Anodic Current Research Articles

Sulfite-Assisted Acetate Conversion from CO Electroreduction.

The efficient acetate conversion from CO electroreduction is challenging due to the poor selectivity at high reaction rate, which requires the competition with H2 and other C2+ (i.e., ethylene, ethanol, n-propanol) reduction products. Electrolyte engineering is one of the efficient strategies to regulate the reaction microenvironment. In this work, the adding of sulfite (SO32-) with high nucleophilicity in KOH electrolytes was demonstrated to enable improving the CO-to-acetate conversion via generating a S-O chemical bond between SO32- and oxygenated *C2 intermediates (i.e., *CO-CO, *CO-COH) compared with that in pure KOH system on both synthesized Cu(200)- and normal commercial Cu(111)-facets-exposed metallic Cu catalysts. As a result, the prepared Cu(200)-facets-exposed metallic Cu catalyst with surface ions modification showed an superior Faradaic efficiency of 63.6% at -0.6 A·cm-2, and extraordinary absolute value of peak partial current density as high as 1.52 A·cm-2 with adding SO32- in KOH electrolytes, compared to the best reported values in both CO and CO2 electroreduction. Our work suggests an attractive strategy to introduce the oxyanion with high nucleophilicity in electrolytes to regulate the microenvironment for industrial-current-density electrosynthesis of acetate from CO electroreduction.

Br, O‐Modified Cu(111) Interface Promotes CO2 Reduction to Multicarbon Products

AbstractElectrochemical reduction of CO2 to multicarbon (C2+) products with added value represents a promising strategy for achieving a carbon‐neutral economy. Precise manipulation of the catalytic interface is imperative to control the catalytic selectivity, particularly toward C2+ products. In this study, a unique Cu/UIO‐Br interface is designed, wherein the Cu(111) plane is co‐modified simultaneously by Br and O from UIO‐66‐Br support. Such Cu/UIO‐Br catalytic interface demonstrates a superior Faradaic efficiency of ≈53% for C2+ products (ethanol/ethylene) and the C2+ partial current density reached 24.3 mA cm−2 in an H‐cell electrolyzer. The kinetic isotopic effect test, in situ attenuated total reflection Fourier transform infrared spectroscopy and density functional theory calculations have been conducted to elucidate the catalytic mechanism. The Br, O co‐modification on the Cu(111) interface enhanced the adsorption of CO2 species. The hydrogen‐bond effect from the doped Br atom regulated the kinetic processes of *H species in CO2RR and promoted the formation of *COH intermediate. The formed *COH facilitates the *CO–*COH coupling and promotes the C2+ selectivity finally. This comprehensive investigation not only provides an in‐depth study and understanding of the catalytic process but also offers a promising strategy for designing efficient Cu‐based catalysts with exceptional C2+ products.

Active Oxygenated Structure‐Intensified CO2 Capture Enables Efficient Electrochemical Ethylene Production Over Carbon Nanofibers

AbstractThe pursuit of high efficacy C−C coupling during the electrochemical CO2 reduction reaction remains a tremendous challenge owing to the high energy barrier of CO2 activation and insufficient coverage of the desired intermediates on catalytic sites. Inspired by the concept of capture‐coupled CO2 activation, we fabricated quinone‐grafted carbon nanofibers via an in situ oxidative carbonylation strategy. The quinone functionality of carbon nanofibers promotes the capture of CO2 followed by activation. At a current density of 400 mA cm−2, the Faradaic efficiency of ethylene reached 62.9 %, and a partial current density of 295 mA cm−2 was achieved on the quinone‐rich carbon nanofibers. The results of in situ spectroscopy and theoretical calculations indicated that the remarkable selectivity enhancement in ethylene originates from the quinone structure, rather than the electronic properties of Cu particles. The interaction of quinone with CO2 increases the local *CO coverage and simultaneously hinders the co‐adsorption of *H on Cu sites, which greatly reduces the energy barrier for C−C coupling and restrains subsequent *CO protonation. The modulation strategy involving specific oxygenated structure, as an independent degree of freedom, guides the design of functionalized carbon materials for tailoring the selectivity of desired products during the CO2 capture and reduction.

