Electrocatalytic Generation Research Articles

The Best of Both Worlds: Stacked Catalytic Layers for the Electrocatalytic Generation of CO in Zero-Gap Electrolyzers

Tailoring the properties of the catalytic layer (CL) alongside its architecture is a key development towards ensuring both improve efficiency and selectivity for CO2 electrolyzers. Traditionally, CLs for the CO2R consist of a single binder-material or a combination of them overtaking both the ion-conductance and maintenance of a hydrophobic environment.We herein decoupled these processes into two individual, stacked catalyst-containing layers. Specifically, a hydrophobic catalytic layer was herein placed on the GDL aiming to improve water management within the CL during CO2R in zero-gap electrolyzers, while A second catalytic layer bound by an ion-conducting binder allows for the conduction of OH- and HCO3-/CO3 2- during CO2R, improving both the ionic conductivity between the GDE and AEM as well as the mechanical adhesion between the different interfaces. Notably, we present the complete stepwise CL-optimization pathway, regarding both the single and segmented-CLs towards the CO2-CO conversion at current densities ≥ 300 mA cm2, highlighting the role of the operational parameters regarding scalability in different cell sizes and long-term stability > 100 h.

Electrochemical co-reduction of N2 and CO2 to urea using In2S3 anchored on S-doped reduced graphene oxide

The generation of urea by electrocatalysis using N2 and CO2 as feedstock is considered as a promising and green sustainable alternative to conventional energy-consuming industrial processes. Based on the existing studies, it was found that the effective adsorption and activation of N2 and CO2 on the catalyst surface is the primary condition for electrocatalytic generation, while the main by-product hydrogen evolution reaction (HER). Should be avoided as much as possible in order to improve the yield. In this paper, an In2S3-loaded electrocatalyst on sulfur-doped reduced graphene oxide for urea synthesis was designed and prepared with an average Faraday efficiency (FE) of 37.17 % and a urea yield of 7.24 mmol h−1 g−1, while maintaining long-term stability. In2S3@S-RGO has a unique porous structure of doped graphene, with continuous micron-sized pores that facilitate fast mass transfer, improve kinetic efficiency, and expand electroactive sites, thus enhancing the urea synthesis performance. Interestingly, the In2S3@S-RGO electrocatalyst not only exhibits excellent electrochemical performance, but also facilitates the adsorption and activation of reactants (N2 and CO2) due to the inhibitory effect of the indium-based material on HER. This work may provide new ideas for advanced catalysts to improve the efficiency of electrochemical synthesis of urea Faraday and to facilitate CN coupling applications.

Electrocatalytic Generation of Singlet Oxygen via ROS-Mediated Redox Chain Reaction for Efficient Disinfection.

The risk of harmful microorganisms to ecosystems and human health has stimulated exploration of singlet oxygen (1O2)-based disinfection. It can be potentially generated via an electrocatalytic process, but is limited by the low production yield and unclear intermediate-mediated mechanism. Herein, we designed a two-site catalyst (Fe/Mo-N/C) for the selective 1O2 generation. The Mo sites enhance the generation of 1O2 precursors (H2O2), accompanied by the generation of intermediate •HO2/•O2-. The Fe site facilitates activation of H2O2 into •OH, which accelerates the •HO2/•O2- into 1O2. A possible mechanism for promoting 1O2 production through the ROS-mediated chain reaction is reported. The as-developed electrochemical disinfection system can kill 1 × 107 CFU mL-1 of E. coli within 8 min, leading to cell membrane damage and DNA degradation. It can be effectively applied for the disinfection of medical wastewater. This work provides a general strategy for promoting the production of 1O2 through electrocatalysis and for efficient electrochemical disinfection.

