Electron Transfer Mediator Research Articles

LDH-Based Voltammetric Sensors

Layered double hydroxides (LDHs), also named hydrotalcite-like compounds, are anionic clays with a lamellar structure which have been extensively used in the last two decades as electrode modifiers for the design of electrochemical sensors. These materials can be classified into LDHs containing or not containing redox-active centers. In the former case, a transition metal cation undergoing a reversible redox reaction within a proper potential window is present in the layers, and, therefore, it can act as electron transfer mediator, and electrocatalyze the oxidation of an analyte for which the required overpotential is too high. In the latter case, a negatively charged species acting as a redox mediator can be introduced into the interlayer spaces after exchanging the anion coming from the synthesis, and, again, the material can display electrocatalytic properties. Alternatively, due to the large specific surface area of LDHs, molecules with electroactivity can be adsorbed on their surface. In this review, the most significant electroanalytical applications of LDHs as electrode modifiers for the development of voltammetric sensors are presented, grouping them based on the two types of materials.

Biochar alters the selectivity of MnFe2O4-activated periodate process through serving as the electron-transfer mediator

Constructing green and sustainable advanced oxidation processes (AOPs) for the degradation of organic contaminants is of great importance but still remains big challenge. In this work, an effective AOP (MnFe2O4-activated periodate, MnFe2O4/PI) was established and investigated for the oxidation of organic contaminants. To avoid the severe aggregation of MnFe2O4 nanoparticles, a hybrid MnFe2O4-biochar catalyst (MnFe2O4-BC) was further synthesized by anchoring MnFe2O4 nanoparticles on chemically inert biochar substrate. Intriguingly, MnFe2O4-BC/PI exhibited different selectivity towards organic contaminants compared with MnFe2O4/PI, revealing that biochar not only served as the substrate, but also directly participated into the oxidation process. Electron-transfer mechanism was comprehensively elucidated to be responsible for the abatement of pollutants in both MnFe2O4/PI and MnFe2O4-BC/PI. The surface oxygen vacancies (OVs) of MnFe2O4 were identified as the active sites for the formation of high potential complexes MnFe2O4-PI*, which could directly and indirectly degrade the organic pollutants. For the hybrid MnFe2O4-BC catalyst, biochar played multiple roles: (i) substrate, (ii) provided massive adsorption sites, (iii) electron-transfer mediator. The differences in selectivity of MnFe2O4/PI and MnFe2O4-BC/PI were determined by the adsorption affinity between biochar substrate and organics. Overall, the findings of this study expand the knowledge on the selectivity of PI-triggered AOPs.

Exposure of polyethylene microplastics affects sulfur migration and transformation in anaerobic system

Polyethylene (PE) microplastic, which is detected in various environmental media worldwide, also inevitably enters wastewater treatment plants, which may have an impact on anaerobic processes in wastewater treatment. In this work, the effect of PE microplastics on anaerobic sulfur transformation was explored. Experimental results showed that PE microplastics addition at 0.1%− 0.5% w/w promoted H2S production by 14.8%−27.4%. PE microplastics enhanced the release of soluble organic sulfur and inorganic sulfate, and promoted the bioprocesses of organosulfur compounds hydrolysis and sulfate reduction. Mechanism analysis showed that PE microplastics increased the content of electroactive components (e.g., protein and humic acids) contained in extracellular polymeric substances (EPS). In particular, PE microplastics increased the proportion and the dipole moment of α-helix, an important component involved in electron transfer contained in extracelluar protein, which provided more electron transfer sites and promoted the α-helix mediated electron transfer. These enhanced the direct electron transfer ability of EPSs, which might explain why PE microplastics facilitated the bioprocesses of organosulfur compounds hydrolysis and sulfate reduction. Correspondingly, metagenomic analysis revealed that PE microplastics increased the relative abundance of S2- producers (e.g., Desulfobacula and Desulfonema) and the relative abundance of functional genes involved in anaerobic sulfur transformation (e.g., PepD and cysD), which were beneficial to H2S production in anaerobic system.

