Electrochemical Activity Research Articles

Prospects and challenges in electrochemical nitrogen activation for ammonia synthesis

Prospects and challenges in electrochemical nitrogen activation for ammonia synthesis

Boosting Electrochemical Performance via Extra-Role of La-Doped CeO2-δ Interlayer for "Oxygen Provider" at High-Current SOFC Operation.

Utilizing rare earth doped ceria in solid oxide cells (SOCs) engineering is indeed a strategy aimed at enhancing the electrochemical devices' durability and activity. Particularly, Gd-doped ceria (GDC) is actively used for barrier layer and catalytic additives in solid oxide fuel cells (SOFCs). In this study, experiments are conducted with La-doped CeO2 (LDC), in which the Ce sites are predominantly occupied by La, to prevent the formation of the Ce-Zr solid solution. This LDC is comparably used as a functional interlayer between the electrolyte and cathode if sintered at lower temperatures to avoid La2Zr2O7 impurity. In addition, the high substitution of La3+ into the ceria lattice improves the oxygen non-stoichiometry of LDC, leading to accelerated electrochemical high performance by the additional role of LDC for oxygen supplier capacitance at high current operation. Thus, it is confirmed that the improved SOFC high performance is achieved at the maximum power density (MPD) of ≈2.15W cm-2 at 800°C when the optimized LDC buffer layer is hired at the anode-supported typed-Samsung's SOFC by lowering the sintering temperature to prevent LDC's impurity reaction.

Dual modulation of homogeneous nanomaterialization and electrochemical activation enhancing zinc ion storage

Dual modulation of homogeneous nanomaterialization and electrochemical activation enhancing zinc ion storage

Manganese Sulfanyl Porphyrazine-MWCNT Nanohybrid Electrode Material as a Catalyst for H2O2 and Glucose Biosensors.

The demetallation reaction of sulfanyl magnesium(II) porphyrazine with N-ethylphthalimide substituents, followed by remetallation with manganese(II) salts, yields the corresponding manganese(III) derivative (Pz3) with high efficiency. This novel manganese(III) sulfanyl porphyrazine was characterized by HPLC and analyzed using UV-Vis, MS, and FT-IR spectroscopy. Electrochemical experiments of Pz3 conducted in dichloromethane revealed electrochemical activity of the new complex due to both manganese and N-ethylphthalimide substituents redox transitions. Subsequently, Pz3 was deposited on multiwalled carbon nanotubes (MWCNTs), and this hybrid material was then applied to glassy carbon electrodes (GC). The resulting hybrid electroactive electrode material, combining manganese(III) porphyrazine with MWCNTs, showed a significant decrease in overpotential of H2O2 oxidation compared to bare GC or GC electrodes modified with only carbon nanotubes (GC/MWCNTs). This improvement, attributed to the electrocatalytic performance of Mn3+, enabled linear response and sensitive detection of H2O2 at neutral pH. Furthermore, a glucose oxidase (GOx)-containing biosensing platform was developed by modifying the prepared GC/MWCNT/Pz3 electrode for the electrochemical detection of glucose. The bioelectrode incorporating the newly designed Pz3 exhibited good activity in the presence of glucose, confirming effective electronic communication between the Pz3, GOx and MWCNT surface. The linear range for glucose detection was 0.2-3.7 mM.

Template-Assisted Electrodeposited Copper Nanostructres for Selective Detection of Hydrogen Peroxide.

In this study, we demonstrate the electrodeposition of copper nanoparticles (NPs) on pencil graphite electrodes (PGEs) utilizing sodium dodecyl sulphate (SDS) as a soft template. The utilization of the surfactant had an impact on both the physical arrangement and electrochemical characteristics of the modified electrodes. The prepared Cu-SDS/PGE electrodes had hierarchical dendritic structures of copper NPs, thereby increasing the surface area and electrochemical catalytic activity in comparison with Cu/PGE electrodes. The Cu-SDS/PGE electrode showed excellent catalytic activity in reducing hydrogen peroxide, resulting in the sensitive and selective detection of hydrogen peroxide. The electrode exhibited a good sensitivity of 21.42 µA/µM/cm2, a lower limit of detection 0.35, and a response time of less than 2 s over a wide range spanning 1 µM to 1 mM of hydrogen peroxide concentrations. The electrodes were also highly selective for H2O2 with minimal interference from other analytes even at concentrations higher than that of H2O2. The approach offers the benefit of electrode preparation in just 5 min, followed by analysis in 10 min, and enables for the quantitative determination of hydrogen peroxide within 30 min. This can be achieved utilizing a newly prepared, cost-effective electrode without the need for complex procedures.