The in-situ generation of ClO• by single- and dual-atom catalysis of chloride ions to degrade sulfonamide antibiotics: A DFT study

Single- (SACs) and dual-atom catalysts (DACs) are recognized as promising electrochemical materials. However, their application potential in the water treatment with the presence of chloride ions (the most common water matrice) still needs to be investigated. Thus, the first-principles calculation was used to investigate the electrocatalytic activation of Cl− and micropollutant degradation mechanisms by four kinds of metal-embedded nitrogen-doped carbon materials (M-N-C). The results show that the average Cl− adsorption energies (Eads) in different configurations follow the order of M2N6-a < M2N8 < MN4 < M2N6-b. The average Eads of SACs and DACs doped with different metal atoms follow the order of Fe < Co < Ni and Fe2 < FeNi < FeCo < CoNi ≈ Co2 < Ni2, respectively. The chlorine evolution reactions (CER) on the FeN4 and Fe2N6-a in neutral water were revealed as Cl− → *Cl → HClO* → free HClO, and HClO will rapidly generate ClO• to degrade target pollutants. The generated ClO• exhibits high reactivity towards sulfanilamide antibiotics (SAs) with the reaction rate constants of 1.78 × 108–6.86 × 109 M−1 s−1, indicating the high feasibility of ClO• in SAs purification from wastewater. This study provides mechanistic insights into the electrocatalytic generation of ClO• and its application in removing contaminants of emerging concern in M-N-C-supported electrochemical advanced oxidation processes.

Kraft lignin-derived multi-porous carbon toward sustainable electro-Fenton treatment of emerging contaminants

Reclaiming biomass waste to carbon cathode is promising to construct a sustainable electrochemical system. Here, we developed a novel thermal foaming process to reform kraft lignin to a free-standing and multi-porous carbon foam, which can be used as carbon cathode for electro-Fenton treatment of emerging contaminants (ECs). Benefiting from the excellent physicochemical and electrochemical properties with multi-porous and graphitic structure, the synthesized carbon foam cathode enhanced the electrocatalytic generation of H2O2 and •OH, and subsequently promoted the mass transfer and interactions among reactants (i.e., O2, H2O2, Fe2+, •OH, natural organic matters, and ECs). Eventually, an efficient degradation of ECs was achieved most likely via the multi-step •OH addition, cleavage, and ring opening reactions. Overall, the outcomes of this work provide a sustainable and applicable design and strategy to upgrade lignin-containing biomass to carbon cathode for efficient ECs remediation.

Modulating coal-derived carbon toward electrocatalytic generation of hydroxyl radicals for organic contaminant removal

Coal-derived carbon catalysts are modulated for producing hydroxyl radicals from oxygen gas to remove organic contaminants from water, and the roles of oxygen containing groups are explored, which would contribute to a greener society.

Comparative Analysis of Bioelectrocatalytic Cytochrome P450 3A4 Systems

This article describes the approaches developed by the authors with the aim to increase the efficiency of electro enzymatic reactions catalyzed by cytochrome P450 3A4. A comparative analysis of cytochrome P450 3A4 systems was carried out during the formation of the functional complexes hemoprotein-flavin nucleotides as low-molecular models of NAD(P)H-dependent cytochrome P450 reductase. The formation of a productive enzyme-substrate complex before the stage ofaccepting electrons from the modified electrode was studied from the electocatalytic viewpoint. Incorporation of the enzyme into nanopores of different nature on the electrode (2D-3D transition) was also studied. The results on the electrochemical reduction of bactosomes as the functionally active models of the microsomal monooxygenase system are also considered. The electrochemical and electrocatalytic parameters of cytochrome P450 3A4 were compared for different models of the electrocatalytic generation of metabolites.

Ferrocene as a Redox Catalyst for Organic Electrosynthesis

AbstractDespite substantial advancements in thermal and photochemical catalysis, the evolution of similar processes within the realm of organic electrochemistry has seen a slower pace. However, recent years have heralded a remarkable surge in molecular electrocatalysis. This innovative technique harnesses the power of molecular catalysts to expedite electrochemical transformations. This article underscores the application of ferrocene (Fc) as a redox catalyst in organic electrosynthesis. It delves into the extensive utilization of Fc in organic electrosynthesis, particularly emphasizing its role in the electrocatalytic generation and reactions of heteroatom‐ and carbon‐centered radicals, among various other reactions.

