Carbon Electrode Materials Research Articles

Nitrogen and sulfur co-doped carbonized lignin nanotubes for supercapacitor applications

Carbon electrode material is crucial for the development of electric double-layered supercapacitor in clean energy storage and rechargeable aspects. Although lignin consists the promising biomass based carbon resource for containing higher carbon atom ratio than 60 %, it is still the difficult challenge to precisely tailoring the porous structure characteristics and surface property to facilitate the electrolyte penetration and rapid ion transportation. Herein, the lignin nanotubes (LNT) were successfully synthesized in a convenient molecular self-assembly way, which were subsequently carbonized and activated, with introduction of melamine as nitrogen doping agent, into hetero-atom doped lignin carbon nanotubes (LCNT) as electrode material for supercapacitor. The resultant LCNT exhibit excellent pore structure, and high degree of graphitization. At a current density of 0.5 A/g, the as high specific capacitance as 391.4 F/g was achieved. Furthermore, under symmetric double-layered capacitor electrode systems, the as prepared N, S co-doped LCNT electrode demonstrated a specific capacitance of 28.6 F/g at a high current density of 20 A/g, which presented a practically applicable energy storage efficiency. It has convincingly demonstrate the substantial potential of LCNT as biomass derived carbon materials for electrochemical energy storage devices, positioning them as a promising and competitive candidate for electrode materials.

Capacitive deionization: Capacitor and battery materials, applications and future prospects

Water scarcity all over the world attracts alternative methods to purify saline water and supplement the available dwindling freshwater resources. Capacitive deionization (CDI) is hopeful to supply water to the population due to operation at low potential along with low energy expenditure when low salinity (5 mM NaCl) feed water solutions are desalinated. Electrode material is the main controlling factor in CDI system and a lot of efforts are devoted to develop excellent materials for better CDI performance. So far, carbon materials are widely used as the electrode for CDI, though limitations such as co-ion expulsion and faradaic reactions hinder their full utilization. Alternatively, battery materials are used since their performance is great due to mitigation of co-ions ejection as well as faradaic reactions. In 2019 our group reviewed factors affecting the performance of activated carbon electrode materials and revealed lack of selectivity, co-ion expulsion, low electrical conductivity and inappropriate pore size distribution to largely contribute to its low salt removal capacity [1]. Therefore, herein, we extend the discussion beyond AC to include other carbons such as aerogels, nanotubes, graphenes etc., and battery materials such as MXenes, sodium super ionic conductors, and BiOCl to mention the few. This article also discusses the extent CDI is applied in the laboratory scale as well as in the field for desalination of real water, wastewater remediation and removal of harmful contaminants to substantiate what it can offer beyond the laboratory experiments. The work is expected to save as a complete reference for the progress of CDI electrode materials and its applications in water purification.

Hydrophilic porous activated biochar with high specific surface area for efficient capacitive deionization

Porous carbon electrode materials were prepared by carbonization and alkali activation from three natural porous biomasses, lotus petiole (LP), sunflower plate (SP), and lotus seedpod (LS). The pore structure, surface characteristics, and electrochemical properties of the three activated biochars were investigated and related to their CDI performance. The results indicated that the three activated biochars were hydrophilic and negatively charged, with a high specific surface area and an abundance of micropores. Due to the best surface wettability, highest specific capacitance, and shortest charge-discharge time, lotus petiole-based activated biochar (LPCK) had the highest electrosorption capacity of 8.67 mg·g−1 and faster desalination rate of 0.24 mg·g−1·min−1. Cyclic voltammetry and adsorption kinetics results indicate that the double-layer electrostatic adsorption mechanism dominated the CDI processes of the three activated biochars. The use of three biomass wastes provides low-cost, eco-friendly, and sustainable materials for the development of CDI electrodes.

