Electron Transfer Mechanism Research Articles

Energy-Transfer Enabled 1,4-Aryl Migration.

Functional group translocation is undoubtedly a pivotal synthetic transformation in organic chemistry. Numerous types of reactions involving radical 1,2-aryl or 1,4-aryl migration via electron transfer mechanism have been extensively investigated. Nevertheless, energy-transfer enabled 1,4-arylation remains unknown. Herein we disclose that an unprecedented di-π-ethane rearrangement featuring 1,4-aryl migration facilitated by energy transfer catalysis under visible light conditions. The newly developed mild protocol exhibits tolerance towards diverse functional groups and enables the migration of a multitude of aromatic rings, encompassing both electron-withdrawing and electron-rich functional groups. The open-shell strategy has also found successful application in the modification of several drugs. Large-scale experiments, continuous-flow experiment, and versatile manipulation of products have demonstrated the robustness and potential utility of this synthetic method. Preliminary mechanistic studies have supported the involvement of radical species in this di-π-ethane rearrangement and have also provided evidence for the energy transfer mechanism.

Energy‐Transfer Enabled 1,4‐Aryl Migration

Functional group translocation is undoubtedly a pivotal synthetic transformation in organic chemistry. Numerous types of reactions involving radical 1,2‐aryl or 1,4‐aryl migration via electron transfer mechanism have been extensively investigated. Nevertheless, energy‐transfer enabled 1,4‐arylation remains unknown. Herein we disclose that an unprecedented di‐π‐ethane rearrangement featuring 1,4‐aryl migration facilitated by energy transfer catalysis under visible light conditions. The newly developed mild protocol exhibits tolerance towards diverse functional groups and enables the migration of a multitude of aromatic rings, encompassing both electron‐withdrawing and electron‐rich functional groups. The open‐shell strategy has also found successful application in the modification of several drugs. Large‐scale experiments, continuous‐flow experiment, and versatile manipulation of products have demonstrated the robustness and potential utility of this synthetic method. Preliminary mechanistic studies have supported the involvement of radical species in this di‐π‐ethane rearrangement and have also provided evidence for the energy transfer mechanism.

Exploring Interatomic Electron Transfer and Metal-Ligand Binding Mechanism in Trimethylenemethane Iron Tricarbonyl: Insights from Potentials per Electron and Corresponding Force Density Fields.

This study employs an analysis of the per-electron potentials and the superposition of the electrostatic and kinetic force fields, Fes(r) and Fk(r), and the gradients of the potential energy and one-electron densities to investigate the binding mechanism in trimethylenemethane iron tricarbonyl complex (TMM)Fe(CO)3. Our approach permits the delineation of the "ligand-binding" force field generated by the metal nucleus but partially operating within the ligand atoms. A mechanical rationale for metal-ligand interactions is thus presented: In the corresponding area, the attractive force Fes(r) provides the backdrop against which the homotropic static force (r) and the heterotropic kinetic force Fk(r) exert attractive and repulsive influences, respectively, toward the metal nucleus on a portion of the electrons belonging to the ligand atoms. This area thus represents electron sharing, which emerges as a quantum chemical response against the metal-to-ligand electron transfer. It has been demonstrated that the response is facilitated by the decreased potential energy density in the vicinity of the interatomic surface. Our findings indicate that the polar coordination bonds in (TMM)Fe(CO)3 exhibit notable quantum chemical responses. However, the previously described nonbonded contact also features an unexpectedly pronounced response, despite the absence of a bond path. It can be proposed that the unforeseen response is a consequence of the formation of the 18-electron, closed valence shell, rather than an indication of the establishment of an organometallic chemical bond.