Active Oxygenated Structure-Intensified CO2 Capture Enables Efficient Electrochemical Ethylene Production Over Carbon Nanofibers.

The pursuit of high efficacy C-C coupling during the electrochemical CO2 reduction reaction remains a tremendous challenge owing to the high energy barrier of CO2 activation and insufficient coverage of the desired intermediates on catalytic sites. Inspired by the concept of capture-coupled CO2 activation, we fabricated quinone-grafted carbon nanofibers via an in situ oxidative carbonylation strategy. The quinone functionality of carbon nanofibers promotes the capture of CO2 followed by activation. At a current density of 400 mA cm-2, the Faradaic efficiency of ethylene reached 62.9 %, and a partial current density of 295 mA cm-2 was achieved on the quinone-rich carbon nanofibers. The results of in situ spectroscopy and theoretical calculations indicated that the remarkable selectivity enhancement in ethylene originates from the quinone structure, rather than the electronic properties of Cu particles. The interaction of quinone with CO2 increases the local *CO coverage and simultaneously hinders the co-adsorption of *H on Cu sites, which greatly reduces the energy barrier for C-C coupling and restrains subsequent *CO protonation. The modulation strategy involving specific oxygenated structure, as an independent degree of freedom, guides the design of functionalized carbon materials for tailoring the selectivity of desired products during the CO2 capture and reduction.

Modulating the Hydrogenation Mechanism of Electrochemical CO2 Reduction Using Ruthenium Atomic Species on Bismuth

AbstractThe conversion of CO2 into formate through electrochemical methods is emerging as an elegant approach for industrial‐scale CO2 utilization in the near future. Although Bismuth (Bi)‐based materials have shown promise thank to their excellent selectivity, their limited reactivity remains a challenge. Herein, this study demonstrates a significant enhancement in the CO2‐to‐formate efficiency of Bi by incorporating ruthenium (Ru) atomic species. Ru single atom doped Bi exhibited a nearly twofold higher partial current density compared with pure Bi and Ru clusters doped Bi, while over 95% Faradaic efficiency (FE) is maintained. Through comprehensive investigations using a combined approach of electrochemical techniques, operando spectroscopy, and theoretical calculations, this study elucidates that the presence of Ru single atom promotes H2O dissociation and H* migration to Bi sites for CO2‐to‐formate conversion by significantly reducing the energy barrier via a H* spillover path. Besides, it is constructed Ru–Bi bridge sites for efficient CO2 hydrogenation via a non‐spillover path, which served as the major mechanism for CO2‐to‐formate conversion in Ru single atom doped Bi.

Reduced Graphene Oxide-Supported SrV4O9 Microflowers with Enhanced Electrochemical Performance for Sodium-Ion Batteries.

Sodium-ion batteries (SIBs) have received considerable attention in recent years. Anode material is one of the key factors that determine SIBs' electrochemical performance. Current commercial hard carbon anode shows poor rate performance, which greatly limits applications of SIBs. In this study, a novel vanadium-based material, SrV4O9, was proposed as an anode for SIBs, and its Na+ storage properties were studied for the first time. To enhance the electrical conductivity of SrV4O9 material, a microflower structure was designed and reduced graphene oxide (rGO) was introduced as a host to support SrV4O9 microflowers. The microflower structure effectively reduced electron diffusion distance, thus enhancing the electrical conductivity of the SrV4O9 material. The rGO showed excellent flexibility and electrical conductivity, which effectively improved the cycling life and rate performance of the SrV4O9 composite material. As a result, the SrV4O9@rGO composite showed excellent electrochemical performance (a stable capacity of 273.4 mAh g-1 after 200 cycles at 0.2 A g-1 and a high capacity of 120.4 mAh g-1 at 10.0 A g-1), indicating that SrV4O9@rGO composite can be an ideal anode material for SIBs.

