Electrode Surface Area Research Articles

Plant-based zinc nanoflowers assisted molecularly imprinted polymer for the design of an electrochemical sensor for selective determination of abrocitinib

The first electrochemical sensor application in the literature is described for the sensitive and selective determination of the selective Janus kinase (JAK)-1 inhibitor abrocitinib (ABR). ABR is approved by the U.S. Food and Drug Administration (FDA) for the treatment of atopic dermatitis. The molecularly imprinted polymer (MIP)-based sensor was designed to incorporate zinc nanoflower (ZnNFs)-graphene oxide (GO) conjugate (ZnNFs@GO), synthesized from the root methanolic extract (RME) of the species Alkanna cappadocica Boiss. et Bal. to improve the porosity and effective surface area of the glassy carbon electrode (GCE). Furthermore, the MIP structure was prepared using ABR as a template molecule, 4-aminobenzoic acid (4-ABA) as a functional monomer, and other additional components. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the surface and structure of the synthesized nanomaterial and MIP-based surface. Among the electrochemical methods, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were preferred for detailed electrochemical characterization, and differential pulse voltammetry (DPV) was preferred for all other electrochemical measurements using 5.0 mM [Fe(CN)6]3–/4– solution as the redox probe. The MIP-based sensor, which was the result of a detailed optimization phase, gave a linear response in the 1.0 × 10–13 – 1.0 × 10–12 M range in standard solution and serum sample. The obtained limit of detection (LOD) and limit of quantification (LOQ) values and recovery studies demonstrated the sensitivity, accuracy, and applicability of the sensor. Selectivity, the most important feature of the MIP-based sensor, was verified by imprinting factor calculations using ibrutinib, ruxolitinib, tofacitinib, zonisamide, and acetazolamide.Graphical

Nucleation of Pitting and Evolution of Stripping on Lithium-Metal Anodes.

The stripping reaction of lithium (Li) will greatly impact the cyclability and safety of Li-metal batteries. However, Li pits' nucleation and growth, the origin of uneven stripping, are still poorly understood. In this study, we analyze the nucleation mechanism of Li pits and their morphology evolution with a large population and electrode area (>0.45 cm2). We elucidate the dependence of the pit size and density on the current density and overpotential, which are aligned with classical nucleation theory. With a confocal laser scanning microscope, we reveal the preferential stripping on certain crystal grains and a new stripping mode between pure pitting and stripping without pitting. Descriptors like circularity and the aspect ratio (R) of the pit radius to depth are used to quantify the evolution of Li pits in three dimensions. As the pits grow, growth predominates along the through-planedirection, surpassing the expanding rate in the in-plane direction. After analyzing more than 1000 pits at each condition, we validate that the overpotential is inversely related to the pit radius and exponentially related to the rate of nucleation. With this established nucleation-overpotential relationship, we can better understand and predict the evolution of the surface area and roughness of Li electrodes under different stripping conditions. The knowledge and methodology developed in this work will significantly benefit Li-metal batteries' charging/discharging profile design and the assessment of large-scale Li-metal foils.

In situ patterning of nickel/sulfur-codoped laser-induced graphene electrode for selective electrocatalytic valorization of glycerol

The electrocatalytic valorization of glycerol is an emerging upcycling process for the biomass utilization. In this work, nickel/sulfur-codoped laser-induced graphene (LINiSG) on flexible polyimide film was fabricated and demonstrated as a self-supported and binder-free monolithic electrode for electrocatalytic glycerol oxidation reaction (EGOR) towards the selective generation of value-added three-carbon (C3) chemicals. The laser-induced in-situ and synchronous carbonization of polysulfone and Ni precursor was demonstrated to remarkably promote both the electrochemical surface area and Ni loading of LINiSG electrode. These synergistic merits are considered as the main origin for its enhanced EGOR activity and stability, showing much smaller Tafel slope and 2-fold enhanced current density, as compared to LINiG electrode without the co-carbonization of polysulfone. The influence of experimental parameters has been systematically investigated by the product analysis, achieving an average 94.7 % C3 selectivity and 76.1 % C3 Faradaic efficiency with a high selectivity of dihydroxyacetone (ca. 67.7 %) in near-neutral conditions, which is better than most of the reported EGOR electrodes operated in near-neutral conditions. This work demonstrated the viability of using flexible self-supported and binder-free LIG electrode with rational design and preparation approach for electrocatalytic valorization of biomass.