Rational design of ZnO/SrTiO3 S-scheme heterojunction for photo-enhanced piezocatalytic hydrogen production

Photopiezocatalysis have been frequently investigated for hydrogen evolution reactions in recent years. Herein, ZnO, SrTiO3 and ZnO/SrTiO3 S-scheme heterojunction were investigated for photo/piezocatalytic hydrogen production. Piezocatalytic hydrogen production under ultrasonic vibration by using ZnO, SrTiO3 and ZnO/SrTiO3 was obtained as 270 µmol g-1h−1, 200 µmol g-1h−1 and 1265 µmol g-1h−1, respectively. In addition, ZnO/SrTiO3 S-scheme heterojunction showed 2200 µmol g-1h−1 photopiezocatalytic hydrogen production under simultaneous exposure to white LED light and ultrasonic sound. ZnO/SrTiO3 heterojunction displayed significantly higher hydrogen production rate due to the decreased charge recombination, increased charge transfer with strong piezoelectric polarization and internal electrical field. The piezoelectric effect of ZnO/SrTiO3 heterojunction is also confirmed by piezoresponse force microscope technique with butterfly and phase hysteresis loops. Also, piezoelectric coefficient of ZnO/SrTiO3 found about 2-folds higher than those of their pristine forms. Electron transfer and reaction mechanism of ZnO/SrTiO3 and activity differences are confirmed by advanced optical and electrochemical techniques such as diffuse reflectance spectroscopy, electronic impedance spectroscopy, Mott-Schottky calculation and chronoamperometry. The whole electrochemical measurements have been performed with or without mechanical stress and light irradiation, which signify their band bending properties, electron transfer mechanism and catalytic activities.

Structure-activity relationship between crystal plane and pyrite-driven autotrophic denitrification efficacy: Electron transfer and metagenome-based microbial mechanism

Pyrite-driven autotrophic denitrification (PAD) has been recognized as a promising treatment technology for nitrate removal. Although the occurrence of PAD has been found in recent years, there is a knowledge gap about effects of crystal plane of pyrite on the performance and mechanism of PAD system. Here, this study investigated the effects of crystal planes ({100}, {111} and {210}) of single-crystal pyrite on denitrification performance, electron transfer, and microbial mechanism in PAD system. The removal efficiency of nitrate in B-{210} reached 100%, which was 1.67-fold and 2.86-fold higher than that of B-{100} and B-{111}, respectively. X-ray photoelectron spectroscopy and electrochemical results indicated that Fe-S bonds of pyrite with {210} crystal plane were more susceptible to breakage by Fe3+ oxidation assault, and leaching microbially available Fe2+ and sulfur intermediates to drive autotrophic denitrification. Metagenomic results suggested that community of functional pyrite-driven denitrifiers varied in response to crystal plane, and abundances of N-S transformation and EET-related microbes and genes in B-{210} notably up-regulated compared to B-{100} and B-{111}. In addition, this work proposed a dual-mode for electron transfer pathway during pyrite oxidation and nitrogen transformation in PAD system. In B-{210}, Fe(II)- and sulfur-driven denitrifiers obtained electron after pyrite oxidation-dissolution, and the enrichment of pyrite-oxidizing bacteria in B-{210} could enhance the electron transfer from pyrite through electron shuttles. This work highlighted that stronger surface reactivity and electron shuttle effect in B-{210} enhanced electron transfer, leading to favorable PAD performance in B-{210}. Overall, this study provides novel insights into the structure-activity relationship between the crystal plane structure of pyrite and denitrification activity in PAD system.

New insights into the PFAS defluorination performance and mechanism of ultrasound-enhanced electrochemistry with peroxydisulfate electrolyte

Ultrasound (US)-assisted electrochemical oxidation (EO) has previously demonstrated its ability to degrade perfluorooctanoic acid (PFOA). However, the mechanisms of direct electron transfer and indirect oxidation by reactive oxygen species (ROS), as well as the involvement of these ROS, are unclear, particularly with the peroxydisulfate (PDS) electrolyte and the added effect of US. In this study, an US/EO/PDS system was first investigated, achieving nearly 100 % and 80.01 % defluorination for PFOA and perfluorooctane sulfonate, respectively (within 3 h). This US/EO/PDS system exhibited remarkable stability, pH tolerance, and practicality. Further experimental and theoretical studies revealed that the predominant mechanism of PFOA defluorination was indirect oxidation via ROS, rather than direct oxidation at the anode. Although none of these ROS could initiate the degradation of PFOA without additional energy, both ROS (SO4∙- ＞ •OH ＞ 1O2 ＞ O2∙-) and US/EO contributed to the initial step of PFOA defluorination. Furthermore, US enhanced the generation of ROS and the direct oxidation (electron transfer) ability of EO. The electrons were transferred from PFOA to PDS via the electrode assembly. This study clarified, for the first time, the synergistic effect of US/EO/PDS and the involvement of direct and indirect ROS oxidation in defluorination of PFOA, which shows potential for developing US and EO technology for complete degradation of polyfluoroalkyl substances.

