Promote Electron Transfer Research Articles

The Interpretation of Carbon Nanotubes’ Electrochemistry: Electrocatalysis and Mass Transport Regime in the Apparent Promotion of Electron Transfer

Carbon nanotubes (CNTs) are widely used in electrochemical sensors due to their significant impact on the electroanalytical signal. However, there remain significant doubts regarding the origin of the improved electroanalytical response observed in CNT-based sensors, particularly concerning the precise role of CNTs in these systems. In particular, the origin of the electrochemical response is controversial, as it may be due to either electrocatalytic or non-electrocatalytic processes. The latter implies that the electroanalytical response is mainly governed by the mass transport phenomena within the porous CNT layer. This article briefly reviews the several comprehensive models based on the role of porosity (diffusion in a ‘thin-layer’) on the electrochemical behavior as well as on the electrocatalytic properties of CNTs to resolve conflicts arising from misinterpretations of the electroanalytical response of CNT-based sensors. However, even though there are some explanations and conclusions on this topic, they seem to be valuable for specific electroactive species, the type of CNTs and/or electrode architecture, the electrode surface, etc. Accordingly, general theories and conclusions are not yet defined, so different approaches to this topic are still needed, since the main phenomenological effects responsible for the nature of the electrochemical response of the electrodes modified with CNTs need to be determined in a rational way.

Electrolyte Design Using "Porous Water” for High‐purity Carbon Monoxide Electrosynthesis from Dilute Carbon Dioxide

Electrosynthesis of high‐purity carbon monoxide (CO) from captured carbon dioxide (CO₂) remains energy‐intensive due to the unavoidable CO₂ regeneration and post‐purification stages. Here, we propose a direct high‐purity CO electrosynthesis strategy employing an innovative electrolyte, termed porous electrolyte (PE), based on "porous water". Zeolite nanocrystals within PE provide permanent pores in the liquid phase, enabling physical CO₂ adsorption through an intraparticle diffusion model, as demonstrated by molecular dynamics simulations and in‐situ spectral analysis. Captured CO₂ spontaneously desorbs under applied reductive potential, driven by the interfacial CO₂ concentration gradient, and is subsequently reduced electrochemically. The high CO₂ concentration in PE enhances mass transfer, and surface ion exchange between Si–OH groups and K⁺ ions on the zeolite surface generates a stronger interfacial electric field, promoting electron transfer steps. This optimized kinetics for mass and electron transfer confers heightened intrinsic activity toward CO₂ electroreduction. The PE‐based electrolysis system demonstrated superior CO Faradaic efficiency and partial current density compared to the conventional CO₂‐fed system. A circular system using PE and a Ni‐N/C cathode realized continuous production of high‐purity CO (97.0 wt%) from dilute CO2 (15%) and maintained > 90.0 wt% under 150 mA cm‐2, with significantly reduced energy consumption and costs.

Electrolyte Design Using "Porous Water" for High-purity Carbon Monoxide Electrosynthesis from Dilute Carbon Dioxide.

Electrosynthesis of high-purity carbon monoxide (CO) from captured carbon dioxide (CO₂) remains energy-intensive due to the unavoidable CO₂ regeneration and post-purification stages. Here, we propose a direct high-purity CO electrosynthesis strategy employing an innovative electrolyte, termed porous electrolyte (PE), based on "porous water". Zeolite nanocrystals within PE provide permanent pores in the liquid phase, enabling physical CO₂ adsorption through an intraparticle diffusion model, as demonstrated by molecular dynamics simulations and in-situ spectral analysis. Captured CO₂ spontaneously desorbs under applied reductive potential, driven by the interfacial CO₂ concentration gradient, and is subsequently reduced electrochemically. The high CO₂ concentration in PE enhances mass transfer, and surface ion exchange between Si-OH groups and K⁺ ions on the zeolite surface generates a stronger interfacial electric field, promoting electron transfer steps. This optimized kinetics for mass and electron transfer confers heightened intrinsic activity toward CO₂ electroreduction. The PE-based electrolysis system demonstrated superior CO Faradaic efficiency and partial current density compared to the conventional CO₂-fed system. A circular system using PE and a Ni-N/C cathode realized continuous production of high-purity CO (97.0 wt%) from dilute CO2 (15%) and maintained > 90.0 wt% under 150 mA cm-2, with significantly reduced energy consumption and costs.