High energy-efficiency decomplexation of metal-complexes by H*-mediated electro-reduction on hydroxyphenyl Co-porphyrin catalysts

Electrochemical reduction of metal-organic complex pollutants has been recognized as an environmental benign method that operates at mild condition. However, the selective reduction of metal complexes and energy consumption in cathodic process are still a big challenge. Herein, we found that hydroxyphenyl Co-porphyrin catalyst (CoTH@NG) realizes the highly selective decomplexation of metal-organic complexes by H* -mediated reduction, and simultaneously the impressive recovery efficiency of metal ions. Density functional theory (DFT) confirms the generation and capturing ability of H* on CoTH@NG, verifying the dominant role of H* -mediated reduction in the selective decomplexation of Cu-EDTA. CoTH@NG realizes the superior energy efficiency for Cu-EDTA removal (279.3 g kWh−1 of EEOCu-EDTA) and Cu recovery (48.6 g kWh−1 of EEOCu), which are remarkably 3.3 × 102 and 9.7 × 102 times higher than traditional carbon cloth electrode. Moreover, the recovered Cu0(s) nanowires on the electrode surface can be efficiently regenerated in HCOOH by a galvanic reaction through the electron channel of CoTH@NG, regenerating catalytic electrode. This is one of the pioneer studies on H* -mediated electro-reduction decomplexation of metal-complexes, metal recovery, and electrode regeneration on CoTH@NG, which providing a technical strategy for developing efficient electrocatalytic system for pollution control.Environmental ImplicationMetal complexes is a dramatic increase in the electroplating and mining industries, and seriously affect both public health and environmental sustainability. Our work reported a new hydroxyphenyl Co-porphyrin catalyst (CoTH@NG) which achieves the selective decomplexation of metal-organic complexes, and simultaneously the recovery of metal ions. CoTH@NG realizes the superior energy efficiency for Cu-EDTA removal (279.3 g kWh−1) and Cu0(s) recovery (48.6 g kWh−1), which are remarkably 3.3 × 102 and 9.7 × 102 times higher than traditional carbon cloth electrode. Moreover, the recovered Cu0(s) can be efficiently regenerated in HCOOH by a galvanic reaction through the electron channel of CoTH@NG, regenerating catalytic electrode.

Covalent versus noncovalent attachments of [FeFe]‑hydrogenase models onto carbon nanotubes for aqueous hydrogen evolution reaction

In an effort to develop the biomimetic chemistry of [FeFe]‑hydrogenases for catalytic hydrogen evolution reaction (HER) in aqueous environment, we herein report the integrations of diiron dithiolate complexes into carbon nanotubes (CNTs) through three different strategies and compare the electrochemical HER performances of the as-resulted 2Fe2S/CNT hybrids in neutral aqueous medium. That is, three new diiron dithiolate complexes [{(μ-SCH2)2N(C6H4CH2C(O)R)}Fe2(CO)6] (R = N-oxylphthalimide (1), NHCH2pyrene (2), and NHCH2Ph (3)) were prepared and could be further grafted covalently to CNTs via an amide bond (this 2Fe2S/CNT hybrid is labeled as H1) as well as immobilized noncovalently to CNTs via π-π stacking interaction (H2) or via simple physisorption (H3). Meanwhile, the molecular structures of 1–3 are determined by elemental analysis and spectroscopic as well as crystallographic techniques, whereas the structures and morphologies of H1-H3 are characterized by various spectroscopies and scanning electronic microscopy. Further, the electrocatalytic HER activity trend of H1 > H2 ≈ H3 is observed in 0.1 M phosphate buffer solution (pH = 7) through different electrochemical measurements, whereas the degradation processes of H1-H3 lead to their electrocatalytic deactivation in the long-term electrolysis as proposed by post operando analysis. Thus, this work is significant to extend the potential application of carbon electrode materials engineered with diiron molecular complexes as heterogeneous HER electrocatalysts for water splitting to hydrogen.