An experimentally validated model for anodic H2O2 production in alkaline water electrolysis and its implications for scaled-up operation

The anodic co-production of hydrogen peroxide (H2O2) during alkaline water electrolysis has gained interest as a sustainable alternative for anthraquinone oxidation. However, electrochemical H2O2 production is often studied with idealized laboratory setups to determine the H2O2 formation kinetics. In this work, we perform the reaction with industrially relevant operating principles using a flow cell with separately recirculating anolyte and catholyte. We then fit the data to an analytical model that we derive based on mole balances that accounts for anodic generation, anodic oxidation, and bulk disproportionation of H2O2, as well as electrolyte volumes and electrode surface area. We performed experiments at 100, 200, and 300 mA cm-2 to derive values for the reaction system. At 200 mA cm-2, we found a generation rate of 0.037 mmol min-1 cm-2 (FEH2O2 = 59%) and an anodic decomposition rate constant of 0.304 cm min-1, with a bulk disproportionation rate constant of 1.85 × 10-3 min-1. We successfully applied our model to two sources in literature to derive values for their systems as well. In all cases, the contribution of anodic oxidation of H2O2 was found to be the larger loss mechanism in comparison to bulk disproportionation. Using the analytical model, we show that decreasing the reservoir volume is a simple way to increase the H2O2 concentration over time. Further refinement of the model can be achieved through the use of mass transfer relationships based on electrolyzer geometries to describe the anodic oxidation of H2O2 in the mole balance equations.

Evaluating Bacterial Nanocellulose Interfaces for Recording Surface Biopotentials from Plants.

The study of plant electrophysiology offers promising techniques to track plant health and stress in vivo for both agricultural and environmental monitoring applications. Use of superficial electrodes on the plant body to record surface potentials may provide new phenotyping insights. Bacterial nanocellulose (BNC) is a flexible, optically translucent, and water-vapor-permeable material with low manufacturing costs, making it an ideal substrate for non-invasive and non-destructive plant electrodes. This work presents BNC electrodes with screen-printed carbon (graphite) ink-based conductive traces and pads. It investigates the potential of these electrodes for plant surface electrophysiology measurements in comparison to commercially available standard wet gel and needle electrodes. The electrochemically active surface area and impedance of the BNC electrodes varied based on the annealing temperature and time over the ranges of 50 °C to 90 °C and 5 to 60 min, respectively. The water vapor transfer rate and optical transmittance of the BNC substrate were measured to estimate the level of occlusion caused by these surface electrodes on the plant tissue. The total reduction in chlorophyll content under the electrodes was measured after the electrodes were placed on maize leaves for up to 300 h, showing that the BNC caused only a 16% reduction. Maize leaf transpiration was reduced by only 20% under the BNC electrodes after 72 h compared to a 60% reduction under wet gel electrodes in 48 h. On three different model plants, BNC-carbon ink surface electrodes and standard invasive needle electrodes were shown to have a comparable signal quality, with a correlation coefficient of >0.9, when measuring surface biopotentials induced by acute environmental stressors. These are strong indications of the superior performance of the BNC substrate with screen-printed graphite ink as an electrode material for plant surface biopotential recordings.

Degradation of Styrene-Poly(ethylene oxide)-Based Block Copolymer Electrolytes at the Na and K Negative Electrode Studied by Microcalorimetry and Impedance Spectroscopy