Novel trifunctional electrocatalyst of nickel foam supported Co2P/NiMoO4 heterostructures for overall water splitting and urea oxidation

The process of electrocatalytic water splitting for hydrogen generation is significantly limited by sluggish kinetics of the anodic oxygen evolution reaction (OER). The efficiency of H2 electrocatalytic generation can be improved by reducing the anode potential or substituting urea oxidation reaction (UOR) for oxygen evolution process. Here, we report a robust catalyst based on Co2P/NiMoO4 heterojunction arrays supported on nickel foam (NF) for water splitting and urea oxidation. In the hydrogen evolution reaction in alkaline media, the optimized catalyst Co2P/NiMoO4/NF displayed a lower overpotential (169 mV) at a large current density (150 mA cm−2) compared to 20 wt% Pt/C/NF (295 mV@150 mA cm−2). In the OER and UOR, the potentials were as low as 1.45 and 1.34 V. These values surpass (for OER), or compare favorably to (for UOR), the most advanced commercial catalyst RuO2/NF (at 10 mA cm−2). This outstanding performance was attributed to the addition of Co2P, which has a significant effect on the chemical environment and electron structure of NiMoO4, while increasing the number of active sites and promoting charge transfer across the Co2P/NiMoO4 interface. This work proposes a high-performance and cost-effective electrocatalyst for water splitting and urea oxidation.

Design of a Four-Atom Cluster Embedded in Carbon Nitride for Electrocatalytic Generation of Multi-Carbon Products.

The development of efficient and stable catalysts for the electrocatalytic CO2 and CO reduction reactions (CORR) is under active investigation, but the problems of poor selectivity and low efficiency for C2 products still exist. We design a two-dimensional carbon nitride material (C5N2H2) that contains an eight N-atom structure capable of coordinating four-metal atom clusters and supporting simultaneously two carbon oxide molecules needed for the C2 coupling. The designed material has excellent electrical conductivity and stability. After high-throughput screening of catalytic performance of multiple four-metal clusters embedded into the framework, we systematically investigate the CORR process of 11 candidates. We find that Cu4-C5N2H2 has superior selectivity and low limiting potential for generating ethylene, while Cu2Zn2-C5N2H2 is selective and efficient to synthesize ethanol. Further, we discover a novel type of descriptor related to 2D material flexibility to evaluate the potential-determining step for generating ethylene. Our report both broadens the possibilities for few-atom CO reduction and demonstrates a novel substrate flexibility-related descriptor to predict the catalytic performance of materials.

Merging electrocatalytic alcohol oxidation with C-N bond formation by electrifying metal-ligand cooperative catalysts.

Electrification of thermal chemical processes could play an important role in creating a more energy efficient chemical sector. Here we demonstrate that a range of MLC catalysts can be successfully electrified and used for imine formation from alcohol precursors, thus demonstrating the first example of molecular electrocatalytic C-N bond formation.This novel concept allowed energy efficiency to be increased by an order of magnitude compared to thermal catalysis. Molecular EAO and the electrification of homogeneous catalysts can thus contribute to current efforts for the electrocatalytic generation of C-N bonds from simple building blocks.

Electrocatalytic CO 2 Reduction over Bimetallic Bi-Based Catalysts: A Review

Electrocatalytic CO ₂ Reduction over Bimetallic Bi-Based Catalysts: A Review

Renewable Power for Electrocatalytic Generation of Syngas: Tuning the Syngas Ratio by Manipulating the Active Sites and System Design

AbstractAchieving decarbonization through zero net CO2emissions requires commercially viable application of waste CO2, throughout the transition to renewable and low‐carbon energy sources. A promising approach is the electrochemical carbon dioxide reduction reaction (CO2RR), which when powered with renewable electricity sources, provides a pathway for the conversion of intermittent renewable energy and waste CO2into value‐added chemicals and fuels. However, as CO2RR is accompanied by the competing hydrogen evolution reaction (HER) due to the presence of water, an opportunity is presented to generate a mixture of CO and H2, also known as synthesis gas or syngas – the building block of various oxy‐hydrocarbon products. The aim of this review is to analyze both Power‐to‐CO and Power‐to‐Syngas studies, in order to classify and discuss the active sites for both CO and H2generation through a new lens, providing insights into the structure‐activity correlations and facilitating the design of more active syngas electrocatalysts in the future. Through an evaluation of the economic viability of syngas generation, we determine that the carbon capture cost is a key parameter, with improvements in catalyst activity, catalyst impurity tolerance, and electrolyzer technology necessary for significant improvement in the economics of electrocatalytic syngas generation.