Investigation of ELectrochemical Behavior of Ferri/Ferrocyanide Redox on Carbon Paste Based Electrodes for Mercury (II) Electrochemical Sensor

The electrochemical characterisation of the materials used to make sensors is mostly based on the cyclic voltametry method. Cyclic voltametry is an electrical method for the dynamic study of electrochemical systems. Through a reversible potential sweep, the material is studied in contact with the ferri/ferrocyanide. Ferri/Ferrocyanide is one of the most studied chemical compounds in electrochemistry and photo-electrochemistry because of its singular known and controlled reactivity. The appearance of voltamorams and mathematical expressions make it possible to collect the information necessary for understanding the reaction. An electrode material is considered active if it shows a reversible peak in contact with the redox marker in cyclic voltametry. The mechanism of the reaction is also assessed using the peak potential difference ΔEp. The nature of the mass transport is determined by the anodic and cathodic peak current ratio Ipa/Ipc. The aim of this work is to compare the electrochemical activity of the Feri/Ferrocyanide couple achieved with carbon paste-based electrodes for application to the electrochemical sensor. The study of the peak potential difference ΔEp showed that the composition of the electrode material influences the reaction mechanism at the interface. Material transport and electronic charge transfer are impacted by complex phenomena. By studying the electrical quantities potential difference ΔEp, formal standard potential E° and current ratio Ipa/Ipc, the electrochemical sensors developed can be optimised.

Enhanced oxygen evolution reaction performance using amorphous hollow cerium-doped cobalt phosphate derived from ZIF-67 structures

A major obstacle in achieving massive operations water splitting is the slow rate of the anodic reaction. To address this issue, metal phosphates have been extensively employed as efficient materials for the oxygen evolution reaction (OER). In this study, ZIF-67 structures were synthesized in both single-metal and bimetallic forms with different molar ratios of cerium. The structure with the best electrochemical activity ((5 present) cerium doped ZIF-67 ((5)CeZIF-67)) was subjected to a phosphatization process, resulting in the formation of the amorphous and hollow cerium doped cobalt phosphate (Ce-CPO) structure as a novel and highly efficient OER electrocatalyst. To the best of authors knowledge, this is the first report on the synthesis and application of Ce-CPO structure for boosting OER process. This resultant structure exhibited suitable electrochemical performance in the oxygen evolution reaction (OER), achieving an overpotential of 286 mV at a current density of 30 mA cm−2 and a Tafel slope of 74.4 mV decade−1. Furthermore, the final structure demonstrated satisfactory stability during a 10 h operation period. The notable improvement in the Ce-CPO structure was due to the use of a bimetallic framework combined with phosphorus and an amorphous porous structure. The distinctive configuration achieved greatly amplifies the effective surface area, hence improving electron transfer. The findings of this research can contribute to the development of electrodes with improved performance in OER.

Co-Doping-Assisted Systematic Evolution of a Truncated Octahedral from Tetrahedral Cu2O for Enhanced Electrochemical OER Activity

Co-Doping-Assisted Systematic Evolution of a Truncated Octahedral from Tetrahedral Cu₂O for Enhanced Electrochemical OER Activity

Electrochemical Kinetics of LiFePO4 Cathode Material in Non-flammable Inorganic Liquid Electrolyte.