Reliability-Based Design Optimization of Additive Manufacturing for Lithium Battery Silicon Anode

Abstract With the blooming of the electric vehicle market and the advancement in the lithium-ion battery industry, silicon anode has shown great potential for the next-generation battery. Using the state-of-the-art additive manufacturing technique (three-dimensional (3D) holographic lithography), researchers have demonstrated that silicon anode can be fabricated as a three-dimensional bicontinuous porous microstructure. However, the volume fluctuation of the silicon anode caused by lithiation during the discharging process causes continuous capacity decay and poor cycling life. Besides, uncertainties are inherent in the manufacturing and usage processes, making it crucial to systematically consider them in the silicon anode design to improve its performance and reliability. To fill the gap between current silicon anode research and future industrial need, this study established a digital twin to investigate the optimal design for silicon anode under the uncertainties of additive manufacturing and battery usage. This study started with developing multiphysics finite element models of the silicon anode lithiation process to investigate the volume fluctuation of silicon. Then, surrogate models were built based on the results from the finite element models to reduce computational cost. The reliability-based design optimization (RBDO) was employed to find the best design point for the silicon anode, in which an outer optimization loop maximized the objective function and an inner loop dedicated to reliability analysis. Finally, the Pareto optimal front of the silicon anode designs was obtained and validated, which shows over 10% improvements in the silicon anode's total capacity and rate capability.

CO2 electrolysis to multi-carbon products in strong acid at ampere-current levels on La-Cu spheres with channels

Achieving satisfactory multi-carbon (C2+) products selectivity and current density under acidic condition is a key issue for practical application of electrochemical CO2 reduction reaction (CO2RR), but is challenging. Herein, we demonstrate that combining microenvironment modulation by porous channel structure and intrinsic catalytic activity enhancement via doping effect could promote efficient CO2RR toward C2+ products in acidic electrolyte (pH ≤ 1). The La-doped Cu hollow sphere with channels exhibits a C2+ products Faradaic efficiency (FE) of 86.2% with a partial current density of −775.8 mA cm−2. CO2 single-pass conversion efficiency for C2+ products can reach 52.8% at −900 mA cm−2. Moreover, the catalyst still maintains a high C2+ FE of 81.3% at −1 A cm−2. The channel structure plays a crucial role in accumulating K+ and OH- species near the catalyst surface and within the channels, which effectively suppresses the undesired hydrogen evolution and promotes C–C coupling. Additionally, the La doping enhances the generation of *CO intermediate, and also facilitates C2+ products formation.

Cu-In Dual Sites with Sulfur Defects toward Superior Ethanol Electrosynthesis from CO2 Electrolysis.

The electrosynthesis of multi-carbon chemicals from excess carbon dioxide (CO2) is an area of great interest for research and commercial applications. However, improving both the yield of CO2-to-ethanol conversion and the stability of the catalyst at the same time is proving to be a challenging issue. Here it is proposed to stabilize active Cu(I) and In dual sites with sulfur defects through an electro-driven intercalation strategy, which leads to the delocalization of electron density that enhances orbital hybridizations between the Cu-C and In-H bonds. Hence, the energy barrier for the rate-limiting *CHO formation step is reduced toward the key *OCHCHO* formation during ethanol production, which is also facilitated by the combined Cu site enabling C-C coupling and In site with a higher oxygen affinity based on both thermodynamic and kinetic calculations. Accordingly, such dual-site catalyst achieves a high partial current density toward ethanol of 409 ± 15mAcm⁻2 for over 120 h. Furthermore, a scaled-up flow cell is assembled with an industrial-relevant current of 5.7 A for over 36 h, in which the carbon loss is less than 2.5% and single-pass carbon efficiency is ≈19%.