Enhanced CO2-to-CH4 conversion via grain boundary oxidation effect in CuAg systems

The authentic active sites of oxide-derived copper (OD-Cu), namely grain boundaries (GBs) and oxidized Cuδ+ species, is still debatable, and their role in governing CH4 conversion remains unclear. Herein, this study answers these questions using bimetallic catalysts by novel electro-shock strategy with controllable GBs for the oxidization of Cuδ+ species by modulating Ag loading. The Ag enrichment at the GBs facilitates the bonding of oxygen with the uncoordinated Cu atoms, resulting in GB oxidation effect. The obtained CH4 selectivity is twice that of GBs or nanoalloy effect. The enhanced performance is attributed to the stable Cuδ+ species and unique electron transfer mechanism from GB oxidation structure. Operando attenuated-total-reflection Fourier-transform-infrared-spectroscopy unveils the reaction pathway of CO2-to-CH4 and the sluggish reversible quenching processes of intermediates. Theoretical calculations indicate that the weak *CO adsorption on GB oxidation structure facilitates *CO hydrogenation, promoting CO2-to-CH4 conversion.

Theoretical design of Z-scheme photocatalyst for water splitting with excellent catalytic performance: GeSe/PtS2 heterojunction

In the face of the urgent need for energy transition, Z-scheme heterojunctions are considered highly suitable candidates for future photocatalytic applications, owing to their exceptional optoelectronic characteristics and high catalytic efficiency. This paper systematically investigates the geometric structure, optoelectronic properties, and catalytic efficiency of the GeSe/PtS2 heterojunction through detailed first-principles calculations. The findings indicate that the band structure of the GeSe/PtS2 heterojunction presents a staggered Type-Ⅱ band alignment and exhibits an indirect band gap measuring 1.75 eV. Charge transfer analysis reveals that under the interplay of an intrinsic electric field directed from GeSe to PtS2 and the band bending occurring at the heterojunction interface, the GeSe/PtS2 heterojunction conforms to the obvious Z-scheme electron transfer mechanism characteristics. This facilitates the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) to proceed smoothly on opposite sides of the heterojunction. Across the pH range of 0 to 14, the heterojunction's band edge positions successfully span the redox potentials of water, and can still meet the hydrolysis potential requirements under strain. In addition, the GeSe/PtS2 heterojunction not only effectively compensates for the poor absorption of PtS2 monolayer to visible light, but also achieves a wider visible light absorption range through the strain-induced redshift in the spectrum. At the same time, the solar to hydrogen (STH) efficiency of up to 15.56% further underscores the substantial catalytic potential of the GeSe/PtS2 heterojunction, offering promising design strategies for a technological revolution in the field of photocatalysis.

In situ construction of Flowerlike bismuth oxide (BiO2-x)/N-rich carbon nitride (C3N5) S-scheme heterojunctions with enhanced structural defects for the efficient photocatalytic removal of tetracycline antibiotic and RhB