Heterogeneous polymer of aniline and benzoquinone enabled high energy density of graphene-based supercapacitors

Polyaniline and benzoquinone with powerful electrochemical activity and reversibility were widely used to boost specific capacitance of graphene electrode material and energy density of the corresponding supercapacitor devices. Inspired by these previous reports, herein, a novel heterogeneous polymer (polyAHQDME) containing both aniline units and benzoquinone ones were designed and synthesized, and finally grafted on reduced graphene oxide (rGO) framework. As expected, redox-active polyAHQDME modifier enabled rGO with an ultrahigh specific capacitance of 685.4 F g−1, five folds bare rGO counterpart. When assembled into symmetric two-electrode devices in quasi-solid-state aqueous and organic electrolytes, respectively, the key energy density parameter could reach as high as 21.6 and 100.6 Wh kg−1, outperforming most recently-reported modified carbon electrode materials.

MOF derived M/Sn/N (M= Mg, Mn) based carbon nanospheres as highly efficient multicomponent electrocatalysts towards hydrogen evolution and photovoltaics

Constructing multicomponent electrocatalysts towards efficient energy conversion is widely adopted strategy, in this regard, high performance metal/nonmetal codoped carbon electrode materials have attained great consideration. Still, the electroacatalytic susceptibility, abundant intrinsic active sites, and stable electrochemical performance in different electrolytes are considered as underline challenges, which can be addressed by rational structural modifications to build a hybrid electroactive material. In this work, unique Sn based multicomponent carbon nanospheres are firstly developed as highly efficient bi-functional electrocatalysts in solar cells and hydrogen evolution. The designed electrocatalysts feature the combined effect of dispersed bimetal active sites and sufficient nitrogen components within spherical carbon framework, which readily enhanced the charge transfer rate via multiple channels, boosting the triiodide reduction reaction (IRR) and hydrogen evolution reaction (HER). As a result, solar cell with Mn/Sn-NC based counter electrodes (CEs) exhibited an excellent power conversion efficiency (PCE) of 8.39 %, outperforming Pt (7.67 %). Moreover, superior HER kinetics are also demonstrated by Mn/Sn-NC with a small overpotential of 127.8 mV at 10 mA cm−2 and tafel slope of 77 mV dec−1. The rational design of the carbon nanospheres with MnSn2 bimetal nanoparticles and N doping promotes a high electrochemically active surface area, low charge-transfer resistance, excellent electrochemical stability, and superior electrocatalytic activity, providing a promising route to construct highly efficient materials towards multiple energy conversion applications.

A novel Au nanoparticles/ionic liquids/N‐ and P‐co‐doped carbon nanotubes‐modified carbon cloth sensor for the sensitive detection of adrenaline

AbstractAdrenaline (AD) is important in information transmission through the human central nervous system. Considering the significant biochemical functions of AD, the development of electrochemical sensors capable of detecting AD levels in living organisms has attracted considerable interest. In this study, AD was detected using electrochemical sensors developed based on Au nanoparticles/ionic liquids/N‐ and P‐co‐doped carbon nanotubes‐modified carbon cloth (AuNPs/ILs/N,P‐MWCNTs/CC) electrodes. AuNPs/ILs/N,P‐MWCNTs/CC composites were prepared on carbon cloth (CC) substrates using ionic liquids (ILs), N‐ and P‐co‐doped multi‐walled carbon nanotubes (N,P‐MWCNTs), and Au nanoparticles (AuNPs) as modified materials. The effects of pH and scanning speed were optimized and tested on the prepared composites. The results of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) experiments showed that the modified ILs, N,P‐MWCNTs, and AuNPs effectively improved the oxidation performance of AD. In addition, the linear range obtained from the DPV scans of the AuNPs/ILs/N,P‐MWCNTs/CC composite material was 30–505 μmol/L, with a detection limit of 0.31 μmol/L. The fabricated sensors have good sensitivity (6.9 μA·mM−1·cm−2) for AD of 30–505 μM. Therefore, the electrochemical sensing method based on the AuNPs/ILs/N,P‐MWCNTs/CC composite material is a promising and reliable AD detection technology that also exhibits good selectivity in the presence of interfering substances such as folic acid and ibuprofen. In practical applications, this material can help realize real‐time AD detection to determine whether athletes use doping and other illegal drugs before competitions and to perform synchronous detection.