Electrocatalytic Generation of Acyl Radicals and Their Applications

AbstractIn this review, we highlighted the main achievements in the field of electrocatalytic generation of acyl radicals and their applications. These electrochemical strategies were introduced with an emphasis on the substrate scope, reaction limitation and underlying mechanism. The related reactions were categorized according to the pathways of acyl radical generation, including outer‐sphere electron transfer (ET), inner‐sphere ET, and hydrogen atom transfer (HAT) processes.

Thermally stable electro catalytic nickel-phosphide film deposition on graphite for HER electrode application

Deposition of nickel phosphide film is crucial in electronic fabrication industries as well as a hydrogen generating energy material. Accordingly, the film adhesion on various substrates like insulators (Al2O3, SiO2, etc.) or conductors (glassy carbon, graphite, transparent conductors-FTO etc.) is highly important, specially for printed circuit boards. It has technologically important properties wrt. high temperature thermally stablity, anti-corrosion, large wear resistance, and competitive over-potential wrt Pt metal (for fuel cell). We tackeled the challenge of depositing an adherent nickel phosphide (Ni-P) film on the graphite (GR) substrate by using economic electroless (EL) technique. Firstly, the GR surface was activated by thermal treatment of GR under O2 atmospheres, and obtained activated GR. Secondly, the EL precursor concentration was varied in the range of 0.1–0.2 M, to study its effect on Ni:P stoichiometry, structural phase and film thickness of Ni-P film on activated GR. Unlike on as recieved GR, activated GR showed film deposition due to the possible diffusion of O2 over the top layers of GR surface, during activation process. Such O2 diffusion led to an increased inter-planar distance & thus rendered favourable catalytic sites for Ni & P ions during EL deposition. This yeilds an adherent film of Ni3P phase after thermal treament, which is known to be themally stable beyond 1000 °C. Ni-P/GR film shows high potential application in (i) HER (hydrogen evolution reaction) for electro catalytic energy generation, and in (ii) graphite boat usable under elevated temperatures.

Interface Molecular Functionalization of Cu2O for Synchronous Electrocatalytic Generation of Formate.

The electrocatalytic generation of valuable fuels and chemicals from carbon dioxide (CO2) and others with the assistance of clean solar energy is a highly promising way to realize the carbon-neutral cycle, which invokes the systematic development of advanced electrocatalysts for efficient and selective redox reactions of feedstocks. Herein, we demonstrate the interface modification of cuprous oxide with polyvinylpyrrolidone (PVP) to improve the electrocatalytic efficiency for the synchronous formate generation. Density functional theory calculations reveal that the interfacial properties can be effectively regulated by the PVP functionalization for the favorable formation of intermediates to improve the selectivity of formate generation. Importantly, the advanced electrocatalyts enable an efficient coupling of CO2 reduction with methanol oxidation in an electrochemical cell powered with a solar cell. The work provides a predictive link between the electrocatalytic redox reactions by applying the interfacial regulation strategies of electrocatalysts.

Electrocatalytic Generation of Cathodic Luminol Electrochemiluminescence with Carbonized Polydopamine Nanotubes at a Low Positive Potential

Electrocatalytic Generation of Cathodic Luminol Electrochemiluminescence with Carbonized Polydopamine Nanotubes at a Low Positive Potential

Non-Calcined Layer-Pillared Mn0.5Zn0.5 Bimetallic-Organic Framework as a Promising Electrocatalyst for Oxygen Evolution Reaction.