Bilayer Porous Electrocatalysts for Stable and Selective Electrochemical Reduction of CO2 to Formate in the Presence of Flue Gas Containing NO and SO2.

The development of stable and selective electrocatalysts for converting CO2 to value-added chemicals or fuels has gained much interest in terms of their potential to mitigate anthropogenic carbon emissions. Most of the electrocatalysts are tested under pure CO2; however, industrial outlet flue gas contains numerous impurities, such as NO and SO2, which poison the electrocatalysts and alter the product selectivity. Developing electrocatalysts that are resistant to such impurities is essential for commercial implementation. Herein, we prepared bilayer porous electrocatalysts, namely, Sn, Bi, and In, on porous Cu foam mesh (Sn/Cu-f, Bi/Cu-f, and In/Cu-f) by a two-step electrodeposition process and employed these electrodes for the electrochemical reduction of CO2 to formate. It was observed that the bilayer porous electrocatalysts exhibited high CO2 reduction activity compared to catalysts coated on a Cu mesh. Among bilayer porous electrocatalysts, Sn/Cu-f and Bi/Cu-f electrocatalysts showed more than 80% faradaic efficiency (FE) toward formate production, with a formate partial current density of around -16 and -10.4 mA cm-2, respectively, at -1.02 V vs RHE. In/Cu-f electrocatalyst showed nearly 40% formate FE with formate partial current density of -15 mA cm-2 at -1.22 V vs RHE. We investigated the effect of NO and SO2 impurities (500 ppm of NO, 800 ppm of SO2, and 500 ppm of NO + 800 ppm of SO2) on these electrocatalysts' selectivity and stability toward formate. It was observed that the Bi/Cu-f electrocatalyst showed 50 h stability with 80 ± 5% formate FE, and Sn/Cu-f showed 18 h stability with above 80 ± 5% efficiency in the presence of NO and SO2 mixed with CO2. Furthermore, we studied the effect of CO2 concentration with Sn/Cu-f and Bi/Cu-f catalysts in the range of 15-100% CO2, for which formate FEs of 45-80% were observed.

Micro/Nano‐Structured Superhydrophobic Gas Diffusion Electrode for Boosting the Stability of Industrial‐Compatible Electrochemical CO Production in Flow Cells

AbstractElectrochemical flow cells based on gas diffusion electrodes (GDEs) provide a potential means to achieve industrial‐compatible massive CO production. However, the application of flow cells is hindered by the stability issue caused by GDE hydrophilizing and electrolyte flooding. The current strategies have certain limitations in maintaining the long‐term hydrophobicity of GDE. Inspired by the superhydrophobic materials in nature, here a constructionally engineered superhydrophobic GDE is presented for boosting the stability of CO2 reduction to CO in flow cells under industrial‐compatible current densities. This superhydrophobic GDE is comprised of micro/nano‐structured CNTs/graphene composites with abundant and robust single‐atomic Ni‐Nx active sites (NiSA‐CNT@G). The unique integrated hierarchical structure with highly exposed surface area and enhanced mass/charge transfer contributes to an industrial‐scale CO partial current density of 406.5 mA cm−2 with a FECO of 96.3% in a flow cell. Notably, the robust superhydrophobic micro/nanostructure efficiently resists electrolyte flooding over the GDE during the CO2RR, thus maintaining a stable three‐phase interface. Over 70 h stability is demonstrated at an industrial‐compatible current density of 300 mA cm−2. These results open up new opportunities for industrial‐level CO production via electrochemical CO2RR.