3-Dimensional numerical study on carbon based electrodes for vanadium redox flow battery

Electrode materials are critical in determining the performance of Vanadium redox flow batteries (VRFB). This work aims at elucidating the difference between carbon-based electrodes for VRFB. The electrodes considered for the present study are Graphite felt, Carbon felt, Carbon paper, and Carbon cloth. To study the characteristic behavior of different electrode materials, a 3D unit cell numerical model was developed by coupling electrolyte flow and electrochemical reactions and mass transfer module apart from considering the electrode structural and material information such as porosity, permeability, thickness, conductivity, and specific area. The simulation results of this study suggest that the Graphite felt is the optimum choice as an electrode material for VRFB as it offers higher electrocatalytic activity, lower pressure drop, better performance, and lower cost. The study is also extended to a multilayer configuration of Carbon Paper and Carbon Cloth. The performance of multi-layered electrodes by stacking single sheets of Carbon Paper and Carbon Cloth electrodes are matched to meet the performance obtained with the Graphite felt electrode. It has been shown with the help of polarization curve and the pressure drop study that the performance of five layers of carbon cloth and nine layers of carbon paper match the performance of Graphite felt, approximately. The present study provides practical guidance for the design and optimization of VRFB electrodes.

Electrochemical performance of boron- and nitrogen-doped tetrahedral amorphous carbon

Tetrahedral amorphous carbon (ta-C) is one of the most versatile carbon electrode materials available. The incorporation of various dopants in ta-C alters the structural, electrochemical, physical, and chemical properties which are tunable for various applications. Furthermore, doped ta-C (ta-C:X) can be deposited on many different substrate materials (metals, ceramics, plastics) and geometries (micro-electrodes to ultra large areas at continuous coating lines). In this work, we present a comparison in electrochemical performance of ta-C electrodes prepared by filtered laser-arc (a physical vapor deposition process), doped with nitrogen (ta-C:N) at various levels, doped by boron (ta-C:B), and doped by boron and nitrogen together (ta-C:B:N). The ta-C:N films were doped via N2 gas in the deposition chamber, while ta-C:B and ta-C:B:N were deposited via incorporation of the dopant into the graphite cathode used for film synthesis. Films coated on silicon (Si) and titanium (Ti) substrates were compared through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The Fe(CN)63-/4− and Ru(NH3)63+/2+redox systems were used to investigate the electrochemical characteristics of each ta-C:X film type. Boron-doped diamond (BDD), glassy carbon (GC), and undoped ta-C were used as control electrodes. It was found that all ta-C:X films exhibited appropriate rates of electron transfer, wide working potential window (ca. 3.7 V in KCl), and low capacitance. Specifically, the boronated films produced high heterogenous rate constant (k), the lowest double layer capacitance (Cdl), and a consequentially smaller RC time constant than BDD and GC. Incorporating boron into undoped and nitrogenated ta-C films stabilizes the formation of sp3 bonded content during deposition leading to films with a smoother surface and increased hardness. It is shown that the B-incorporated films exhibit no compromise in their electrochemical performance despite the increase in sp3 content. Due to its versatile nature, ta-C stands out as a material with a wide range of tunable properties for various applications.

Evaluation of low-cost carbon/metal electrodes as cathodes and anodes in sediment microbial fuel cells