The electrode-electrolyte interface of alkali metal electrodes and solid polymer electrolytes (SPE) is challenging to access because solid electrolytes are difficult to remove without damaging the interphase region. Herein, the two non-invasive techniques isothermal microcalorimetry (IMC) and electrochemical impedance spectroscopy (EIS) are combined to explored degradation processes of reactive sodium and potassium metal electrodes in contact with SPEs. Comparison of the parasitic heat flows and interfacial resistances at different current densities with a liquid electrolyte (LE) system showed marked differences in aging behaviour. The data also suggest that the electrochemically active surface area of alkali metal electrodes increase with cycling, leading to larger parasitic heat flows and indicating morphological changes. SPE-based cells exhibit similar levels of parasitic heat flow at different current densities, which is in stark contrast to the LE cell where a strong correlation between the two is evident. The ambiguity of EIS spectra is challenging due to the overlapping time constants of the underlying electrode processes. However, equivalent circuit modelling can be used to follow trends in resistance evolution, for example to track the rapidly increasing cell impedance in K/K symmetric cells during a 48 h equilibration interval prior to cycling, which abruptly disappeared once cycling begins.

A composite electrode of stabilized lithium metal powder and lithiophilic Ag-coated Cu powder for lithium metal batteries

In this study, we fabricate a composite electrode of lithium metal powder (LMP) and Ag-coated Cu powder (Li/Cu@Ag) for lithium metal battery simply by Ag-coating on Cu powder through galvanic replacement and pelletizing their mixture. Due to the structure of the composite electrode and high surface area of LMP, local current density can be reduced. The lithiophilic Ag particles on the Cu powder lower lithium nucleation overpotential and enable uniform lithium plating. The Li/Cu@Ag electrode shows superior electrochemical performance with this synergetic effect and the reason for the improvement has been investigated. Specifically, a long lifespan of 400 h at a current density of 1 mA/cm2 is achieved with a Li||Li symmetric cell when using the Li/Cu@Ag electrode in a corrosive carbonate electrolyte. In addition, LiFePO4||Li/Cu@Ag cell shows excellent cycling stability and high-capacity retention (over 74 % after 400 cycles at 3C).

Determination of the Diffusion Coefficient in Electrodeposition Reactions by Electrochemical Impedance Spectroscopy: A Case Study of Cobalt in Molten LiCl-KCl Salt

Compared to direct current (DC) techniques, electrochemical impedance spectroscopy (EIS) allows for a more accurate determination of the diffusion coefficient of metal ions in electrodeposition reactions. However, its actual application has been less attempted due to the difficulty in determining complex parameters, such as the concentration of deposited species in the electrode matrix. Here, we introduce a simplified approach to facilitate the EIS application to electrodeposition reactions, using the Co(II)/Co(0) reaction in molten LiCl-KCl salt as a case study. The working electrode surface area was determined by the photography of the electrochemical cell taken in situ. The diffusion coefficients of Co(II) in the LiCl-KCl salt, determined by EIS, were found to be (3.56 ± 0.49) × 10−5 cm2/s and (1.61 ± 0.12) × 10−5 cm2/s for the tungsten and liquid bismuth electrodes, respectively. The possible reasons for the observed discrepancy in the diffusion coefficients of Co(II) obtained from the two different electrodes were discussed.

Green and Efficient Removal of Toxic Lead and Chromiumfrom Synthetic Leather Tannery Wastewater using Electrocoagulation

Most of leather tanneries in Pakistan dispose of tannery effluent untreated in sewage lines causing serious harmful environmental impact. Some of tanneries use conventional activated sludge process releasing large quantity of sludge and not effective for treating heavy metal in leather tanneries. The manuscript deals with implementation of electrocoagulation technology for removal of Cr and Pb from Leather tannery effluent, investigation of operating parameters current density, treatment time and pH on removal efficiency. Electrodes was made of Iron having dimension 9.5 cm x 0.6 cm x 0.4 cm and affective surface area of electrode was 76 cm<sup>2</sup>. After conducting different experiments at various operating conditions, pH 3.5 and current density 18.8 milliamp/cm2 was found to be optimized condition for treating 1 liter of synthetic leather tannery effluent. The maximum removal efficiency of chromium and lead was obtained 87.8 % and 62.7 % respectively at pH 3.5 and current density of 18.8 milliamp/cm<sup>2</sup>. The EDX analysis of sludge shows presence of chromium, lead and iron element in sludge and FTIR analysis shows the presence of hydroxyl functional group in sludge, it is strong evidence of iron polymer complexes formation with chromium and lead during treatment of synthetic leather tannery wastewater. Both of these analysis show strong evidence of effective electrocoagulation process. It was proved that electrocoagulation can effectively treat synthetic leather tannery effluent. The SEM analysis shows production of coagulant on surface of electrode.