A Flow-Through Biosensor System Based on Pillar[3]Arene[2]Quinone and Ferrocene for Determination of Hydrogen Peroxide and Uric Acid

Simple and reliable electrochemical sensors are highly demanded in medicine and pharmacy for the fast determination of metabolites and biomarkers of diseases. In this work, a flow-through biosensor system was developed on the base of a screen-printed carbon electrode modified with pillar[3]arene[2]quinone and ferrocene implemented in carbon black. The modification was performed in a single step and resulted in the formation of a stable layer with good operation characteristics. Uricase was immobilized on the inner walls of a replaceable reactor by carbodiimide binding. A flow-through cell was manufactured by 3D printing from poly(lactic acid). The flow-through system was first optimized on the hydrogen peroxide assay and then used for the determination of 1 nM–0.1 mM uric acid (limit of detection 0.3 nM, 20 measurements per hour). Implementation of ferrocene resulted in a synergetic increase in the cathodic current of H2O2 reduction measured by flow switching in chronoamperometric mode. The developed system was tested on the determination of uric acid in artificial urine and Ringer–Locke solution and showed a recovery rate of 96–112%. In addition, the possibility of determination of H2O2 in commercial disinfectants was shown. Easy assembly, fast and reliable signal and low consumption of the reagents make the system developed attractive for routine clinical analysis of metabolites.

Copper oxide foam with high specific surface area for electrocatalytic reduction of CO2 to C2+ products

AbstractThe carbon dioxide reduction reaction (CO2RR) for the synthesis of high‐energy‐density and high‐value multi‐carbon (C2+) products has demonstrated considerable potential for practical applications. In this work, we design a novel copper oxide foam (OD‐Cu foam) catalyst through a high‐temperature calcination process, characterized by a substantial specific surface area. The distinctive three‐dimensional structure of the OD‐Cu foam catalyst and the metal oxide particles covered on its surface provide abundant active sites. The total Faradaic efficiency of 57.3% for C2+ products over the OD‐Cu foam is achieved at −0.85 V versus reversible hydrogen electrode (RHE). Furthermore, the partial current density for C2+ products over the OD‐Cu foam reaches 44.1 mA cm−2 at −0.95 V versus RHE, surpassing significantly that both of Cu foam (3.4 mA cm−2) and copper oxide foil (OD‐Cu foil) (1.6 mA cm−2). In addition, the integrated structure of the OD‐Cu foam, which does not require complex preparation processes, facilitates its application in CO2RR. These results underscore the significance of three‐dimensional structure and high specific surface area, emphasizing the considerable potential of this catalyst for effective and sustainable CO2 conversion.

CO electrolysis to multicarbon products over grain boundary-rich Cu nanoparticles in membrane electrode assembly electrolyzers

Producing valuable chemicals like ethylene via catalytic carbon monoxide conversion is an important nonpetroleum route. Here we demonstrate an electrochemical route for highly efficient synthesis of multicarbon (C2+) chemicals from CO. We achieve a C2+ partial current density as high as 4.35 ± 0.07 A cm−2 at a low cell voltage of 2.78 ± 0.01 V over a grain boundary-rich Cu nanoparticle catalyst in an alkaline membrane electrode assembly (MEA) electrolyzer, with a C2+ Faradaic efficiency of 87 ± 1% and a CO conversion of 85 ± 3%. Operando Raman spectroscopy and density functional theory calculations reveal that the grain boundaries of Cu nanoparticles facilitate CO adsorption and C − C coupling, thus rationalizing a qualitative trend between C2+ production and grain boundary density. A scale-up demonstration using an electrolyzer stack with five 100 cm2 MEAs achieves high C2+ and ethylene formation rates of 118.9 mmol min−1 and 1.2 L min−1, respectively, at a total current of 400 A (4 A cm−2) with a C2+ Faradaic efficiency of 64%.

Nitrogen-Doped Carbon Nanothin Film as a Buffer Layer between Anodic Graphite and Solid Electrolyte Interphase for Lithium-Ion Batteries.