In the present study, influence of different anode and cathode materials including carbon felt, carbon cloth, and several metal electrodes with or without carbon cloth covering on sediment microbial fuel cell (SMFC) performance was investigated. Results suggested that stainless steel poorly performed as cathode electrode whereas it exhibited reasonable performance as anode. In SMFCs with carbon felt cathode, anodes including 400 series stainless steel mesh and 300 series stainless steel plate, both covered with carbon cloth, led to higher maximum power densities of 88 and 87 mW/m−2, respectively, compared with carbon felt, carbon cloth, 400 series stainless steel mesh, 300 series stainless steel mesh covered with carbon cloth, and copper plate covered with carbon cloth (power densities of 40, 74, 53, 68, and 47 mW/m−2, respectively). They also resulted in higher loss on ignition (LOI) removals of 9.4 % and 8.7 %, respectively. Cyclic voltammetry results showed that stainless steel plate covered with carbon cloth produced the highest redox current that was two times that of the carbon cloth. In addition, electrochemical impedance spectroscopy indicated lower charge transfer resistance in the SMFC with anodes including 400 series stainless steel mesh (20.6 Ω) and 300 series stainless steel plate (25.7 Ω), both covered with carbon cloth, compared to other anode materials. These findings suggest that stainless steel electrodes covered with carbon cloth provide SMFCs with improved electrochemical characteristics that enhance their electricity production and organic matter removal.

Nanoarchitectonics of porous carbon materials for supercapacitors using a strategy of direct mixing of biomass

Exploring biomass-based porous carbon electrode materials and regulating their pore structures remain a great challenge in the field of renewable energy storage devices. For our work, the mixture of bagasse and pleurotus geesteranus was used as carbon source, and a strategy based on the simple mixture of biomass was proposed to achieve the regulation of porous carbon structure. Through studying the co-pyrolysis process of the mixed system, a magic phenomenon that the lignocellulose of bagasse and the protein of the pleurotus geesteranus will have a Maillard reaction was found, promoting the pyrolysis of the mixed system. Since the degree of the pre‑carbonized carbon etched by KOH was different, the pore structure of the carbon material can be regulated by adjusting the mixing ratio. Through this regulation strategy, porous carbon with larger pore volume than bagasse based carbon materials was prepared as the carbon electrode for supercapacitors. The specific capacitance of 322.5 F g−1 was obtained by using three-electrode system in the solution of KOH at 0.5 A g−1. In the solution of Na2SO4, the energy density of two-electrode system can reach 21 Wh kg−1 at a power density of 872 W kg−1. Importantly, the simple preparation strategy provides an effective and green method to prepare advanced porous carbon electrode materials for high performance supercapacitor.

A review on porous carbon synthesis processes and its application as energy storage supercapacitor

In India, there is a plenty of biomass generating from the various sources like industry, agriculture etc. The thermochemical conversion output products are becoming more familiar in the field of energy storage like fuel cells, supercapacitors and batteries. Because of their high-power density and extended life cycle, supercapacitors are playing an increasingly significant role in the energy storage sector. Supercapacitors have seen many advances in recent years. The most popular electrode material for supercapacitors is carbon, and studying carbon is important for creating new kinds of supercapacitors. This article describes the materials usually utilized for carbon electrodes and the energy storage techniques of supercapacitors. The most widely used carbon materials and their uses in the field of supercapacitors are introduced in the section on carbon electrode materials. Ultimately, the trajectory of advancement for carbon-based supercapacitors is anticipated. Supercapacitors have made a lot of advancements lately. This paper describes the carbon production technologies, electrode preparation for the energy storage supercapacitor, electrolytes and various separators were discussed.

Cu-doped NiCo2S4/Kochia biomass porous carbon electrode material with high performance for hybrid supercapacitors