Tailoring Interfaces for Enhanced Methanol Production from Photoelectrochemical CO2 Reduction.

Efficient and stable photoelectrochemical reduction of CO2 into highly reduced liquid fuels remains a formidable challenge, which requires an innovative semiconductor/catalyst interface to tackle. In this study, we introduce a strategy involving the fabrication of a silicon micropillar array structure coated with a superhydrophobic fluorinated carbon layer for the photoelectrochemical conversion of CO2 into methanol. The pillars increase the electrode surface area, improve catalyst loading and adhesion without compromising light absorption, and help confine gaseous intermediates near the catalyst surface. The superhydrophobic coating passivates parasitic side reactions and further enhances local accumulation of reaction intermediates. Upon one-electron reduction of the molecular catalyst, the semiconductor-catalyst interface changes from adaptive to buried junctions, providing a sufficient thermodynamic driving force for CO2 reduction. These structures together create a unique microenvironment for effective reduction of CO2 to methanol, leading to a remarkable Faradaic efficiency reaching 20% together with a partial current density of 3.4 mA cm-2, surpassing the previous record based on planar silicon photoelectrodes by a notable factor of 17. This work demonstrates a new pathway for enhancing photoelectrocatalytic CO2 reduction through meticulous interface and microenvironment tailoring and sets a benchmark for both Faradaic efficiency and current density in solar liquid fuel production.

Evaluation of treatment and energy efficiencies of an advanced electrochemical system for Chlorella removal equipped with aluminum, graphite, and RGO nanoparticles-coated cathodes

Advanced material sciences and technologies can help to address environmental challenges in order to achieve sustainable development goals by developing innovative materials capable of mitigating energy consumption in treatment systems. In this study, an innovative electrocoagulation unit for algae removal was optimized, and the effects of various variables, including novel cathode materials (i.e., graphite and reduced graphene oxide nanoparticles), on treatment efficiency and energy consumption were evaluated. Reduced graphene oxide nanoparticles were synthesized and then immobilized on the graphite cathode surface with the modified Hummer's method. Stabilization of nanoparticles was achieved with polytetrafluoroethylene. The use of the reduced graphene oxide nanoparticles-coated cathode led to a significant decrease (42.93%) in energy consumption, compared to the case with an aluminum cathode. In the optimum conditions (a current density of 3 mA/cm2, an electrolyte concentration of 2 g/L, an electrode surface area of 56 cm2, a processing time of 60 min, and a sedimentation time of 30 min), the novel electrocoagulation unit, equipped with an aluminum anode and a reduced graphene oxide nanoparticles-coated cathode electrode, achieved removal efficiencies of 72.69% for Chlorella species and 72.96% for turbidity.

Electrochemical Sensing with Spatially Patterned Pt Octahedra Electrodes

AbstractLocally controlling the position of electrodes in 3D can open new avenues to collect electrochemical signals in complex sensing environments. Implementing such electrodes via an electrical network requires advanced fabrication approaches. This work uses corner lithography and Pt ALD to produce electrochemical 3D electrodes. The approach allows the fabrication of (sub)micrometer size Pt octahedra electrodes spatially supported over 3D fractal‐like structures. As a proof of concept, electrochemical sensing of ferrocyanide in biofouling environments, e.g., bovine serum albumin (BSA) and Pseudomonas aeruginosa (P. aeruginosa), is assessed. Differences between before and after BSA addition show a reduction in the active electrode surface area (ΔAeff) ≈49% ± 7% for the flat electrode. In comparison, a ΔAeff reduction of 25% ± 2% for the 3D electrode has been found. The results are accompanied by a 24% ± 16% decrease in peak current for the flat Pt substrate and a 14% ± 5% decrease in peak current for the 3D electrode 24 h after adding BSA. In the case of P. aeruginosa, the 3D electrode retains electrochemical signals, while the flat electrode does not. The results demonstrate that the 3D Pt electrodes are more stable than their flat counterparts under biofouling conditions.