Impact of carbon-based conductive materials on performance and microbial community composition during anaerobic digestion of butanol-octanol wastewater.

Butanol-octanol wastewater (BOW) from coal syngas conversion with hazardous and high salinity could hinder anaerobic digestion (AD). The carbon-based conductive materials (CCM) appear viable for enhancing the AD capability of BOW. Nevertheless, the potential mechanisms of different CCM types on AD of BOW remain unclear. The three different morphologies of CCM, powdered activated carbon (PAC), granular activated carbon (GAC), and carbon fiber cloth (CFC), were employed to improve methane conversion rate in AD of actual BOW. Results indicated that, compared to other carbon materials, more aromatic functional groups on the surface of GAC promoted electron transfer and notably increased degradation of 3-heptanone in BOW and methanogenic. Microbial community structure analysis showed Geobacter on GAC increased to 30.99%, while Syntrophomonas and Methanosaeta in the sludge increased by 5.05% and 7.7%, respectively. The methane conversion rate of BOW was increased by promoting direct interspecies electron transfer (DIET) through GAC.

Generation of unpaired electrons to promote electron transfer at the cathode of room-temperature sodium sulfur batteries

Generation of unpaired electrons to promote electron transfer at the cathode of room-temperature sodium sulfur batteries

Boosting OER Performance of NiFe‐MOFs via Heterostructure Engineering: Promoted Phase Transformation and Self‐optimized Dynamic Interface Electron Structure

AbstractHow to manipulate heterostructure engineering to achieve high‐efficiency oxygen evolution reaction (OER) remains a significant challenge. Herein, a promising OER heterostructure electrocatalyst with IrNi nanoalloys (≈3.29 ± 0.12 nm) anchored on NiFe‐MOFs (IrNi@NiFe‐MOFs), exhibiting promoted phase transformation and self‐optimized dynamic interface electronic structure, via a one‐step hydrothermal method is designed and developed. Specifically, IrNi@NiFe‐MOFs displays excellent OER performance with a low overpotential of 228 mV at 10 mA cm−2, a small Tafel slope of 37.6 mV dec−1, and robust stability at 10 and 100 mA cm−2. Experimental and theoretical calculations identify the actual active sites as IrNi@NiFeOOH and further reveal that the dynamic structure evolution and self‐optimized dynamic interface electron structure, promoted by heterostructure engineering, boost its OER catalytic performance. Moreover, IrNi@NiFeOOH heterostructure displays strong interface electron interactions and a unique self‐optimized dynamic interface electron structure, resulting in better charge redistribution and adaptive bonding (Ir─O─Ni/Fe bonds). This structure therefore plays a critical role in promoting electron transfer, facilitating the dynamic evolution of reaction intermediates, and reducing the energy barrier of the potential‐determining step, thereby boosting the OER performance. These findings provide new insights into the development of MOF‐based electrocatalysts via heterostructure engineering.

Decreasing the aggregation of photosensitizers to facilitate energy transfer for improved photodynamic therapy.