The suitable strategy combining metal doping and the introduction of porous carbon as a conductive substrate is proposed to address the shortcomings of the nickel‑cobalt sulfide (NiCo2S4) electrode material under development for supercapacitor energy storage. The multiplicative performance and cycle stability of NiCo2S4 have been significantly enhanced by the low cost and outstanding conductivity of copper (Cu) as a dopant. As well, the incorporation of Kochia biomass porous carbon (KAC-5), which has made it feasible to recycle waste biomass, into Cu-doped NiCo2S4 has effectively addressed the structural stability and electrochemical performance issues of NiCo2S4 electrode. The results showed that the introduction of Cu effectively optimizes the electrochemical properties by modifying the electronic state of the NiCo2S4 electrode to achieve the desired outcome. A composite material (Cu-NCS-10) was produced by adding KAC-5, due to the effects of KAC-5 on its geometry and electronic state, as well as its unique surface and structural characteristics, Cu-NCS-10 exhibits highly desirable energy storage. In comparison to the NiCo2S4 electrode, the Cu-NCS-10 electrode enhances specific capacity at 1 A·g−1 from 627C·g−1 to 754C·g−1, rate capability increased from 78.2 % to 88.1 % (1 A·g−1 to 10 A·g−1), and capacity retention after 5000 cycles from 75.9 % to 83.7 %. The electrochemical performance of the hybrid supercapacitor Cu-NCS-10||KAC-5 showed a wider voltage window, an energy density of up to 46.3 Wh·kg−1 at a power density of 775 W·kg−1, and maintenance of 80.9 % after 5000 cycles.

Nitrogen and Sulfur Co-doped Biomass-Derived Porous Carbon Electrodes for Ultra-High-Performance All-Aqueous Thermally Regenerative Flow Batteries.

Developing high-performance electrodes for the all-aqueous thermally regenerative ammonia battery (ATRB) system, serving as superior substitutes for commercial carbon cloth electrodes, is anticipated to enhance performance, yet it lacks effective guidance and research. In this work, theoretical analysis is initially used to evaluate the effective conversion and adsorption capacity of nitrogen and sulfur co-doped carbon with respect to copper ion by density functional theory calculation. On the basis of this concept, the nitrogen and sulfur co-doped biomass-derived porous carbon electrode (DGC) is prepared using natural porous carbon materials and thiourea. Compared with commercial carbon cloth electrodes, ATRB with DGC achieves a significant improvement in maximum power density of 49.2%. Via optimization of the doping conditions, the active sites can be effectively regulated to boost charge transfer at the reaction interface. Furthermore, the rapid charge transfer can match the excellent mass transfer performance, generating an impressive net power density of 847.5 W/m2.

Uncharged Monolithic Carbon Fibers Are More Sensitive to Cross-Junction Compression than Charged.

Textile-based wearable robotics increasingly integrates sensing and energy materials to enhance functionality, particularly in physiological monitoring, demanding higher-performing and abundant robotic textiles. Among the alternatives, activated carbon cloth stands out due to its monolithic nature and high specific surface area, enabling uninterrupted electron transfer and energy storage capability in the electrical double layer, respectively. Yet, the potential of monolithic activated carbon cloth electrodes (MACCEs) in wearables still needs to be explored, particularly in sensing and energy storage. MACCE conductance increased by 29% when saturated with Na2SO4 aqueous electrolyte and charged from 0 to 0.375 V. MACCE was validated for measuring pressure up to 28 kPa at all assessed charge levels. Electrode sensitivity to compression decreased by 30% at the highest potential due to repulsive forces between like charges in electrical double layers at the MACCE surface, counteracting compression. MACCE's controllable sensitivity decrease can be beneficial for garments in avoiding irrelevant signals and focusing on essential health changes. A MACCE charge-dependent sensitivity provides a method for assessing local electrode charge. Our study highlights controlled charging and electrolyte interactions in MACCE for multifunctional roles, including energy transmission and pressure detection, in smart wearables.

Green synthesis of oxygen-enriched tobacco stem-derived porous carbon via pre-oxidation and self-activation for high-performance supercapacitors

The use of agricultural and forestry waste to produce functional materials is a significant approach to achieving carbon neutrality. Herein, a green and cost-effective pre-oxidation and self-activation approach has been adapted to produce porous carbon from discarded tobacco stems for supercapacitors. The analysis of tobacco stem structure evolution reveals that the pre-oxidation process facilitated the cross-linked structure of the tobacco stem and the formation of KCl crystals, endowing tobacco stem-derived porous carbon with abundant micropores and high oxygen content during self-activation. The impact of pre-oxidation and self-activation temperature on the carbon structural characteristics of tobacco stems is systematically investigated. The optimized porous carbon exhibited a specific capacitance of 320 F/g at 0.5 A/g with good rate capability. Besides, it delivered a high energy density of 10.68 Wh/kg in a symmetrical supercapacitor. This work provides a green route for preparing carbon electrode materials for high-performance supercapacitors using agricultural and forestry wastes.