We unveil the fundamental insights of electrochemical kinetics of LFP cathode material and the passivation layer formation in the SO2-based non-flammable inorganic liquid electrolyte (IE). The influence of temperature and electrochemical potential cutoff in the electrochemical activity of LFP cathode and IE is disclosed. Furthermore, the materials compatibility, structural and chemical stability of LFP in IE is demonstrated using very slow galvanostatic cycling in combination with LiFePO4||Li0.1FePO4 symmetric cells. The lithium storage performance of LFP half-cell using inorganic electrolyte is presented with the optimum voltage window. LFP half-cells exhibit discharge capacities of 147, 111, and 75 mAh/g at 1, 4, 8 C rates, respectively, with coulombic efficiencies of ~99.98 %. The electrochemical behavior and mechanism of LFP||Graphite cell in IE is investigated while concurrently tracking the electrochemical potentials of LFP and Graphite half-cell.

Accelerated Electrons Transfer and Synergistic Interplay of Co and Ge Atoms (111 Crystal Plane) Activated by Anchoring Nano Spinel Structure Co2GeO4 onto Carbon Cloth Composite Electrocatalyst for Highly Enhanced Hydrogen Evolution Reaction

The electrochemical hydrogen evolution reaction (HER) was considered to be a promising strategy for future clean energy. In this work, a composite electrocatalyst (designated as CGO36@CC) was synthesized through anchoring of nano spinel structure Co2GeO4 onto carbon cloth fibers and exhibited outstanding electrocatalytic performance for HERs in an alkaline medium. The characterization outcome established that, after 36 h of hydrothermal reaction, nano spinel structure Co2GeO4 particles (exposed abundant 111 crystal planes) were stably loaded onto a carbon cloth fiber surface, and this structural configuration facilitated the electrons transferring between each other. In addition, the electrochemical analysis revealed that the incorporation of nano spinel structure Co2GeO4 and carbon cloth significantly augmented the electrochemical activity value of the composite and efficiently enhanced the HER performance. Notably, the overpotential was merely 96 mV at 10 mA·cm−2 current density, and the Tafel slope was only 48.9 mV·dec−1. Moreover, CGO36@CC displayed remarkable catalytic activity and sustained HER catalytic stability. The theoretical catalytic prowess of CGO36@CC stemmed from the collaborative influence of germanium and cobalt atoms within the exposed 111 crystal plane of the Co2GeO4 molecular framework. The amalgamation of Co2GeO4 with carbon cloth fiber conferred upon the composite electrocatalyst both superior theoretical catalytic activity and enhanced electron transfer capability. This work provides a novel strategy for exploring a highly efficient composite electrocatalyst combined transition metal with carbon material to accelerate the HER activity.

Unlocking interfacial effects in NiTiO3-TiO2 eutectic composite: Enhancing overall electrocatalytic and photoelectrochemical water splitting

This study introduces a novel approach to tackle the urgent demand for catalysts possessing both bifunctional capabilities and efficient photocatalytic properties. By employing the micro-pulling down method, a NiTiO3/TiO2 eutectic composite is synthesized, creating an interface rich structure. This composite is utilized as a photo-anode, displaying a significant photocurrent of 3.5 mA/cm2 at 1.4 V. Through annealing in an H2 atmosphere, the catalytic performance is finely adjusted, revealing distinct electrochemical activities at the interface of NiTiO3 and TiO2. Enhanced interfacial adsorption is confirmed by scanning electrochemical microscopy post-annealing. Remarkably, the annealed NiTiO3/TiO2 exhibits outstanding overall water-splitting efficiency, with minimal overpotentials of 80 mV (at 10 mA/cm2) and 120 mV (at 50 mA/cm2) for the HER and OER, respectively. The low Tafel slope (41 mV dec-1) underscores rapid water splitting kinetics. Density functional theory (DFT) calculations suggest that NiTiO3-TiO2 heterostructure can enhanced the catalytic properties of the surface providing higher adsorption of the electrolyte ions during catalytic reactions. This study establishes a straightforward crystal growth strategy for the design of highly effective, enduring, and bifunctional photocatalytic catalysts, signaling promising advancements in water splitting technology.

Phosphorization of α-Fe2O3 Boosts Active Hydrogen Mediated Electrochemical Nitrate Reduction to Ammonia.