Electron transfer-mediated peroxymonosulfate activation through monoatomic Fe–pyridinic N4 moiety in biochar-based catalyst for electron-rich pollutants degradation in groundwater

Pollution of groundwater by electron-rich refractory organic pollutants (e-ROPs) is detrimental to ecological integrity and human health. Biochar (BC)-based single-atom Fe catalysts (Fe–SACs) triggering nonradical peroxymonosulfate (PMS) process has shown great potential in addressing this problem. Nevertheless, the successful formation and precise regulation of active sites on BC remain formidable challenges. Herein, co-pyrolysis of BC derived from shrimp shells and N-containing supramolecular organic frameworks with a hexagonal cavity structure of Fe3+–N3 (Fe–SOFs) was, for the first time, used to prepare an efficient and inexpensive BC-based Fe–SAC (Fe–MCA@SS). The Fe–N bond was successfully grafted from Fe–SOFs onto BC and subsequently transformed into monoatomic Fe–pyridinic N4. Moreover, Fe–MCA@SS successfully triggered an efficient nonradical PMS process, degrading 94.5 % of aniline (AN) within 5 min. Mediated electron transfer (MET) mechanism was primarily responsible for AN removal. MET was attributed to the following factors: the synergistic effect of the stronger chemical adsorption of PMS with an Fe atom in Fe–pyridinic N4 active sites, the higher redox potential of [Fe–MCA@SS/PMS]*, and the value of the lowest unoccupied molecular orbital of AN being larger than the value of highest occupied molecular orbital of [Fe–MCA@SS/PMS]*. This study sheds new light on the preparation of BC-based SACs catalyst with efficient nonradical oxidation ability and an excellent feasibility to remove electron-rich organic pollutants in groundwater.

Dual role of pyrogenic carbon in mediating electron transfer from clay minerals to chromium in aqueous and solid media

Clay minerals (CMs) and pyrogenic carbons (PCs) often co-exist in the environment and participate in the redox cycling of pollutants. This study unveiled the dual role of PCs in CM-dominated chromium transformation in both aqueous and agar solidification media. The findings showed that CMs and PCs adsorbed minimal Cr(VI), while reduced CMs and PCs displayed a substantial difference by directly reducing Cr(VI) to solid/dissolved Cr(III) through reactive structural Fe(II) and functional groups, respectively. Moreover, dissolved PCs were found to mediate electron transfer from reduced CMs to Cr(VI) in aqueous and solid media. Interestingly, the effect of solid PCs on Cr(VI) reduction by reduced CMs was concentration-dependent. At lower concentrations, solid PCs dispersed reduced CMs, acting as electron mediators and facilitating both direct and indirect Cr(VI) reduction, resulting in solid Cr(III) rather than dissolved Cr(III). Conversely, at higher concentrations, solid PCs served as redox buffers, storing electrons transferred from reduced CMs to Cr(VI). In either case, the transformed chromium was primarily immobilized on the surface of CMs rather than PCs. These findings offer valuable insights into pollutant transformations associated with CMs and PCs, deepening our understanding of their geochemical processes. Environmental ImplicationThe natural transformation of chromium (Cr), a ubiquitous environmental pollutant, is intricately linked to redox-active species like clay minerals (CMs) and pyrogenic carbon (PC). In this pioneering study, we explored the impact of the interaction between CMs and PCs on the transformation of Cr in both aqueous and solid systems. Our discoveries offer valuable insights into the dynamics of Cr associated with varying concentrations of natural redox-active species across diverse environmental settings.