High performance hydrovoltaic devices based on asymmetrical electrode design

As a promising method for energy harvesting, water evaporation can generate electrical energy without additional mechanical energy input. In the evaporation power generation unit based on the principle of flow potential, the low charge collection efficiency is the key factor limiting the energy output, which limits the practical application of water evaporation equipment. Based on the principle of evaporation potential, an asymmetric sandwiched hydrovoltaic device based on metallic aluminum plate and carbon cloth electrodes is designed, which not only matches the electrode, but also reduces the carrier migration route and realizes fast charge transfer and collection. The device achieves an open-circuit voltage (Voc) of 730 mV and a short-circuit current density (Jsc) of 558 μA cm−2, capable of producing output power density exceeding 61.7 μW cm−2. Micro-nano electronic devices with low power consumption can be powered by integration of multiple devices. This study proposes a strategy for clean energy collection based on water evaporation.

Reducing Ohmic Resistances in Membrane Capacitive Deionization Using Micropatterned Ion‐Exchange Membranes, Ionomer Infiltrated Electrodes, and Ionomer‐Coated Nylon Meshes

Membrane capacitive deionization (MCDI) is an emerging water desalination platform that is compact, electrified, and does not require high‐pressure piping. Herein, highly conductive poly(phenylene alkylene) ion‐exchange membranes (IEMs) are micropatterned with different surface geometries for MCDI. The micropatterned membranes increase the interfacial area with the liquid stream leading to a 700 mV reduction in cell voltage when operating at constant current (2 mA cm−2; 2000 ppm NaCl feed) while improving the energy normalized adsorbed salt (ENAS) value by 1.4 times. Combining the micropatterned poly(phenylene alkylene) IEMs with poly(phenylene alkylene) ionomer‐filled electrodes reduces the cell voltage by 1000 mV and improves the ENAS values by 2.3 times relative to the base case. This reduction in cell voltage allows for higher current density operation (i.e., 3–4 mA cm−2) . The reduction in cell voltage is ascribed to the ameliorating ohmic resistances related to ion transport at the membrane‐process stream interface and in the carbon cloth electrode. Finally, porous ionic conductors are implemented into the spacer channel with flat and micropatterned IEM configurations and ionomer infiltrated electrodes. For the configuration with flat IEMs, the porous ionic conductor improves ENAS values across the current density regime (2–4 mA cm−2), while for micropatterned IEMs it gets improved only at 4 mA cm−2.

Tailored copper-based cathode design advances economic viability of electrocatalytic nitrate treatment with ammonia recovery in a scalable flow reactor

Electrocatalytic reduction is a promising alternative to remove nitrate (NO3–) from water and potentially recover value-added ammonia, but advancements are needed to reduce costs and promote technology adoption. Five monometallic catalysts on activated carbon cloth (ACC) electrodes were evaluated for electrocatalytic NO3– treatment in a previously developed scalable flow reactor. We report Cu and, for the first time, In (as In2O3) are the best performing catalysts regarding NO3– reduction activity (0.45–2.4 L gmetal–1 min–1), Faradaic efficiency (FE), and NH4+ selectivity, with intermediate NO2– accumulation using Cu and NH2OH using In. We discovered trace Pd addition (i.e., 0.01 wt%) to Cu eliminates NO2– accumulation, while approximately doubling activity, and boosting FE and NH4+ selectivity (99 %). Activity of Cu–Pd/ACC decreased with repeated treatment cycles but was easily recovered in situ via electrochemical regeneration. Electrocatalytic NO3– reduction costs with the Cu–Pd electrode were estimated less than IX or catalytic treatment, indicating economic viability.