Electrode Surface Area Impacts Measurement of High Frequency Oscillations in Human Intracranial EEG.

High-frequency oscillations (HFOs) are a promising prognostic biomarker of surgical outcome in patients with epilepsy. Their rates of occurrence and morphology have been studied extensively using recordings from electrodes of various geometries. While electrode size is a potential confounding factor in HFO studies, it has largely been disregarded due to a lack of consistent evidence. Therefore, we designed an experiment to directly test the impact of electrode size on HFO measurement. We first simulated HFO measurement using a lumped model of the electrode-tissue interaction. Then eight human subjects were each implanted with a high-density 8x8 grid of subdural electrodes. After implantation, the electrode sizes were altered using a technique recently developed by our group, enabling intracranial EEG recordings for three different electrode surface areas from a static brain location. HFOs were automatically detected in the data and their characteristics were calculated. The human subject measurements were consistent with the model. Specifically, HFO rate measured per area of tissue decreased significantly as electrode surface area increased. The smallest electrodes recorded more fast ripples than ripples. Amplitude of detected HFOs also decreased as electrode surface area increased, while duration and peak frequency were unaffected. These results suggest that HFO rates measured using electrodes of different surface areas cannot be compared directly. This has significant implications for HFOs as a tool for surgical planning, particularly for individual patients implanted with electrodes of multiple sizes and comparisons of HFO rate made across patients and studies.

Anode biomass rather than soluble organic matter is fuel for electricity production in microbial fuel cell at longer hydraulic retention time

This study presents a novel method for independently calculating organic matter (OM) removal and electricity generation in a microbial fuel cell (MFC) treating sewage. This methodology used OM concentration as the exclusive variable for input, facilitating the prediction of electricity generation with variable Coulombic efficiency. The employed MFC, of tubular design, incorporates an air core surrounded by a carbon-based cathode, an anion exchange membrane, nonwoven graphite fabric, and encircled by twelve carbon brush anodes. This setup successfully reduced chemical oxygen demand (COD) from 180 to 50 mg L−1 and biological oxygen demand (BOD) from 84 to 15 mg L−1 within a 35 h hydraulic retention time (HRT). The resulting effluent BOD satisfies Japanese wastewater treatment standards. In the early HRT phase, the MFC exhibited rapid OM reduction, followed by a stabilization of OM concentration. Despite varying HRTs and the sustained OM levels at prolonged HRTs, the MFC consistently generated 0.29 ± 0.14 A m−2. This apparent contradiction prompted the consideration of additional OM sources from the anode biomass (Cb). Calculating electricity production based on OM concentration rather than OM degradation was achieved by assessing anode resistance (RAn) across different levels of OM supplementation, employing the Butler–Volmer equation. This approach, incorporating considerations for Cb and RAn, accurately reproduced MFC performance. It was observed that OM supplementation from Cb constituted 50% at 11 h HRT and escalated to 90% at 27 h HRT. Further analysis, including 16S rRNA gene-based microbial community profiling, indicated that higher cathode resistance (RCat) at 1.0 Ω m2, compared to a minimum RAn of 0.10 Ω m2, favored methanogenesis over electrogenesis on the carbon brushes. This finding underscores the importance of reducing RCat and minimizing electrode distance, coupled with enhancing the specific surface area of both electrodes, as crucial factors for the advancement of MFC technology.