Advancing autotrophic nitrogen removal in low C/N ratio wastewater: Innovative application of supercapacitor to enhance microbial electrolysis cells

This study presents a novel approach, the Supercapacitor Microbial Electrolysis Cell (SC-MEC), which utilizes a supercapacitor as an external power source to enhance the efficiency of autotrophic nitrogen removal in low C/N ratio wastewater. The results demonstrated that the SC-MEC system, operating under anaerobic conditions and devoid of any organic carbon source, exhibited exceptional performance in ammonia oxidation and total nitrogen (TN) removal when solely relying on ammonia nitrogen as the electron donor. Operating at a voltage of 1.8 V with a capacitance capacity of 30 F, ammonium oxidation rated up to 56.51 mg/L/day and TN removal rated up to 54.64 mg/L/day, in which 97% of ammonium nitrogen was converted to gaseous nitrogen. Furthermore, the charging and discharging process of supercapacitors autonomously regulated the bipolar potentials. Cyclic voltammetry (CV) analysis showed the significantly enhanced electrochemical activity of the SC-MEC system during the reaction process. Based on in-situ CV test results, it was inferred that this enhancement was associated with extracellular electron transfer mediators. The microbial community analysis revealed a process of synchronous nitrification and denitrification (SND) coupled with anammox, involving multiple genera, such as Candidatus Kuenenia, Nitrosomonas, Truepera, and Bosea. In conclusion, this study highlights the tremendous potential of SC-MEC in achieving efficient autotrophic nitrogen removal, offering more feasible and economical solutions for addressing low C/N water pollution issues.

Nonlinear Reaction-Diffusion and Mediated Electron Transfer Process at Conducting Polymer Modified Ultramicroelectrodes

The primary goal of this article is to present novel analytical solutions for the coupled nonlinear equation found in the mediated electron transfer process at polymer-modified conducting ultramicroelectrodes. Taylor’s series method is utilized to obtain approximate analytical solutions for the reaction-diffusion equations, allowing for the determination of the substrate and mediator concentrations and the current response concerning the substrate concentration at the electrode’s surface. The impact of different factors on concentration and current is also explored. The derived analytical results are in strong agreement with numerical results and with other analytical outcomes from the literature.

Crucial roles of soil inherent Fe-bearing minerals in enhanced Cr(VI) reduction by biochar: The electronegativity neutralization and electron transfer mediation

Biochar has been used for soil Cr(VI) remediation in the last decade due to its enriched redox functional groups and good electrochemical properties. However, the role of soil inherent Fe-bearing minerals during the reduction of Cr(VI) has been largely overlooked. In this study, biochar with different electron-donating capacities (EDCs) was produced at 400 °C (BC400) and 700 °C (BC700), and their performance for Cr(VI) reduction in soils with varied properties (e.g., Fe content) was investigated. The addition of BC400 caused around 14.2–36.0 mg g−1 Cr(VI) reduction after two weeks of incubation in red soil, paddy soil, loess soil, and fluvo-aquic soil, while a less Cr(VI) was reduced by BC700 (2.57–16.7 mg g−1) with smaller EDCs. The Cr(VI) reduction by both biochars in different soils was closely related to Fe content (R2 = 0.93–0.98), so red soil with the richest Fe (14.8% > 1.79–3.49%) showed the best reduction capability, and the removal of soil free Fe oxides (e.g., hematite) resulted in 71.9% decrease of Cr(VI) reduction by BC400. On one hand, Fe-bearing minerals could increase the soil acidity, neutralize the surface negative charge of biochar, enhance the contact between Cr(VI) and biochar, and thus facilitate the direct Cr(VI) reduction by biochar in soils. On the other hand, Fe-bearing minerals could also facilitate the indirect Cr(VI) reduction by mediating the electron from biochar to Cr(VI) with the cyclic transformation of Fe(II)/Fe(III). This study demonstrates the key role of soil Fe-bearing minerals in Cr(VI) reduction by biochar, which advances our understanding on the biochar-based remediation mechanism of Cr(VI)-contaminated soils.

An All-In-One Integrating Strategy for Designing Platinum(II)-Based Supramolecular Polymers for Photocatalytic Hydrogen Evolution.