The mode of energy transfer between photosensitizers and oxygen determines the yield of singlet oxygen (1O2), crucial for photodynamic therapy (PDT). However, the aggregation of photosensitizers promotes electron transfer while inhibiting pure energy transfer, resulting in the generation of the hypotoxic superoxide anion (O2-) and consumption of substantial oxygen. Herein, we achieve the reduction of the aggregation of photosensitizers to inhibit electron transfer through classical chemical crosslinking, thereby boosting the production of 1O2. Specifically, we constructed a cross-linked hydrogel-like nanophotosensitizer (HA-TPP NHs) via amidation reactions between hyaluronic acid (HA) and tetrakis(4-aminophenyl)porphyrin (TATPP). In HA-TPP NHs, porphyrin is anchored at the crosslinking sites, preventing their close proximity. Simultaneously, HA-TPP NHs swell in a physiological environment due to water absorption, further increasing the distance between porphyrin molecules to avoid their aggregation. Compared to porphyrin-hyaluronic acid assembling nanoparticles (HA-TPP NPs), we find that the 1O2 generation efficiency of HA-TPP NHs is elevated by over 80%. Furthermore, leveraging the targeting capabilities of hyaluronic acid, HA-TPP NHs demonstrate a remarkable anticancer effect in in vitro and in vivo experiments. This study offers a novel insight and method for improving the therapeutic efficacy of PDT.

Enhanced Hydrogen Evolution Reaction of a Zn+2-Stabilized Tungstate Electrocatalyst

Due to their diverse properties and functionalities, cost-effective transition metal-based nanomaterials have been rigorously studied for electrochemical applications. Ultrathin nanosheets have been identified as the most effective electrodes for catalyzing water-splitting reactions in both acidic and alkaline environments. Here, we reported ZnWO4, a member of the tungstate family, as an effective electrocatalyst for promoting the electrochemical hydrogen evolution reaction. The Zn+2-stabilized tungstate showed a remarkable cathodic reaction during the water-splitting reaction with low overpotential (136 mV at 10 mA cm−2) and small HER kinetics (Tafel Slope = 75.3 mV dec−1) and long-term cyclic durability. The high-valence tungsten stabilized with divalent Zn+2 promotes electron transfer during the reaction, making it an advanced electrocatalyst for green hydrogen production.

Lanthanide-Porphyrin MOF as a Multifunctional Platform for Detection and Integrated Elimination of Cr(VI) and Ciprofloxacin.

Environmental concerns are driving the development of eco-friendly and effective methods for contaminant monitoring and remediation. In this study, a lanthanide porphyrin-based MOF with dual fluorescence sensing and photocatalytic properties was synthesized and applied for the detection and combined removal of Cr(VI) and ciprofloxacin (CIP). Using different excitation wavelengths, the material exhibited selective detection of Cr(VI) via fluorescence quenching and CIP through fluorescence enhancement. The variation in color intensity of Tb-MOF on 3D EEM spectra enabled simultaneous detection of both contaminants. Additionally, Tb-MOF demonstrated a synergistic removal effect, achieving over 95% removal rates of Cr(VI) and CIP within 90 min, with consistent sensing and catalytic performance across four cycles. Mechanistic investigations revealed that (i) strong coordination between Tb3+ and CIP altered the surface potential of Tb-MOF, enhancing Cr(VI) adsorption; (ii) as an efficient electron acceptor, Cr(VI) promoted electron transfer and its reduction to Cr(III); and (iii) superoxide radicals generated via a type I mechanism played a key role in CIP degradation. This research underscores the potential of Tb-MOF as a multifunctional platform for simultaneous detection and synergistic remediation of mixed pollutants.

Cytochrome P450 electrochemical biosensors transforming in vitro metabolism testing - Opportunities and challenges.

The ability of the living world to flourish in the face of constant exposure to dangerous chemicals depends on the management ability of a widespread group of enzymes known as heme-thiolate monooxygenases or cytochrome P450 superfamily. About three-quarters of all reactions determining the metabolism of endogenous compounds, of those carried in foods, of taken drugs, or even of synthetic chemicals discarded into the environment depend on their catalytic performance. The chromatographic and (photo)luminometric methods routinely used as predictive and analytical tools in laboratories have significant drawbacks ranging from limited shelf-life of reagents, use of synthetic substrates, laborious and tedious procedures for highly sensitive detection. In this review, alternative electrochemical biosensors using the cytochrome P450 enzymes as bio-element are emphasized in their main aspects as well regarding their implementation and usefulness. Despite the various schemes proposed for the implementation, reports on real applications are scant for several reasons, including low reaction rates, broad substrate specificity, uncoupling reactions occurrence, and the need for expensive electron transfer partners to promote electron transfer. Finally, the prospect for future developments is introduced, focusing on integrating miniaturized systems with electrochemical techniques, alongside optimizing enzyme immobilization methods and electrode modifications to improve enzymatic stability and enhance sensor reliability. This progress represents a crucial step towards the creation of portable biosensors that mimic human physiological responses, supporting the precision medicine approach.