Development of Nanoporous Nickel Oxide Materials as Electrodes for Supercapacitors

As a potential electrochemical energy storage device, supercapacitor has been researched owing to its low weight, excellent power density, outstanding charging rate, and long durability. For the supercapacitor, the electrode material and its morphology determine its overall performance. Nickel oxide (NiO) is a promising material for the electrode because of its low cost, high specific capacitance, and eco-friendly manufacturing process. In this research, we developed a simple and cost-effective method to fabricate supercapacitor electrodes by electrospinning and thermal annealing, making porous nickel oxide nanofibers directly grow on 3D-nickel foam. The binder-free design and porous structure of electrodes enhance the ion transport and electron transfer in the supercapacitor. The crystal structure of NiO was identified by X-ray diffractometry (XRD). The morphological and microstructural characterization was analyzed by scanning electron microscopy (SEM). The electrochemical test was carried out in a three-electrode electrochemical cell with the obtained foamed NiO as the working electrode, the platinum sheet as the counter electrode, and the Ag/Cl electrode as the reference electrode. The electrochemical performance was evaluated by using cyclic voltammetry (CV), galvanostatic charge/discharge technique, and electrochemical impedance spectroscopy (EIS). Due to the large specific surface area and good electrical conductivity of the NiO electrode, the supercapacitor exhibited excellent electrochemical performance (591 F/g at 2 A/g). After 1500 cycles of charging and discharging at 10 A/g, the capacitance of the supercapacitor using the NiO electrode increased by 21.7% with excellent cycle stability.

Electrospun carbon nanofibers decorated with NiS2-FeS2 used as efficient counter electrode for quantum dot sensitized solar cells

NiS2-FeS2 composite material is uniformly coated on CNFs by a one-step hydrothermal method with carbon nanofibers (CNFs) prepared by the electrostatic spinning method. A composite NiS2-FeS2/CNFs with Ti-mesh substrate counter electrode (NiS2-FeS2/CNFs CE) is prepared by scraping and coating method on a metal titanium mesh and applied to quantum dot sensitized solar cells (QDSSCs). The photoelectric power conversion efficiency of QDSSCs assembled on NiS2-FeS2/CNFs electrode substrate is 9.85%, which is much higher than that of traditional Cu2S/brass (7.85%). The exceptional achievement can be attributed to the superb amalgamation of the Ti-mesh's excellent electrical conductivity and the NiS2-FeS2/CNFs nanostructure's high and stable catalytic activity. The co-loading of NiS2 and FeS2 reduces the particle size of the composite, enhancing the specific surface area of the counter electrode. It provides abundant catalytic active sites for QDSSCs. The experimental results show that NiS2-FeS2 is expected to be a competitive and efficient QDSSCs CE material.

Designing advanced 0D/2D heterojunctions of N, S-co-doped carbon dots/Ti3C2Tx MXene nanosheets in electrochemical sensor applications

Ti3C2Tx MXene has demonstrated well-established sensitivity in electrochemical sensing but is susceptible to oxidation. Nitrogen-sulfur doped carbon dots (N, S-CDs) were functionalized on Ti3C2Tx MXene nanosheets via a surface modification strategy, leading to significant enhancement in the performance of Ti3C2Tx MXene. The incorporation of N, S-CDs into Ti3C2Tx MXene nanosheets effectively prevents the aggregation of Ti3C2Tx MXene flakes, resulting in improvement of the interlayer spacing to 1.578 nm and a threefold expansion of the specific surface area. Furthermore, the N, S-CDs contribute to increase the effective active surface area of the Ti3C2Tx MXene electrode, facilitating accelerated the electron transfer rates and providing additional active sites. On this basis, a galvanic sensor for dopamine (DA) detection was attained through loading N, S-CDs/Ti3C2Tx on glassy carbon electrodes. The optimized sensor achieved a linear detection range of 1 μM–1000 μM for DA, with a detection limit of 0.91 μM (S/N = 3). This work presents a promising approach for the utilization of chemically stable Ti3C2Tx MXene and MXene-based sensors, offering a new avenue for quantitative detection of DA that holds potential for application in real sample analysis.