Efficient photocatalysts for the simultaneous removal of organic dyes and antibiotics are crucial for sustainable environmental management. In this study, we designed and synthesized a C3N5/BiO2-x S-type heterojunction photocatalyst with structural defects using a hydrothermal method, aimed at degrading both Rhodamine B (RhB) and tetracycline (TC). The degradation kinetic constants for RhB and TC were 0.0809 min−1 and 0.0535 min−1, respectively, showing improvements of 9.52 and 25.48 times over pure C3N5, and 2.90 and 1.49 times over BiO2-x. This enhanced performance is attributed to the unique electron transfer mechanism of the S-scheme heterojunction and the structural defects that facilitate efficient separation of electron-hole (e−-h+) pairs. Free radical trapping experiments indicated that the main reactive oxygen species (ROS) involved are ·O2− and h+. Additionally, electrochemical impedance spectroscopy (EIS) and transient photocurrent response (TPR) measurements confirmed improved separation and transfer of photogenerated e−-h+ pairs in the C3N5/BiO2-x heterojunction. The higher density of structural defects in C3N5/BiO2-x compared to individual BiO2-x counterparts enhances its ability to activate and photo-oxidize TC and degrade RhB. Consequently, C3N5/BiO2-x demonstrates significant potential as a photocatalyst for improving water quality.

Synthesis and structure of an aqueous stable Cu(II)-based coordination polymer with multifunctional fluorescence sensing property

Advanced methods for both biological and environmental hazardous pollutants are of sustained interest. Herein, a new coordination polymer, namely, [Cu2(OH)(1,2,4-bca)(bmoe)]·H2O (Cu-CP) has been hydrothermally constructed with a mix-ligand strategy, employing 1,2,4-benzenetricarboxylic acid (1,2,4-bca) and 1,1′-bis(1H-benzimidazolyl) oxydiethane (bmoe) as organic ligands. The intrinsic strong blue-light emission and the great stability in water solutions with the broad range of pH values (pH = 4 − 12) of Cu-CP provide a platform for practical fluorescence sensing application in water samples. Fluorescence measurements reveal that Cu-CP displays interesting multi-responsive dection activities toward toxic heavy-metal ions Cr2O72- / CrO42− / MnO4−, nitrofuran antibiotics nitrofurantoin (NFT) / nitrofurazone (NFZ) and acetylacetone (ACAC) in aqueous solutions achieving both high sensitivity and low detection limits (micromolar for Cr(VI) / Mn(VII) / ACAC and nanomolar for NFT / NFZ). Furthermore, the interference experiments have verified its excellent selectivity. A synergetic contribution of internal filtration effect (IFE) and Förster resonance energy transfer (FRET) between Cr2O72- / CrO42− / MnO4− and the framework of Cu-CP realize the fluorescence quenching behavior for Cr(VI) / Mn(VII) detection, while FRET, IFE and photoinduced electron transfer (PET) mechanisms are synergistically responsible in the case of NFT / NFZ, ACAC sensing supported by the molecular simulations and UV−vis spectral overlap experiments. This present work affords precious guidance for the effective and facile design and preparation of multifunctional luminescent coordination polymers with promising performance.

Revealing the essence of anion ligands in regulating amorphous MnOx to activate peracetic acid for micropollutant removal

How the anion ligands of manganese precursors affect the catalytic activity of amorphous manganese oxides (MnOx) in Fenton-like process is poorly understood. Here, five amorphous MnOx synthesized by Mn(II) precursors with different ligands were characterized and adopted to activate peracetic acid (PAA) for bisphenol A (BPA) degradation. Although > 90 % BPA removal was achieved in the five MnOx/PAA processes via both adsorption and oxidation, the oxidation kobs greatly differentiates by the ligands types with the order of MnOx-N > MnOx-S > MnOx-Cl > MnOx-AA > MnOx-OA. Ligands types would affect the specific surface area of MnOx and their ability to adsorb BPA, however which is not the decisive factor in determining the contaminant oxidation efficiency. Multiple experimental results indicate that the generation of oxygen vacancies induced by the ligands alters the Mn(III)/Mn(IV) ratio, ultimately contributing to the different efficiency of BPA oxidation driven by the direct electron transfer mechanism. Moreover, amorphous MnOx holds the promise of practical applications in catalytic PAA of various micropollutants with good stability. This study advances the fundamental understanding of ligand-regulated amorphous MnOx-catalyzed PAA process.