Lithium-ion batteries are essential batteries for electric vehicle drive systems. Such batteries must provide stable performance over a long period of time. Therefore, the degradation or aging of the battery capacity must be improved. In the case of the current graphite anodes, graphite coated with an amorphous layer is used. It is known that the amorphous layer can reduce the irreversible capacity loss caused by the solid electrolyte interphase (SEI) layer. The amorphous carbon layers reduce the initial capacity due to higher electrical resistance. In this study, we aim to develop a buffer layer using nitrogen-containing graphene that would prevent the increase in electrical resistance while maintaining the amorphous structure. Coatings with different film thicknesses were prepared by using the solution plasma method. The thinnest sample was oven sintered to optimize the structure, especially the surface and interface of the layer. The battery capacity from charge-discharge experiments and the resistance change of each part from electrochemical impedance measurements were evaluated. The results showed that the coating layer increased the electrical resistance of the graphite anode. On the other hand, the resistance of the SEI layer was reduced by the coating layer. It can be predicted that the addition of the coating layer will increase the total charge transfer resistance (R ct) of the cell but will also improve the period average capacity in the long run. To be used as a practical material, the film thickness would need to be further reduced, and the balance between the loss of charge transfer resistance and the gain of SEI layer resistance would need to be further optimized.

Steering the Reaction Pathway of CO2 Electroreduction by Tuning the Coordination Number of Copper Catalysts.

Cu-based catalysts are optimal for the electroreduction of CO2 to generate hydrocarbon products. However, controlling product distribution remains a challenging topic. The theoretical investigations have revealed that the coordination number (CN) of Cu considerably influences the adsorption energy of *CO intermediates, thereby affecting the reaction pathway. Cu catalysts with different CNs were fabricated by reducing CuO precursors via cyclic voltammetry (Cyc-Cu), potentiostatic electrolysis (Pot-Cu), and pulsed electrolysis (Pul-Cu), respectively. High-CN Cu catalysts predominantly generate C2+ products, while low-CN Cu favors CH4 production. For instance, over the high-CN Pot-Cu, C2+ is the main product, with the Faradaic efficiency (FE) reaching 82.5% and a partial current density (j) of 514.3 mA cm-2. Conversely, the low-CN Pul(3)-Cu favors the production of CH4, achieving the highest FECH4 value of 56.7% with a jCH4 value of 234.4 mA cm-2. In situ X-ray absorption spectroscopy and Raman spectroscopy studies further confirm the different *CO adsorptions over Cu catalysts with different CN, thereby directing the reaction pathway of the CO2RR.

In Situ Generated CO Enables High-Current CO2 Reduction to Methanol in a Molecular Catalyst Layer.

Molecular catalysts such as cobalt phthalocyanine (CoPc) exhibit remarkable electrochemical activity in methanol production from CO2 or CO, but fast conversion with a high current density is still yet to be realized. While adopting flow cells with gas diffusion electrodes is a common approach to enhanced reaction rates, the current scientific and engineering knowledge primarily centers on metal particle-based catalysts like Cu. This focus overlooks the emerging heterogenized molecular catalysts with distinct physical and chemical properties. In this work, we observe that the partial current density of CO reduction to methanol catalyzed by tetraamine-substituted CoPc (CoPc-NH2) supported on carbon nanotubes (CNTs) remains below 30 mA cm-2, even with systematic optimization of structural and operational parameters of the flow cell. A comparative analysis with a Cu metal catalyst reveals that the porous and electrolyte-philic nature of CoPc-NH2/CNT leaves a large fraction of active sites deprived of CO under reaction conditions. To address this microenvironmental challenge, we directly use CO2 as the reactant, leveraging its faster diffusion rate in water compared to CO. Effective CO2 reduction generates CO in situ to feed the catalytic sites, achieving an unprecedently high partial current density for methanol of 129 mA cm-2. This research underscores the necessity for new insights and approaches in the development of molecular catalyst-based electrodes.

Impact of Surface Composition Changes on the CO2-Reduction Performance of Au-Cu Aerogels.