Electrocatalytic generation of oxygen is of great significance for sustainable, clean, and efficient energy production. Multiple electron transfer in oxygen evolution reaction (OER) and its slow kinetics represent a serious hedge for efficient water splitting, requiring the design and development of advanced electrocatalysts with porous structures, high surface areas, abundant electroactive sites, and low overpotentials. These requisites are common for metal-organic frameworks (MOFs) and derived materials that are promising electrocatalysts for OER. The present work reports on the synthesis and full characterization of a heteroleptic 3D MOF, [Zn2(μ4-odba)2(μ-bpdh)]n·nDMF (Zn-MUM-1), assembled from 4,4'-oxydibenzoic acid and 2,5-bis(4-pyridyl)-3,4-diaza-2,4-hexadiene (bpdh). Besides, a series of heterometallic MnZn-MUM-1 frameworks (abbreviated as Mn0.5Zn0.5-MUM-1, Mn0.66Zn0.33-MUM-1, and Mn0.33Zn0.66-MUM-1) was also prepared, characterized, and used for the fabrication of working electrodes based on Ni foam (NF), followed by their exploration in OER. These noble-metal-free and robust electrocatalysts are stable and do not require pyrolysis or calcination while exhibiting better electrocatalytic performance than the parent Zn-MUM-1/NF electrode. The experimental results show that the Mn0.5Zn0.5-MUM-1/NF electrocatalyst features the best OER activity with a low overpotential (253 mV at 10 mA cm-2) and Tafel slope (73 mV dec-1) as well as significant stability after 72 h or 6000 cycles. These excellent results are explained by a synergic effect of two different metals present in the Mn-Zn MOF as well as improved charge and ion transfer, conductivity, and stability characteristics. The present study thus widens the application of heterometallic MOFs as prospective and highly efficient electrocatalysts for OER.

Electrocatalytic generation of hydrogen peroxide using carbon electrode modified with 5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone derivative. A green and efficient method

This work consists of three parts: in the first part, the electrochemical characteristics of 13-(4-nitrophenyl)-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone (NDXT), a newly synthesized compound was investigated in water/DMF solution using cyclic voltammetry, double potential step chronoamperometry and differential pulse voltammetry techniques. Based on the data obtained at this stage, a plausible mechanism for electrochemical behavior of NDXT was proposed. In the second part, the modification of the glassy carbon and carbon electrodes with NDXT was studied by different electrochemical techniques. In this part, the best conditions for covalent immobilization of NDXT on the electrode surface were determined and the immobilization mechanism of NDXT was discussed. Based on the results obtained at this stage, the modification of GC electrode was performed in a solution of NDXT and KNO2 in water (H2SO4, 1.2 M)/DMF (30/70, v/v) using cyclic voltammetry with a scan rate of 300 mV/s for 10 cycles between -0.1 and -1.0 V. In the third part, the electrochemical generation of H2O2 using modified NDXT carbon electrode, by reduction of dissolved O2 was studied. The results show that the modified cathode has good electrocatalytic activity in the production of hydrogen peroxide (461 mg/L). The effective parameters on the production of H2O2 including, current density, pH and cell design have been optimized. In this work, we developed a facile method for the electrocatalytic generation of hydrogen peroxide without using the metal catalyst, external H2 source and liquid-liquid extraction step which is a major improvement in comparison to the industrial anthraquinone based method.

Natural bamboo-derived O-doped rocky electrocatalyst for high-efficiency electrochemical reduction of O2 to H2O2

The in-situ H2O2 electrosynthesis by two-electron oxygen reduction reaction employing renewable electricity is a promising alternative to traditional anthraquinone process due to its security, environmental friendliness and excellent cost effectiveness, which requires high-performance, cost-effective and environmental-friendly electrocatalysts. A bamboo-derived O-doped rocky electrocatalyst is developed by facile pyrolysis and acid treatment for high-efficiency electroreduction of O2 to H2O2. Three-dimensional interconnected hierarchical pores in rocky electrocatalysts expose abundant electroactive sites and facilitate mass transfer of reaction species. From the results of rotating ring-disk electrode test, a H2O2 selectivity up to 80% and superior electrocatalytic activity of the prepared electrocatalyst are achieved by surface oxygen functionalization induced by acid treatment. At the optimal catalyst loading of 2 mg cm−2, prominent H2O2 productivity of 1037 mmol gcatalyst−1h−1 with high current efficiency up to 74.1% is achieved at 30 mA cm−2 by air-breathing cathode. Higher H2O2 productivity (1525 mmol gcatalyst−1h−1) is yielded by further raising the current density to 50 mA cm−2. Moreover, the durability test of the cathode through ten consecutive runs demonstrates its great stability for electrocatalytic generation of H2O2. This work inspires the development of promising biomass-derived electrocatalysts for green and sustainable on-site H2O2 electrosynthesis.