Organic polymer photocatalysts have achieved significant progress in photocatalytic hydrogen evolution, while developing the integrated organic polymers possessing the functions of photosensitizer, electron transfer mediator, and catalyst simultaneously is urgently needed and presents a great challenge. Considering that chalcogenoviologens are able to act as photosensitizers and electron-transfer mediators, a series of chalcogenoviologen-containing platinum(II)-based supramolecular polymers is designed, which exhibited strong visible light-absorbing ability and suitable bandgap for highly efficient photocatalytic hydrogen evolution without the use of a cocatalyst. The hydrogen evolution rate (HER) increases steadily with the decrease in an optical gap of the polymer. Among these "all-in-one" polymers, Se-containing 2D porous polymer exhibited the best photocatalytic performance with a HER of 3.09mmolg-1h-1 under visible light (>420nm) irradiation. Experimental and theoretical calculations reveal that the distinct intramolecular charge transfer characteristics and heteroatom N in terpyridine unit promote charge separation and transfer within the molecules. This work could provide new insights into the design of metallo-supramolecular polymers with finely tuned components for photocatalytic hydrogen evolution from water.

Benchmarking Trisaminocyclopropeniums as Mediators for Anodic Oxidation Reactions.

This report benchmarks a tris(amino)cyclopropenium (TAC) salt as an electron-transfer mediator for anodic oxidation reactions in comparison to two known mediators: a triarylamine and a triarylimidazole derivative. The three mediators have redox potentials, diffusion coefficients, and heterogeneous electron transfer rates similar to those of glassy carbon electrodes in acetonitrile/KPF6. However, they differ significantly in their performance in two electro-organic reactions: anodic fluorination of a dithiane and anodic oxidation of 4-methoxybenzyl alcohol. These differences are rationalized based on variable stability in the presence of reaction components (e.g., NEt3·3HF, lutidine, and Cs2CO3) as well as very different rates of electron transfer with the organic substrate. Overall, this work highlights the advantages and disadvantages of each mediator and provides a foundation for expanding the applications of TACs in electro-organic synthesis moving forward.

In situ growth of iron incorporated Ni3S2 nanosheet on nickel foam in mediating electron transfer to peroxymonosulfate for pollutant abatement

Catalytic oxidation of organic pollutants is a well-known and effective technique for pollutant abatement. Unfortunately, this method is significantly hindered in practical applications by the low efficiency and difficult recovery of the catalysts in a powdery form. Herein, a three-dimensional (3D) framework of Fe-incorporated Ni3S2 nanosheets in-situ grown on Ni foam (Fe-Ni3S2@NF) was fabricated by a facile two-step hydrothermal process and applied to trigger peroxymonosulfate (PMS) oxidation of organic compounds in water. A homogeneous growth environment enabled the uniform and scalable growth of Fe-Ni3S2 nanosheets on the Ni foam. Fe-Ni3S2@NF possessed outstanding activity and durability in activating PMS, as it effectively facilitated electron transfer from organic pollutants to PMS. Fe-Ni3S2@NF initially supplied electrons to PMS, causing the catalyst to undergo oxidation, and subsequently accepted electrons from organic compounds, returning to its initial state. The introduction of Fe into the Ni3S2 lattice enhanced electrical conductivity, promoting mediated electron transfer between PMS and organic compounds. The 3D conductive Ni foam provided an ideal platform for the nucleation and growth of Fe-Ni3S2, accelerating pollutant abatement due to its porous structure and high conductivity. Furthermore, its monolithic nature simplified the catalyst recycling process. A continuous flow packed-bed reactor by encapsulating Fe-Ni3S2@NF catalyst achieved complete pollutant abatement with continuous operation for 240 h, highlighting its immense potential for practical environmental remediation. This study presents a facile synthesis method for creating a novel type of monolithic catalyst with high activity and durability for decontamination through Fenton-like processes.