Over the past decades, the electrochemical CO2-reduction reaction (CO2RR) has emerged as a promising option for facilitating intermittent energy storage while generating industrial raw materials of economic relevance such as CO. Recent studies have reported that Au-Cu bimetallic nanocatalysts feature a superior CO2-to-CO conversion as compared with the monometallic components, thus improving the noble metal utilization. Under this premise and with the added advantage of a suppressed H2-evolution reaction due to absence of a carbon support, herein, we employ bimetallic Au3Cu and AuCu aerogels (with a web thickness ≈7 nm) as CO2-reduction electrocatalysts in 0.5 M KHCO3 and compare their performance with that of a monometallic Au aerogel. We supplement this by investigating how the CO2RR-performance of these materials is affected by their surface composition, which we modified by systematically dissolving a part of their Cu-content using cyclic voltammetry (CV). To this end, the effect of this CV-driven composition change on the electrochemical surface area is quantified via Pb underpotential deposition, and the local structural and compositional changes are visually assessed by employing identical-location transmission electron microscopy and energy-dispersive X-ray analyses. When compared to the pristine aerogels, the CV-treated samples displayed superior CO Faradaic efficiencies (≈68 vs ≈92% for Au3Cu and ≈34 vs ≈87% for AuCu) and CO partial currents, with the AuCu aerogel outperforming the Au3Cu and Au counterparts in terms of Au-mass normalized CO currents among the CV-treated samples.

Modulating anodic performance of halophilic electroactive microbial consortia with selective enrichment using metal-based terminal electron acceptors

Long start-up times and lack of robust halophilic electroactive microbes (EAM) challenge the implementation of microbial fuel cells (MFC) for treating saline wastewater. Here a pragmatic strategy is presented to selectively enrich halophilic EAM consortium capitalising on their cellular respiration process using graphene oxide (GO) and metal ions (Fe3+, Mn4+ and Cu2+) as the primary and secondary terminal electron acceptors (TEA), respectively. Enrichment of GO-respiring EAM consortium with Fe3+ ions enabled growth of an efficient anodic biofilm within a short start-up time of 50 h and generated up to 1.1 W/m3 while treating highly saline electrolyte (2 % NaCl). In conjunction with predictive genetic profiling, in-depth electrochemical analysis of the biofilm unravelled key mechanisms of direct extracellular electron transfer for generating high anodic currents. Additionally, the inclusion of Fe3+ ions as secondary TEA upregulated the metabolic activity of GO-respiring EAM, which subsequently influenced their anodic performance rather than the relative abundance of exoelectrogens in the biofilm. Thus, this study stimulates the discovery of novel EAM communities using an advanced and sensible design of selective media by varying the electron donor and TEA couplings.

Understanding the effect of cathodic reaction on corrosion-enhanced erosion in sand-entraining electrolyte

In this study, the pure erosion behaviour of pure iron and its erosion-corrosion behaviour under different anodic polarization currents were investigated in various cathodic reactions (oxygen reduction, hydrogen ion reduction, and water reduction) using a cylindrical stirring system. The corrosion-enhanced erosion (C-E) rates were determined for each condition. The results revealed that pure iron displayed similar pure erosion behaviour across all three cathodic reactions. When the cathodic reactions involve hydrogen ion reduction or water reduction, the erosion-corrosion of pure iron manifested as uniform damage, with the reduction in hardness being the main cause of the C-E in this case. Conversely, in the case of oxygen reduction reaction as the cathodic reaction, the erosion-corrosion presented as pitting damage, with the reduction in hardness resulting from localized concentration of anodic current and the formation of easily worn protruding flaky iron structures at the edges of the pits as the main mechanism of the C-E. Moreover, linear and exponential relationships were found between the C-E rate and the anodic current density for uniform damage and pitting damage, respectively. Finally, the concept of surface equivalent hardness was proposed, along with the establishment of a mathematical model for surface equivalent hardness based on the relationships between the C-E rate and the anodic current density. Utilizing the surface equivalent hardness enables the evaluation of the erosion rate on material surfaces considering the coupled effect.