Recent Advances in Enzyme‐based Biofuel Cells Using Glucose Fuel: Achieving High Power Output and Enhanced Operational Stability

AbstractAn enzyme‐based biofuel cell (EBFC) is widely regarded as one of the most efficient power sources for bio‐friendly and implantable medical devices, capable of converting electrochemical reactions into electrical currents under physiological conditions. However, despite its potential, the practical and commercial use of EBFCs is limited by their low power output and operational instability. Therefore, significant research efforts have focused on increasing power output and stability by improving electron transfer between enzymes and host electrodes and developing efficient enzyme immobilization techniques. However, most EBFCs produced by current methods still deliver unsatisfactory performance. A promising approach to address these challenges is the use of conductive linkers that promote favorable interfacial interactions between adjacent enzymes and between enzymes and host electrodes. These linkers can facilitate electron transfer and ensure robust enzyme immobilization. In addition, designing the host electrode with a 3D structure and a large surface area can further improve the areal energy performance. This perspective reviews the working principles, types, and electron transfer mechanisms of EBFC electrodes and explores how conductive linkers and 3D host electrodes can enhance the performance of EBFC electrodes. Finally, recent advances in integrating EBFCs into biomedical devices are described.

What Can CISS Teach Us about Electron Transfer?

Electron transfer (eT) processes have garnered the attention of chemists and physicists for more than seven decades, and it is commonly believed that the essential features of the electron transfer mechanism are well understood─despite some open questions relating to the efficiency of long-range eT in some systems and temperature effects that are difficult to reconcile with the existing theories. The chiral induced spin selectivity (CISS) effect, which has been studied experimentally since 1999, demonstrates that eT through chiral systems depends on the electron's spin. Attempts to explain the CISS effect by adding spin-orbit coupling to the existing eT theories fails to reproduce the experimental results quantitatively, and it has become evident that the theory for explaining CISS must consider electron-vibration and/or electron-electron interactions. In this Perspective we identify some features of the CISS effect that imply that we should reconsider and refine the Marcus-Levich-Jortner mechanistic description for eT processes, especially for nonlinear systems and in the case of long-range eT.

Antioxidant activity of extracts of oregano and marsh cinquefoil, growing in the Altai region, in connection with their content of favonoids

Drugs based on medicinal plants have such advantages over synthetic analogues as low toxicity, better tolerability and reduced risk of addiction. Antioxidant agents in medicinal plants include substances from the flavonoid group, due to their ability to inactivate free radical processes, due to the mechanism of electron transfer between reaction components to neutralize free radicals. Among the medicinal plants of Western Siberia and the Altai Territory, oregano and marsh cinquefoil have a high content of flavonoids. The purpose of the study was to evaluate the antioxidant activity of alcohol-free extracts of oregano and marsh cinquefoil growing in the Altai region in connection with the content of flavonoids (flavonols and proanthocyanidins). To conduct the study, alcohol-free extracts of the studied plants were prepared using patented technology. The content of flavonols and proanthocyanidins was studied by arbitration techniques using spectrophotometry. The antioxidant activity of the extracts was measured using cathodic voltammetry method. The results showed that the average flavonol content in oregano extract was 866.5 μg/ml, while only traces were found in the extract of cinquefoil (60.0 μg/ ml). The average content of proanthocyanidins in the extract of cinquefoil was 4.05%, in the extract of oregano content of proanthocyanidins was 0.43%. The average coefficient of antioxidant activity for cinquefoil extract was 11.63 mmol/l×min and 3.81 mmol/l×min for oregano extract. From the results obtained, we can conclude that it is advisable to use extracts of marsh cinquefoil and oregano, growing in the Altai Territory, in the composition of biologically active antioxidant additives.

Photocatalytic fuel cell based on dual Z-scheme heterojunction photoanode InVO4/g-C3N4/Bi2WO6/Ti for efficient Rhodamine B degradation and power generation