Combination of FeII-O Species and Fe-O-Zr Bonds Empowers FeOx Nanoclusters Anchored on UiO-66 Robust H2S-Selective Catalytic Oxidation Performance.

The low sulfur selectivity of Fe-based H2S-selective catalytic oxidation catalysts is still a problem, especially at a high O2 content. This is alleviated here through anchoring FeOx nanoclusters on UiO-66 via the formation of Fe-O-Zr bonds. The introduced FeOx species exist in the form of FeIII and FeII. Therein the FeIII-O species are the predominant active sites for H2S-oxidation. The formed Fe-O-Zr bonds strengthen the redox cycle of FeIII/FeII through promoting electron transfer from Fe to Zr. The FeII-O species can activate molecular oxygen to oxidize H2S into elemental S, which accelerates the formation rate of atomic S, hindering its further oxidation into SO2. The combination of these factors empowers the catalysts, enabling 100% H2S conversion and 98.2% sulfur yield. The catalyst also has satisfactory stability with the sulfur selectivity only decreasing from 98.2% to 91.3% after the reaction going on 50 h. The decreased sulfur selectivity might be caused by the deterioration of pores and the deposition of elemental S on the surface. The former hinders the diffusion of sulfur oligomers timely from pores to the gas phase, while the latter is suspected to capture electrons to promote its further reaction with molecular oxygen.

MIL-100@ZIF-67 Enhanced Microbial Electroreduction of CO2 to Produce CH4 by Promoting Electron Transfer

MIL-100@ZIF-67 Enhanced Microbial Electroreduction of CO₂ to Produce CH₄ by Promoting Electron Transfer

Enhanced Electrocatalytic Hydrogen Peroxide Production via a CuWO4/WO3 Heterojunction with High Selectivity and Stability.

The electrocatalytic conversion of oxygen to hydrogen peroxide offers a promising pathway for sustainable energy production. However, the development of catalysts that are highly active, stable, and cost-effective for hydrogen peroxide synthesis remains a significant challenge. In this study, a novel polyacid-based metal-organic coordination compound (Cu-PW) was synthesized using a hydrothermal approach. Cu-PW served as a precursor to construct a composite electrocatalyst featuring a heterointerface between CuWO4 and WO3 (CuWO4/WO3) through pyrolysis. The CuWO4/WO3 heterojunction exhibits an impressive H2O2 selectivity of 91.84% at 0.5 V, marking a 19.65% improvement compared to the pristine Cu-PW. Furthermore, the CuWO4/WO3 catalyst demonstrates exceptional stability, maintaining continuous operation for 29 h. At 0.1 V, it delivers a hydrogen peroxide yield of 1537.8 mmol g-1 h-1, with a Faraday efficiency (FE) of 85%. Additionally, this catalyst effectively degrades methyl blue, achieving a 95% removal from an aqueous system within 30 min. Theoretical analysis further corroborates the high electroactivity of CuWO4/WO3 heterojunction structure. The Cu-O-W bridge formed during the reaction facilitates interfacial electron transport and enhances the role of the W-O bond in proton adsorption and transfer kinetics. This strong interfacial coupling in CuWO4/WO3 promotes electron transfer and the formation of *OOH intermediates, thereby favoring hydrogen peroxide generation. Hence, the as-prepared CuWO4/WO3 demonstrates great potential as an efficient electrocatalyst for the green synthesis of hydrogen peroxide, exhibiting high efficiency as a two-electron oxygen reduction reaction catalyst. This work offers a new approach for fabricating CuWO4/WO3 electrocatalyst with high electroactivity and selectivity, paving the way for cost-effective and sustainable hydrogen peroxide production, significantly reducing reliance on the conventional anthraquinone process.