Fabrication of efficient and economical dye-sensitized solar cells using carbon-coated nanotextured silicon wafers counter electrodes

Significant progress has been made in various fields of photovoltaics in response to the growing demand for alternative energy resources. Silicon technologies dominate the current solar cell market, but carbon-based photovoltaics are known for their ability to be produced at low cost and in large quantities. The electrocatalyst accelerates the conversion of tri-iodide into iodide ions at the interface between the counter electrode and the electrolyte, according to DSSC principle. During the catalytic process, the accessible sites for the reaction between the reactants and the catalyst are greatly influenced by the surface area and morphology of the counter electrode and electrocatalyst. Therefore, in this work, silicon micro cubes with different patterns were fabricated using lithography, and a carbon layer has been coated directly using chemical vapor deposition on the surface of silicon samples with 15, 30, and 60 mins growth times. The functionalized silicon surface with the carbon layer subsequently demonstrated electrocatalytic activities for iodide/triiodide reduction. In DSSCs, the carbon-coated samples have been utilized as counter electrodes. The samples were characterized using Raman spectroscopy and scanning electron microscopy. DSSCs were fabricated for each synthesized counter electrode, and DSSCs performance has been analyzed for each DSSC. Utilizing carbon-coated nanotextured silicon wafers as the counter electrodes, DSSCs were able to achieve the maximum power conversion efficiency of 6.73%. The current results pave the way toward the replacement of expensive Pt-based conventional DSSCs.

Advanced Analytical System with Standardized Data Analysis for Electrochemical CO2 Reduction

Electrochemical CO2 reduction (CO2RR) is a promising way to convert CO2 emissions into sustainable fuels and chemicals, approaching a circular carbon economy. 1 Depending on catalyst type and reaction conditions, different gaseous and liquid products can be obtained from the CO2RR, and their production rates vary with reaction time. Thus, assessing the product distribution online during CO2RR is a key component of any catalytic performance analysis. 2,3 However, while gaseous products are readily analyzed online, liquid products are assessed typically only at the end of the reaction due to the lack of suitable automated liquid sampling and analysis methods. In addition, electrolyzer parameters such as gas flow rates, temperatures and pressures are seldom recorded, causing the loss of significant information on catalysts, electrodes, and electrolyzers behavior.To overcome these issues, we assemble a comprehensive analytical system coupling online gas and liquid product analysis by chromatography (leveraging a special automated liquid sampling valve) with electrochemical protocols to assess CO2RR performance, electrolyzer cell resistance and electrode surface area. In addition, we record CO2 gas flow rates, electrolyzer temperatures, and gas and liquid pressures. 4 To rapidly and reproducibly handle the large and heterogeneous data volume obtained we implement a standardized data pipeline based on our own open-source software,5 which automatically parses the numerous different raw data files, composes a data set following FAIR practices,6 and post-processes and plots the data in a standardized way (see example in Fig. 1 below). We validate the analytical system by carrying out CO2RR at 200 mA/cm2 on Cu gas diffusion electrodes, following the changes in selectivity with reaction time for > 10 gaseous and liquid products, and recording mass flow rates, electrolyzer temperatures and pressures. The modular nature of our analytical system, combined with the standardized data pipeline, allows us to freely increase the number and type of sensors used with minimal impact on the data analysis time, as well as to multiplex our analysis to parallel electrolyzer cells, paving the way for a much deeper and faster understanding of the function of CO2RR catalysts, electrodes, and electrolyzers.

Laser Perforated Dual-Scale Porous Electrodes Considering the Interdigitated Flow Field for Vanadium Redox Flow Battery

The conflict between the specific surface area and hydraulic permeability of carbon-based porous electrodes limits the further improvement of redox flow battery (RFB) system performance. Dual-scale electrode design is a feasible approach to overcome this contradiction. In this study, we prepared dual-scale electrodes by perforating graphite felts using an infrared laser. Based on the symmetry of the interdigitated flow field structure, we proposed three dual-scale structure designs with different combinations of large and small pores and tested their performance on a vanadium redox flow battery (VRFB) single cell. The results showed that the design with perforations under the center of the rib could increase the maximum power density by approximately 2.4 times compared to the original electrode. Furthermore, to investigate the effect of the large pores formed by laser perforation on the local electrolyte velocity, active species concentration, and reaction rate distribution, we proposed a pore-network model and investigated the influence of different combinations of large and small pores and different operating conditions on overall performance through numerical simulation. The results showed that the optimal combination of large and small pores is related to the flow rate and other operating conditions, and that setting large pores under the rib near the outlet channel is expected to provide more performance gains in VRFBs equipped with interdigitated flow fields under typical operating flow rates.