Properties of the iron-sulfur cluster electron transfer relay in an [FeFe]-hydrogenase that is tuned for H2 oxidation catalysis

[FeFe]-hydrogenases catalyze the reversible oxidation of H2 from electrons and protons at an organometallic active site cofactor named the H-cluster. In addition to the H-cluster, most [FeFe]-hydrogenases possess accessory FeS cluster (F-cluster) relays that function in mediating electron transfer with catalysis. There is significant variation in the structural properties of F-cluster relays amongst the [FeFe]-hydrogenases, however it is unknown how this variation relates to the electronic and thermodynamic properties, and thus the electron transfer properties, of F-cluster relays. Clostridium pasteurianum [FeFe]-hydrogenase II (CpII), exhibits a large catalytic bias for H2 oxidation (compared to H2 production), making it a notable system for examining if F-cluster properties contribute to the overall function and efficiency of the enzyme. By applying a combination of multifrequency and potentiometric EPR, we resolved two EPR signals with distinct power- and temperature-dependent properties at g = 2.058 1.931 1.891 (F2.058) and g = 2.061 1.920 1.887 (F2.061), with assigned midpoint potentials of -140 ± 18 mV and -406 ± 12 mV vs. NHE, respectively. Spectral analysis revealed features consistent with spin-spin coupling between the two [4Fe-4S] F-clusters, and possible functional models are discussed that account for the contribution of coupling to the electron transfer landscape. The results signify the interplay of electronic coupling and free energy properties and parameters of the FeS clusters to the electron transfer mechanism through the relay and provide new insight as to how relays functionally complement the catalytic directionality of active sites to achieve highly efficient catalysis.

Biogenic sulfur recovery from sulfate-laden antibiotic production wastewater using a single-chamber up-flow bioelectrochemical reactor

The high-concentration sulfate (SO42−) in the antibiotic production wastewater hinders the anerobic methanogenic process and also proposes possible environmental risk. In this study, a novel single-chamber up-flow anaerobic bioelectrochemical reactor (UBER) was designed to realize simultaneous SO42− removal and elemental sulfur (S0) recovery. With the carbon felt, the cathode was installed underneath and the anode above to meet the different biological niches for sulfate reducing bacteria (SRB) and sulfur oxidizing bacteria (SOB). The bio-anode UBER (B-UBER) demonstrated a much higher average SO42− removal rate (SRR) of 113.2 ± 5.7 mg SO42−−S L−1 d−1 coupled with a S0 production rate (SPR) of 54.4 ± 5.8 mg S0-S L−1 d−1 at the optimal voltage of 0.8 V than that in the abio-anode UBER (control reactor) (SRR = 86.6 ± 13.4 mg SO42−−S L−1 d−1; SPR = 25.5 ± 9.7 mg S0-S L−1 d−1) under long-term operation. A large amount of biogenic S0 (about 72.2 mg g−1 VSS) was recovered in the B-UBER. The bio-anode, dominated by Thiovirga (SOB genus) and Acinetobacter (electrochemically active bacteria genus), exhibited a higher current density, lower overpotential, and lower internal resistance. C-type cytochromes mainly served as the crucial electron transfer mediator for both direct and indirect electron transfer, so that significantly increasing electron transfer capacity and biogenic S0 recovery. The reaction pathways of the sulfur transformation in the B-UBER were hypothesized that SRB utilized acetate as the main electron donor for SO42− reduction in the cathode zone and SOB transferred electrons to the anode or oxygen to produce biogenic S0 in the anode zone. This study proved a new pathway for biogenic S0 recovery and sulfate removal from sulfate-laden antibiotic production wastewater using a well-designed single-chamber bioelectrochemical reactor.