Finding suitable semiconductor materials to construct efficient photoanode is the key to improve PFC performance. In this paper, InVO4/g-C3N4/Bi2WO6/Ti composite photoanode was prepared and assembled with Cu cathode to construct PFC for rhodamine B (RhB) degradation and power generation. The InVO4/g-C3N4/Bi2WO6/Ti photoanode was characterized by XRD, FT-IR, XPS, SEM, TEM, EDS and DRS. The electrochemical properties of the PFC including polarization curves, power density, transient photocurrent, LSV and CV curves were analyzed to explore its power generation and electron transfer mechanism. The results showed that the ternary composite photoanode had stronger light absorption, smaller Eg (1.96 eV) and Rct (0.71 Ω), and higher photocurrent current density (0.16 mA cm−2) than binary and single composite photoanodes, indicating that it had higher utilization rate of excitation light energy and carrier mobility. The RhB degradation rate, Pmax, Jsc and Voc of PFC were 93.1 % (90 min), 18.02 µW cm−2, 0.223 mA cm−2 and 0.44 V, respectively. Further mechanistic studies show that the PFC has good photoexcited carrier separation and strong redox capacity due to double Z-scheme heterojunction between Bi2WO6 and InVO4 and between Bi2WO6 and g-C3N4, so as to generate more O2− and h+ to degrade RhB through N-deethylation, dealkylation and ring opening reactions. This study provides a practical approach for the development of high-efficiency double Z-scheme composite photoanode.

Z-scheme heterojunction TNCoPc/BiOBr nanomicrospheres for efficient photodegradation of tetracycline and rhodamine B: Degradation performance, intrinsic mechanism and degradation pathway studies

The natural ecosystem has been significantly jeopardized due to the misuse of organic dyes and antibiotics. To treat organic wastewater safely and efficiently, this study synthesized a binary composite photocatalyst TNCoPc/BiOBr, using a solvothermal method that involved loading cobalt tetranitro phthalocyanine onto BiOBr. The results of the catalytic performance tests indicated that the composites exhibited the capacity to degrade rhodamine B and tetracycline hydrochloride by 97.75 % and 78.37 %, respectively. Moreover, the composite exhibited good cyclic stability. Subsequent analytical characterization confirmed the formation of a Z-scheme heterojunction, resulting in a synergistic effect. This Z-scheme heterojunction facilitated the capacity of photocatalyst to achieve enhanced light absorption, augmented photogenerated carrier separation efficiency, and augmented redox capacity. Additionally, theoretical calculations were employed to further elucidate the catalytic mechanism and synergistic effects. The results demonstrate that the Co-N4 sites are the active center of the TNCoPc and verify the contribution of nitro substitution to the photogenerated electron transfer mechanism on TNCoPc. Furthermore, a systematic degradation pathway was predicted and deduced based on Fukui indices and liquid chromatography-mass spectrometry data. This study presents a paradigm for the application of composite photocatalysts containing substituted phthalocyanines in the degradation of organic wastewater.

The Role of a Redox‐Active Ligand in Cu(II)‐Nitrenoid Formation and Its Aziridination Reactivity

AbstractMetal‐nitrenoid species are the key intermediate in nitrene transfer reactions. The bond formation between the open‐shell transition metal and the nitrene species dictates their overall reactivity. Herein, we present an in‐depth electronic structure investigation to uncover how the formation of a Cu(II)‐nitrenoid species is assisted by redox‐active iminosemiquinone (ISQ) ligand in the [CuII(LISQ)2] complex and impacts the nitrene transfer reactivity. The reaction energetics of the aziridination reaction between N‐tosyliminophenyliodinane and 4‐chlorostyrene is established by DFT calculations, where the formation of the Cu(II)‐nitrenoid intermediate (Int1) is found to be the rate‐determining step. Based on the natural orbital and spin populations obtained from the ab initio multiconfigurational CASSCF(13,13) calculation, the electronic nature of the elusive Cu(II)‐nitrenoid intermediate (Int1) could be formulated as “imidyl” [(LISQ)(LIBQ)CuII─•NTos] (Tos = Tosyl) species. A weak σ interaction between the Cu(II) center and the N‐atom of the nitrene moiety (Cu 20% + N 29%) involving a Cu─N distance of 1.92 Å defines the Cu‐nitrenoid bonding. The interplay between elongated Cu─N bond and high‐spin population on N‐atom (+0.96) corroborates its high nitrene transfer ability. Furthermore, the intrinsic bond orbital (IBO) analysis unravels a ligand‐to‐substrate electron transfer mechanism that facilitates the formation of the crucial Cu(II)‐nitrenoid species.