Inexpensive iron-based materials are considered promising electrocatalysts for nitrate (NO3 -) reduction, but their catalytic activity and spontaneous corrosion remain challenges. Here, the α-Fe2O3 active surface is reconstructed by gradient phosphorization to obtain FePx with higher electrochemical activity. FeP2.0 optimizes the adsorption energy of NO3 - and its reduction intermediates, meanwhile promote the generation of active hydrogen (*H) but inhibit its generation of H2. More importantly, Fe and P can serve as binding sites for NO3 - and *H, respectively, which improves the electron utilization of NO3 - deoxygenation and the efficiency of the subsequent hydrogenation for the selective synthesis of NH3. 91.7% NO3 - conversion rate is achieved for the reduction of 100mL 200mg L-1 NO3 --N, 99.3% ammonia (NH3 selectivity (yield of 1.79 mg h-1 cm-2), and 91.4% Faraday efficiency in 3 h. The high-purity solid NH4Cl is finally extracted by gas extraction and vacuum distillation (81.4% recovery). This study provides new insights and strategies for the conversion of NO3 - to NH3 products over iron-based electrocatalysts.

Edge‐Enriched MoS2 as a High‐Performance Cathode for Aqueous Zn‐Ion Batteries

AbstractRechargeable aqueous zinc ion batteries (AZIBs) with the advantages in low cost, high safety, and environmental friendliness have broad application prospects in the field of energy storage. However, the slow diffusion kinetics of multivalent Zn2+ in materials make it hard to find a suitable cathode. Herein, HNO3 etched MoS2 with edge‐enriched feature is proved to be a promising cathode for high‐performance AZIBs. The highly exposed edges with superior electrochemical activity can not only offer more reactive sites for zinc storage but also facilitate electrolyte accessibility and shortens the ion transport pathway, thus accelerating reaction kinetics. As a result, the edge‐enriched MoS2 cathode exhibited higher specific capacity of 187 mAh g−1 at 0.1 A g−1 and outstanding cycling performance (89 % capacity retention after 700 cycles at 1 A g−1).

Synthesis and Redox Activity of Polyenaminones for Sustainable Energy Storage Applications

In the search for novel polymeric molecules that could be used as electroactive materials, seven novel polyenaminones were prepared in high yields by the transaminative polymerization of resorcinol-derived bis-enaminones with m- and p-phenylenediamine and with 2,5-diaminohydroquinone. The obtained polymers show very low solubility in organic solvents and absorb UV light and visible light at wavelengths below 500 nm. All the obtained polymeric products were tested for redox activity in a Li battery setup. The 2,5-diaminohydroquinone-derived compound showed the best redox activity, with a maximum capacity of 86 mAh/g and relatively good capacity retention, thus confirming the hydroquinone group as the primary redox-active group. Other potential redox-active groups, such as resorcinol and conjugated carbonyls, showed limited activity, while variations in the phenylene groups and the substitution of phenolic groups in the resorcinol residue did not impact the electrochemical activity of the polymers. Their electrochemical properties, together with their previously established chemical recyclability, make polyenaminones promising scaffolds for the development of materials for sustainable energy storage applications.

Композитные электроды на основе Li3V2(PO4)3, Li4Ti5O12 и углеродных нанотрубок : влияние состава, толщины и морфологии поверхности на электрохимические свойства

The influence of the composition, the thickness and the surface morphology of Li3V2(PO4)3 or Li4Ti5O12 based electrode composites with carbon nanomaterial and polyvinylidene fluoride on their electrochemical performance was examined. The thickness and the surface morphology of the electrodes were jointly controlled by rolling with different gaps and monitored using 3D laser microscopy and scanning electron microscopy. Increasing carbon nanomaterial content, the increase in the specific capacity of the electrode due to the non-Faradic component was observed up to the values of the specific capacity seemingly exceeding the theoretical capabilities of Li3V2(PO4)3 or Li4Ti5O12. When rolling the electrode with decreasing gap, we observed that Li3V2(PO4)3-based electrode composites improved their performance in terms of initial specific capacity and resistance to high current loads. As for Li4Ti5O12-based composites we observed the extremum. We concluded that not only the contact of Li4Ti5O12 or Li3V2(PO4)3 with electrolyte, but the three-phase contact of Li4Ti5O12 or Li3V2(PO4)3 with carbon nanomaterial particles and electrolyte as well was important for the electrochemical activity of electrode composites.

