrity of the tri-s-triazine ring framework, the degree of polymerization, and the presence of C–C/CC bonds. The SiCNE composite, synthesized with ethanol modification, stood out by demonstrating exceptional photocatalytic degradation ability for Rhodamine B (RhB), achieving 99 % decolorization of a high-concentration RhB solution (300 mg/L) in 35 min. Additionally, the performance of SiCNE is 6.24 times that of CN and 224 times that of SiO2. This study not only exhibits the potential of solvent-modified SiCNX in constructing efficient electron transfer pathways but also highlights its capability in remarkably improving photocatalytic performance, providing a promising avenue for the development of future photocatalytic materials.

Hierarchical cocoon-like Co9S8-N@NC for ambient reduction of sulphur dioxide to sulphur via proton-coupled electron transfer

Electrochemical SO2 reduction reaction (SO2RR) is an attractive approach for recycling sulphur resources at room temperature, but this is difficult to achieve in solution owing to the interference of complex oxysulphur anions caused by SO2 conversion. Herein, a silkworm cocoon-like Co9S8-N@NC heterostructure (denoted as CoDC-pn) was constructed for SO2RR in protonic acid. This unique heterostructure induces the electron-deficient Co sites on CoDC-pn that promote SO2 activation and retard hydrogen evolution side-reaction. CoDC-pn delivers a S8 yield rate of 113.1 μmol h−1 mgcat−1 and faradaic efficiency of 70.0 % at –0.1 V. In-situ characterizations and mechanistic investigations confirm that SO2RR is a proton-coupled electron transfer process, in which protons can effectively inhibit the adverse conversion of SO2 to other oxysulphur species and attend the successive hydrodeoxygenation of *SO2 to *S followed by parallel atomic S polymerization for S8 formation. These findings provide a creative route and insight for exploring highly selective SO2-to-S8 conversion at ambient conditions.

Ultrasensitive electrochemiluminescencent multivalent aptamer sensor based on energy and electron transfer dual quenching tactics.

Anefficient "on-off-on" electrochemiluminescence (ECL) aptasensor utilizing dual-mechanism quenching was constructed for detecting furanyl fentanyl (FuF). The first signal "on" state was achieved by novel dual-ligand zinc metal-organic frameworks (Zn-MOFs), which were synthesized by self-assembly reaction using zinc atom clusters as metal nodes, achieving strong and stable ECL emission. The "off" state was realized by the energy and electron quenching effect of copper-doped WO3. Specifically, in addition to the overlap of the UV-Vis spectrum, energy transfer existed between the acceptor and donor after doping copper. Therefore, copper created a "highway" for electron transfer between the donor and acceptor, which greatly improved the quenching efficiency. Simultaneously, employing multivalent aptamers as capture probes augmented the binding affinity and probability of association between aptamer and target through a synergistic multivalent effect. Consequently, the second "on" state was the ECL signal restored by introducing FuF. Benefiting from the combination of the multivalent aptamers strategy with the "on-off-on" design, the developed aptasensor showed excellent linearity (1.0 × 10-13 to 1.0 × 10-6 g/L) with a low limit of detection of 5.5 × 10-14 g/L (S/N = 3). Additionally, it demonstrates a relative standard deviation (RSD) of less than 5% and good recovery ranging from 97.6 to 102%. The proposed aptasensor presents considerable potential for rapid, sensitive, and accurate determinationof FuF.

Structure tunning of MoS2@Fe3O4 by modulating electron density for enhanced Fenton-like PMS activation: Accelerated Fe (III)/Fe (II) cycle for efficient micropollutants removal

1T-MoS2 is a promising material for regulating the electronic structure of Fe-based catalyst to enhance PMS activation, due to the higher chemical reactivity of the basal plane with excellent intrinsic electronic properties. Herein, an excellent MoS2@Fe3O4 by using 1T- MoS2 as support to tune electronic structure, labeling as 1T-MoS2@Fe3O4, was successfully synthesized for faster and enhanced micropollutants degradation via Fenton-like peroxomonosulfate (PMS) activation. The composite showed remarkable catalytic performance, as evidenced by a removal rate of 1.12 × 10−1 min−1 for caffeine, which was 4.50 times higher than that of 2H-MoS2@Fe3O4, attributed to the robust capacity for Fe (II) regeneration. The efficiency of the 1T-MoS2@Fe3O4/PMS system was affected by pH, PMS and catalyst dosages, as well as water chemistry. Additionally, the potential mechanism for PMS activation was explored, showing that O2• were the dominant reactive oxygen species (ROS) generated in the system due to the electron-rich O sites on the composite, and electron transfer processes play an important role during PMS activation. The Mo (IV) active sites facilitated accelerated Fe (III)/Fe (II) cycle, which promoted the rapid PMS activation. Excellent degradation of micropollutants (MPs) mixture in real secondary effluent was achieved by 1T-MoS2@Fe3O4/PMS system. The possible degradation pathways of caffeine (CAF), ibuprofen (IBP), and carbamazepine (CBZ) were also investigated. This study offers a new perspective on MoS2 as a co-catalyst/support within Fenton-like system.