Modification Orbital Electronic States in Nickel-Based Hydroxides Via Cobalt/Iron Co-Doping for High-Efficiency Methanol Electrooxidation.

The nickel hydroxide-based (Ni(OH)2) methanol-to-formate electrooxidation reaction (MOR) performance is greatly related to the orbital electronic states. Hence, optimizing the orbital electronic states to achieve enhanced MOR activities are highly desired. Here, cobalt (Co) and iron (Fe) doping are used to modify the orbital electronic states. Although both dopants can broaden the orbital; however, Co doping leads to an elevation in the energy level of highest occupied crystal orbital (HOCO), whereas Fe doping results in its reduction. Such a discrepancy in the regulation of orbital electronic states stems from the disparate partial electron transfer mechanisms amongst these transition metal ions, which possess distinct energy level and occupancy of d orbitals. Motivated by this finding, the NiCoFe hydroxide is prepared and exhibited an excellent MOR performance. The results showed that the Co dopants effectively suppress the partial electron transfer from Ni to Fe, combined with the orbital broadening induced by NiO6 octahedra distortion, endowing NiCoFe hydroxide with high HOCO and broad orbital. It is believed that the work gives an in-depth understanding on orbital electronic states regulation in Ni(OH)2, which is beneficial for designing Ni(OH)2-based catalysts with high MOR performance.

Highly selective photocatalytic oxidation of CH4 to CH3OH: A theoretical study

Photooxidation of methane (CH4) in aqueous solution to generate high-value organic compounds is an effective way to replace traditional industrial methods. It is crucial to select catalysts that can avoid competitive reactions and achieve high selectivity. Using first principles calculations, a novel one-dimensional (1D) Ti3C2O2 nanoribbon (NR)/two-dimensional (2D) monolayer MoS2 (MS) heterojunction photocatalyst was ingenious designed in this work, which can achieve the oxidation of CH4 molecules and suppress the execution of competitive reactions. The results indicate that the constructed 1D NR exhibits semiconductor properties and its energy level position meet the requirements of photocatalytic oxidation for CH4. The heterojunction structure composed of NR and MS forms an efficient S-Scheme electron transfer mechanism under illumination, which not only provides sufficient internal driving force for CH4 oxidation, but also effectively avoids the competitive reaction between water molecules and photo-generated holes. Specifically, the photocatalysts exhibits high selectivity and low reaction overpotential for the generation of methanol (CH3OH). This study provides a new perspective for photocatalytic CH4 oxidation and demonstrates the potential application value of 1D MXene in the future field of photocatalysis.

Synergetic effect of pyrrhotite and zero-valent iron on Hg(Ⅱ) removal in constructed wetland: Mechanisms of electron transfer and microbial reaction

Effective removal of mercury (Hg) from wastewater is significant due to its high toxicity, especially methylmercury (MeHg). Reducing of Hg(II) to Hg(0) in constructed wetlands (CWs) using iron-based materials is an effective strategy for preventing the formation of MeHg. However, the surface passivation of zero-valent iron (ZVI) limits its application. Herein, synergetic ZVI and pyrrhotite were utilized to enhance Hg removal in CWs. Results indicated that the removal of total Hg, dissolved Hg, and particulate Hg in CWs with ZVI and pyrrhotite were improved by 21.68 ± 0.76 %, 13.02 ± 0.88 %, and 22.27 ± 0.76 % compared to that with single ZVI or pyrrhotite. Pyrrhotite increased the surface corrosion of ZVI, thereby facilitating the process of iron reduction. The redox of iron promoted the generation of EPS, which could provide electrons for Hg(II) reduction. The sulfur also participates in electron transfer by driving the methylation of Hg and provides sulfides to form FeS-Hg complexes and HgS precipitation. The abundance of key enzymes that involved in iron reduction and Hg transformation was enhanced with the addition of ZVI and pyrrhotite. The synergetic of pyrrhotite and ZVI enhances the removal of Hg in CW, offering a promising technology for high-efficiency treatment of Hg.