In-Situ Construction of Fe-Doped NiOOH on the 3D Ni(OH)2 Hierarchical Nanosheet Array for Efficient Electrocatalytic Oxygen Evolution Reaction.

Accessible and superior electrocatalysts to overcome the sluggish oxygen evolution reaction (OER) are pivotal for sustainable and low-cost hydrogen production through electrocatalytic water splitting. The iron and nickel oxohydroxide complexes are regarded as the most promising OER electrocatalyst attributed to their inexpensive costs, easy preparation, and robust stability. In particular, the Fe-doped NiOOH is widely deemed to be superior constituents for OER in an alkaline environment. However, the facile construction of robust Fe-doped NiOOH electrocatalysts is still a great challenge. Herein, we report the facile construction of Fe-doped NiOOH on Ni(OH)2 hierarchical nanosheet arrays grown on nickel foam (FeNi@NiA) as efficient OER electrocatalysts through a facile in-situ electrochemical activation of FeNi-based Prussian blue analogues (PBA) derived from Ni(OH)2. The resultant FeNi@NiA heterostructure shows high intrinsic activity for OER due to the modulation of the overall electronic energy state and the electrical conductivity. Importantly, the electrochemical measurement revealed that FeNi@NiA exhibits a low overpotential of 240 mV at 10 mA/cm2 with a small Tafel slope of 62 mV dec-1 in 1.0 M KOH, outperforming the commercial RuO2 electrocatalysts for OER.

Enhancing of hydroquinone and catechol oxidation using a graphite and graphene composite polymer modified paste electrode

ABSTRACT An innovative electrochemical redox response of hydroquinone (HQN) and catechol (CCL) was analysed using a bare graphite and graphene composite paste electrode (BGGCPE) and polymerised L-leucine modified graphite and graphene composite paste electrode (LCN-MGGCPE) was successfully developed in 0.2 M phosphate buffer solution (PBS) with pH 6.0 at a 0.1 V/s scan rate. Fabricated electrode using simple and cost-effective method, the polymerised LCN-MGGCPE surface shows more electrochemical activity, sensitivity and selectivity towards the determination for HQN and CCL. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), Differential pulse voltammetry (DPV), and electrochemical impudence spectroscopy (EIS) were utilised as analytical techniques while LCN-MGGCPE and BGGCPE surface characterisation were studied using a scanning electron microscopy (SEM) technique. LCN-MGGCPE exhibited superior electrochemical activity compared to BGGCPE towards the oxidation responses of both HQN and CCL. Additionally, the effect of pH studies, scan rate change for HQN, and concentration change of analyte molecule were examined, with the 0.025 to 0.500 V/s scan rate varied and revealing an adsorption-controlled process. The concentration changes of CVs methods ranged from 0.2 to 320 μM, DPVs ranged from 0.2 to 1100 μM and LSVs ranged from 0.2 to 850 μM, the calculated a limit of detection (LOD) of CV, DPV, and LSV, is 0.020 μM, 0.026 μM, and 0.011 μM and a limit of quantification (LOQ) of 0.068 μM, 0.088 μM, and 0.035 μM. The electrochemically developed LCN-MGGCPE shows good reproducibility, repeatability, stability, sensitivity and simultaneous analysis of analyte molecules were studied. This study presents a promising pathway for the growth of effective sensors for the determination of HQN in medicinal and water sample applications.