Bio-inspired MOF nanozyme-engineered biocatalytic precipitation strategy mediates electron transfer for ultrasensitive photoelectrochemical immunoassay

Enzyme-like nanomaterials (nanozyme) has been used to generate amplified response signals in biosensors instead of the bio-enzyme, on account of their higher stability and comparable catalytical activity. Especially the metal-organic framework (MOF) materials with ultra-high porosity and high specific surface area, which is more suitable for deriving superior nanozyme. In order to deal with the increasing demand of healthcare diagnostics and biomedical research, here we propose a novel approach for ultrasensitive photoelectrochemical (PEC) immunoassay. The bio-inspired MOF-derived nanozyme Hemin/BSA@ZIF-8 was introduced into the target biorecognition and sensing processes to accelerate the oxidization of substrate to produce insoluble precipitate, which will impede the electron transfer and lead to a significant reduction in photocurrent. The proposed PEC sensor exhibits a wide linear range of 0.1pgmL−1 ~ 100ngmL−1, and a low detection limit of 11.9 fg mL−1 for cardiac troponin I (cTnI) detection. This work brings a new insight of the bio-inspired MOF nanozyme-mediated PEC immunoassay designing, and offers a novel sensing strategy for accurate human biomarker analysis.

Selective degradation of organic pollutants by highly dispersed Fe, Ni anchored on nitrogen carbon activating persulfate system: Electron transfer promotion, the impact of pollutant redox and adsorption properties

The advanced oxidation processes using persulfate (PS-AOPs) as oxidant is an effective way to remove refractory organic pollutants from environment. Designing activators with higher activation efficiency and stability plays an important role in degradation of organic pollutants via PS-AOPs. Furthermore, redox and adsorption properties of pollutants also affect the selective degradation efficiency. In this study, we synthesized FeNi@CN derived from ZIF-8 in which highly dispersed Fe and Ni were anchored on nitrogen (N) doped carbon (C). The activator exhibited high activation potential and stability for paracetamol (PCT) degradation by activated peroxymonosulfate (PMS). The FeNi@CN/PMS system degraded PCT through electron transfer pathway, and the coordination of Fe-N and Ni-N improved the efficiency of catalyst mediated electron transfer. The abundant pyridinic N provided a large number of sites for PMS complexation. The bimetallic synergistic effect and N doping endowed the excellent comprehensive performance of FeNi@CN. The significant impact of pollutant redox and adsorption properties on degradation efficiency were also studied. It was observed that high half-wave potential (E1/2) and excessive adsorption were not conducive to electron transfer. Multi-parameter linear fitting was performed on the degradation rates of different pollutants using half-wave potential and pseudo first order adsorption rate constants, which showed the good correlation among them. This work not only provided insights into the mechanism and the influence of activator structure on electron transfer in PMS activation, but also proposed a new model to describe the effects of redox and adsorption properties on selective degradation of various category pollutants.

Hierarchical modulation of extracellular electron transfer processes in microbial fuel cell anodes for enhanced power output through improved Geobacter adhesion

Although microbial fuel cell (MFC) technology is nearing practical realization, the challenge of attaining higher power output continues to impede its widespread implementation. In this study, we successfully developed free-standing three-dimensional high-performance anode materials for MFCs using a straightforward "one-step" process based on garlic. The resulting anode not only promotes the accumulation of biomass and the enrichment of exoelectrogen Geobacter but also facilitates interfacial extracellular electron transfer. This led to rapid start-up within just three days, a robust power density of 12.37 W/m3, and an impressive 24.04 % coulombic efficiency in mixed-culture MFC reactors. Our investigation into the underlying mechanisms of exocellular electron transfer revealed improvements in both direct electron transfer and mediated electron transfer processes. Notably, the fabrication of carbonized garlic MFC anodes proves to be technically competitive and economically relevant. It not only paves the way for the development of high-performance MFCs but also provides valuable insights for the rational design of materials related to microbial electrochemical technologies.