Cation‐Vacancy Engineering Modulated Perovskite Oxide for Boosting Electrocatalytic Conversion of Polysulfides

AbstractLithium‐sulfur batteries face challenges like polysulfide shuttle and slow conversion kinetics, hindering their practical applications in renewable energy storage and electric vehicles. Herein, a solution to solve this issue is reported by using a cation vacancy engineering strategy with rational synthesis of La‐deficient LaCoO3 (LCO‐VLa). The introduction of cation vacancies in LCO‐VLa modifies the geometric structure of coordinating atoms, exposing Co‐rich surface with more catalytically active surfaces. Meanwhile, the d‐band center of LCO‐VLa shifts toward the Fermi level, enhancing polysulfide adsorption. Furthermore, multivalent cobalt ions (Co3+/Co4+) induced by charge compensation enhance the electrical conductivity of LCO‐VLa, accelerating electron transfer processes and improving catalytic performance. Theoretical calculations and experimental characterizations demonstrate that La‐deficient LCO‐VLa effectively suppresses the polysulfide shuttle, reduces the energy barrier for polysulfide conversion, and accelerates redox reaction kinetics. LCO‐VLa‐based batteries demonstrate exceptional rate performance and cycling stability, retaining 70% capacity after nearly 500 cycles at 1.0 C, with a minimal decay rate of 0.055% per cycle. These findings highlight the significance of cation vacancy engineering for exploring precise structure‐activity relationships during polysulfides conversion, facilitating the rational design of catalysts at the atomic level for lithium‐sulfur batteries.

Synthetically modified mixed phase inverse spinel CuFe2O4 magnetic nanoparticles: Structure, physical, and electrochemical properties for photocatalytic applications

Copper ferrite nanoparticles with crystallite sizes between 21.8 and 27.0 nm are developed by modified co-precipitation (C), two-step hydrothermal (H), and polymer-assisted sol-gel (S) methods. The synthetic conditions caused a structure and morphology variation, resulting in their optoelectrical and electrochemical properties becoming markedly different for specific photocatalytic applications. The nanoparticles are p-type semiconducting with direct optical band-gaps between 2.06 and 2.65 eV and carrier concentrations between 1017 ∼1018 cm−3. Magnetization studies demonstrate that the C-sample exhibits saturation magnetization of 32.44 emu/g nearly double as compared to that of H-sample (16.4 emu/g); however, the latter shows the highest coercivity. Impedance spectroscopy reveals faster electron transfer kinetics across the grain boundaries in the S-sample. The pellets prepared from C- and S- samples have larger dielectric constants and better oxygen ion-led conductivity owing to their larger grain size. Density Functional Theory-based calculation shows that oxygen ion conductivity plays a vital role in hole transport and thus an enhancement in the photocatalytic properties. Photocatalytic activity in the H-sample is superior with a degree of methylene blue dye degradation of 55 % in 2 h and a faster rate kinetics of 0.004 min−1 in the first hour under simulated sunlight.

Na, Mg, and Ca as promoters for N2O adsorption on char surface: A theoretical study

This study aims to evaluate the impact of Na, Mg and Ca on the adsorption of N2O by char based on density-functional theory (DFT) at M06-2X/6-311G(d) level using pristine zigzag (PZ) char models with and without lactone group. The adsorption energy, the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gap, electrostatic potential (ESP), electron density difference (EDD), atomic dipole moment corrected hirshfeld (ADCH) charge, and the weak intermolecular interactions were analyzed. Results show that the metal incorporation has little effect on the carbonaceous structure but significantly promotes the adsorption of N2O on char. Further investigations suggest that the metal incorporation induces more valence electrons, and enhances the electron transfer between the metals and carbon surface, thus facilitating char activity to adsorb N2O. Overall, this study provides new insights into the mechanisms of N2O adsorption by heteroatom-incorporation char.