Unveiling Oxygen Vacancy Engineering in CoMo‐Based Catalysts for Enhanced Oxygen Evolution Reaction Activity

AbstractOxygen vacancy (VO) engineering is widely regarded as a key strategy for enhancing CoMo‐based catalysts for oxygen evolution reaction (OER) while understanding their formation mechanisms and role in boosting OER activity remains a significant challenge. Herein, a CoMoOx system doped is developed with different 3d‐orbital atoms M (V, Ni, Zn, and Mn) to investigate the construction and stabilization of VO and its crucial role in OER performance. In situ and ex situ measurements along with theoretical calculations demonstrate that V doping adjusts the bandgap between the CoMo‐d and O‐p orbitals, leading to the transfer of electrons from the O‐p orbitals to the M‐d orbitals, thereby promoting the formation of VO. The formation of VO leads to an upshifted d‐band center, optimizing the desorption of oxygen intermediates on VO‐CoMoVOx and lowering the energy barrier of the rate‐determining step (RDS), thereby enhancing the catalyst's activity. Additionally, V doping promotes electron transfer from Co to V atoms, stabilizing the VO and ultimately improving the catalyst's stability. The resulting VO ‐CoMoVOx catalyst delivered attractive activity (overpotential of 248 mV at 10 mA cm−2) and durability over 600 h. This study offers a rational method for designing efficient OER electrocatalysts.

CO₂-enhanced methane production by integration of bamboo biochar during anaerobic co-digestion

This study investigates the enhancement of methane production in anaerobic co-digestion (AcoD) through the introduction of exogenous CO₂ and the application of bamboo biochar. Exogenous CO₂ boosts biogas yield by providing an additional carbon source, which requires optimized solubility and pH buffering to ensure effective methanation. Biochar serves as an electron shuttle and pH stabilizer, facilitating CO2 solubility and syntrophic interactions that enhance microbial stability. When combined, biochar and CO₂ (R2) achieved a significant synergistic effect, increasing specific methane production (SMP) by 42.56% compared to the control (R0). Independent additions of biochar (R1) and CO₂ (R3) also improved SMP, with increases of 35.50% and 28.01%, respectively. This enhancement is likely due to the elevated activity of homoacetogenic bacteria and hydrogenotrophic methanogens, with increased acsB gene expression 2.4-fold with biochar+CO₂ and 1.5-fold with CO₂ alone compared to the control. Additionally, biochar facilitated syntrophic metabolism mediated by Cytochrome-C, promoting electron transfer. The study also demonstrated that biochar and CO2 could enhance enzyme activity, including acetyl-CoA synthase, mhpF, and mhpE. Such improvements bolster AcoD efficiency and promote resource recycling within the circular economy framework.

Increasing Lewis acidic sites and promoting electron transfer of Mn2O3 by C-hybridization to improve the peroxymonosulfate activation for Bisphenol A degradation.

The surface acidity and electron transfer performance of manganese oxide catalysts significantly affected its performance of peroxymonosulfate (PMS) activation. In this work, Mn2O3 catalyst was prepared by the precipitation method. The C-hybridization Mn2O3-D (Mn2O3-D) catalyst prepared with disodium oxalate as a precipitant had more Mn3+ and Lewis acid sites on the surface, promoting the binding of PMS on the catalyst surface, which exhibited the best performance in inducing PMS activation to degrade bisphenol A (BPA). Quenching experiments and in situ electron spin resonance (ESR) results indicated that radicals and singlet oxygen were not the main reactive oxygen species (ROSs) in the advanced oxidation process. The chemical probe experiment of phenylmethylsulfone (PMSO) showed that the ≡Mn-OOSO3- metastable intermediate formed by the binding of PMS with Mn sites on the catalyst surface was important active species for contaminants degradation. Contaminants combined with intermediates on the catalyst surface to form the electron transfer channels, which were directly degraded through oxygen-atom-transfer pathway and single-electron-transfer pathway. And the hybridization of C promoted the electron transfer during this process. This work further elucidated the reaction mechanism of PMS activation by manganese oxides, and proposed new ideas for the design of MnOx catalysts for efficient activation of PMS.