Manganese doped tailored cobalt sulfide as an accelerated catalyst for oxygen evolution reaction

Developing an efficient, robust, and noble metal-free electrocatalyst that can catalyse oxygen evolution reactions (OER) remains a significant challenge. CoS2, a representative of pyrite form transition metal dichalcogenides, has recently been identified as an economical catalyst. Here, an incredibly quick and scalable technique for novel catalysts synthesized with the use of the microwave method was introduced. Manganese-doped cobalt sulphide (Mn-CoS2) showed outstanding OER with a very low overpotential of 227 mV at 10 mA cm−2. Exposure of surface atoms resulted in high electrochemical activity, where the defects facilitated charge and mass transfer along the nanostructure, allowing surface dependent electrochemical reactions to be performed more efficiently. The electronic properties of pristine and transition-metal-doped CoS2 structures were also investigated using density functional theory (DFT). To better understand transition metal’s dependent impact on crystal structure, orbital electronic participation, charge density, and charge transformation in both pristine and Mn-dopedCoS2 frameworks were calculated and analysized. Our synthesis approach is primarily commercial and extensible, overcoming synthesis challenge of transition metal sulphide nanostructures with prime quality and implying a potential for commercial uses.

Lithium ion battery-assisted solar-driven water splitting

Electrocatalytic water splitting is an efficient strategy to substitute traditional fossil fuels with renewable energy H2. However, its scalable implementation, especially outdoors, has been hindered due to the lack of highly efficient and stable electrocatalysts and high-cost external electricity from the power grid. Here, we develop a hybrid nanostructure comprising N-doped carbon nanotube (NCNT) covalent-linked cobalt disulfide nanoparticles (CoS2-NPs) confined in hollow carbon nanocages (h-CoS@NC). As a bifunctional electrocatalyst for overall water splitting, the multi-heterostructure exhibits superior catalytic activities towards both hydrogen and oxygen-containing intermediates. Inspiringly, a two-electrode electrolyzer combined with the multi-heterostructure realizes a current density of 10 mA cm−2 at a low cell voltage of 1.58 V. When employing an anode of lithium ion battery (LIB), the h-CoS@NC delivers a high specific capacity of 1040 mAh g−1 at 0.1 A g−1 and maintains a considerable capacity of 648 mAh g−1, especially at rate of 5 A g−1. Furthermore, a large capacity of 582 mAh g−1 is achieved at 0.1 A g−1 for sodium ion battery. Moreover, theoretical calculations interpret that the enhanced electrochemical activities of h-CoS@NC should be attributed to the interaction between the CoS2 and carbon matrix, which effectively regulates the local electronic structures and weakens water adsorption/dissociation energies. As a proof-of-concept, a self-powered water splitting system integrating solar-charged lithium-ion battery with a water splitting electrolyzer achieves a steady H2 evolution rate at 0.4 A.

Unveiling electron transfer and radical transformation pathways in coupled electrocatalysis and persulfate oxidation reactions for complex pollutant removal

The degradation of multiple organic pollutants in wastewater via advanced oxidation processes might involve different radicals, of which the types and concentrations vary upon interacting with different pollutants. In this study, electrochemical activation of peroxymonosulfate (E/PMS) using advanced activated carbon cloth (ACC) as electrode was applied for simultaneous degradation of mixed pollutants, e.g., metronidazole (MNZ) and p-chloroaniline (PCA). 92.5 % of MNZ and 91.4 % of PCA can be degraded at the cathode and anode at a low current density and PMS concentration, respectively. The rate constants for the simultaneous removal of MNZ and PCA in the E/PMS/MNZ(PCA) system were 118 times and 6 times higher than those in the sole PMS system, and 2.5 times and 1.6 times higher than those in the E/Na2SO4/MNZ(PCA) system, respectively. Different electrochemical characteristics, EPR spectra and radical quenching tests verified that the degradation of MNZ and PCA in the optimal system proceeded primarily through non-radical-dominated oxidation, involving electron transfer and 1O2 effect. The system also exhibited low energy consumption (0.215 kWh/m−3·order−1), broad operational pH range, excellent removal efficiency for water matrix, and low by-products toxicity, indicating its strong potential for practical applications. The ACC, with its super stable, low cost, and electrochemical activity, make it as a promising materials applicable in the E/PMS system for degradation of multiple pollutants. The study further elucidated the mechanism of pollutant interaction with electrode materials in terms of radical and non-radical transformation, providing fundamental insight into the application of this system for treatment of complex wastewater.