Sweat lactate biosensor based on lactate oxidase immobilized with flower-like NiCo2O4 and carbon nanotubes

We design a portable and non-invasive lactate biosensor that can conveniently monitor lactate levels in real human sweat. The proposed biosensor is constructed through the immobilization of lactate oxidase (LOx) and horseradish peroxidase (HRP) on flower-like NiCo2O4 microspheres coupled with single-walled carbon nanotubes (SWCNTs). The synergistic effect between NiCo2O4 microspheres and SWCNTs can increase the conductivity and the active surface area of the electrode. Using ferrocene–methanol (FcMeOH) as the electron transfer mediator in buffer, the developed biosensor can detect lactate in a wide linear range of 0.1 mM to 30 mM with a detection limit of 39.9 µM under optimal conditions. Additionally, the biosensor exhibits excellent selectivity and stability. As proof of concept, the biosensor was applied to monitor lactate level in real human sweat samples, and the results were in good agreement with those obtained by high-performance liquid chromatography (HPLC) analysis. The lactate biosensor is cost effective and can be as a non-invasive alternative to blood analysis, which is suitable for rapid analysis of lactate levels in the fields of fitness, health monitoring and clinical diagnosis.

Photoinduced Radical Borylation of Alkyl Chlorides

AbstractThe traditional method for the preparation of alkylboronic esters involves transition metal catalysis or transition metal‐free methods relying on single electron transfer. Each method relies on the suitable choice of catalyst or electron transfer mediator. In this study, we have developed a new method for the synthesis of alkylboronic esters from alkyl chlorides and diboron(4) compounds, without the need for additional metal or non‐metal catalysts. We discovered that under 400 nm visible light irradiation, alkyl chlorides can be activated in the presence of bis(neopentyl glycolato)diboron and an alkoxide base to form alkyl radical intermediates, which then react with diboron(4) compounds, resulting in high yields of alkylboronic esters. The reaction is applicable to both primary and secondary alkyl chlorides. The simplicity of operation and the broad substrate scope of this method make it practical for the synthesis of valuable alkylboronic ester intermediates.

Efficient roxarsone degradation by low-dose peroxymonosulfate with the activation of recycling iron-base composite material: Critical role of electron transfer

Pollutant degradation via electron transfer based on advanced oxidation processes (AOPs) provides an economical and energy-efficient method for pollution control. In this study, an iron-rich waste, heating pad waste (HPW), was recycled as a raw material, and a strong magnetic catalyst (Fe-HPW) was synthesized at high temperature (900 °C). Results showed that in the constructed Fe-HPW/PMS system, effective roxarsone (ROX) degradation and TOC removal (72.54%) were achieved at a low-dose of oxidant (PMS, 0.05 mM) and catalyst (Fe-HPW, 0.05 g L−1), the ratio of PMS to ROX was only 2.5:1. In addition, the released inorganic arsenic was effectively removed from the solution. The analysis of the experimental results showed that ROX was effectively degraded by forming PMS/catalyst surface complexes (Fe-HPW-PMS*) to mediate electron transfer in the Fe-HPW/PMS system. Besides, this system performed effective ROX degradation over a wide pH range (pH=3–9) and showed high resistance to different water parameters. Overall, this study not only provides a new direction for the recycling application of HPW but also re-emphasizes the neglected nonradical pathway in advanced oxidation processes.

Electroreductive Remote Benzylic C(sp3)-H Arylation of Aliphatic Ethers Using Cyanoarenes for the Synthesis of α-(Hetero)aryl Ethers.

An iodoarene-driven electroreductive remote C(sp3)-H arylation of unsymmetrical 1-(o-iodoaryl)alkyl ethers with cyanoarenes for the site selective synthesis of α-(hetero)aryl ethers is developed. With the introduction of cyanoarenes as both aryl sources and electron transfer mediators, this method includes an iodoarene-driven strategy to enable the regiocontrollable formation of two new bonds, one C(sp2)-H bond, and one C(sp2)-C(sp3) bond, in a single reaction step through the sequence of halogen atom transfer (XAT), hydrogen atom transfer (HAT), radical-radical coupling, and decyanation.