Enhanced methanogenesis and efficient ciprofloxacin degradation via nZVI@LDH in an electricity-driven anaerobic bioreactor: A biotic-abiotic hybrid system for ROS regulation and ARGs mitigation.

The escalating presence of antibiotic contaminants in wastewater presents substantial environmental and public health challenges, primarily due to their role in the proliferation of antibiotic resistance genes (ARGs). This study examines the effectiveness of a hybrid system integrating nano zerovalent iron (nZVI) and layered double hydroxides (LDH) in treating wastewater contaminated with ciprofloxacin (CIP). Reactor experiments revealed that incorporating nZVI@LDH mitigated the shock caused by CIP while sustaining a methane production rate that was 116 % higher than that of the control group. Furthermore, there was a 50 % increase in CIP removal efficiency. Notably, there was a significant enrichment of hydrogenotrophic methanogens, such as Methanobacterium and Methanolinea, in the nZVI@LDH-enhanced reactors. Additionally, the levels of reactive oxygen species decreased by 50 %, from 11,813 ± 1230 to 4525 ± 1030 counts/s, and the abundance of ARGs declined by 75-88 % compared to the control reactors. An external electric field further promoted electron transfer, boosting the relative abundance of electrochemically active bacteria, with Proteobacteria comprising up to 40 % of the microbial community in the 1 V + nZVI@LDH reactor. This hybrid system demonstrates significant efficacy in degrading CIP and decreasing ARGs generation, underscoring its potential as a sustainable strategy for managing antibiotic-laden wastewater.

Synthesis of core–shell structured Cu2O@Co(OH)2 anchored on three-dimensional macroporous carbon for efficient non-enzymatic glucose detection

Transition metal oxides and hydroxides have gained significant attention from researchers due to their abundance, low cost, and stable chemical properties. In this study, a straightforward and efficient method was used to anchor Cu2O onto a three-dimensional macroporous carbon (MPC) framework. The Cu2O/MPC template was then etched, allowing for the growth of a cobalt hydroxide layer on the surface of Cu2O nanocubes. The resulting Cu2O@Co(OH)2/MPC composite provides a conductive carbon skeleton that promotes electron transfer, while its core–shell structure increases the specific surface area, enhancing the material’s electrocatalytic activity. The sensor demonstrates a broad linear range (0.3 to 1937.3 μM), high sensitivity (0.776 μA mM−1 cm−2), and a low limit of detection (0.124 μM), offering a promising new approach for non-enzymatic glucose detection. This work contributes to the development of a simple and highly sensitive non-enzymatic glucose sensor.

Biochar-supported MnFeO2 for heterogeneous photo-Fenton degradation of doxycycline: Collaborative promotion of electron transfer and H2O2 activation

Biochar-supported MnFeO2 for heterogeneous photo-Fenton degradation of doxycycline: Collaborative promotion of electron transfer and H2O2 activation

Built-in electric field guides oxygen evolution electrocatalyst reconstruction.

Creating a built-in electric field (BIEF) in catalysts represents an effective strategy to promote electron transfer and induce asymmetric charge distribution, thereby facilitating surface dynamic reconstruction under oxygen evolution reaction (OER) conditions. This review summarizes recent advancements in the field of OER electrocatalysts, with a focus on regulating the work function of components to tailor the BIEFs to guide surface reconstruction processes. It also discusses the importance of surface reconstruction in improving electrocatalytic performance and the influence of BIEFs on the reconstruction of catalysts. By analyzing various strategies for manipulating electric fields for guiding surface reconstruction of OER electrocatalysts, along with numerous representative examples, this review highlights how these techniques can enhance catalytic activity and stability. The findings underscore the potential of engineered BIEFs as a powerful tool in the design of next-generation electrocatalysts, paving the way for more efficient energy conversion technologies.