KOH Concentration Research Articles

Exploring Two-Dimensional MOF-Derived Co/Ni Species for Efficient Electrocatalytic Hydrogen Evolution Reaction

Hydrogen evolution reaction (HER) has received a lot of attention due to its promising advantages in producing “green hydrogen” via electrocatalysis with low cost and high efficiency. Until now, developing transition metal-based electrocatalysts for HER has been a great challenge. In this regard, we reported a facile strategy to fabricate Co/Ni species encapsulated by carbon structure (CoNi@C) through annealing two-dimensional (2D) metal-organic framework (MOF) nanosheets. The CoNi@C that was prepared under 600 °C achieved the highest catalytic performance in 1.0 M KOH electrolyte with an overpotential of 330 mV to acquire 100 mA cm−2. In addition, the effect of KOH concentrations on the HER performance of CoNi@C-600 was explored. In 3.0 M KOH electrolyte, the current density of 100 mA cm−2 has been attained at a bias potential of 80 mV. The alkaline environment can improve the electrocatalytic performance and further enhance the stability of the as-prepared catalysts. This work would endow promising opportunities for manipulating MOF-based structures through pyrolysis to fabricate highly efficient electrocatalysts.

Prediction, modeling, and optimization studies of eco-friendly gold extraction using alpha-cyclodextrin and the RSM and CCD methods

In the Democratic Republic of the Congo, gold extraction from ore in South Kivu utilized alpha-cyclodextrin (α-CD) as an eco-friendly method to replace harmful methods. Analysis of variance and response surface methodology were employed for prediction, modeling, and optimization studies. Atomic absorption spectroscopy revealed a 0.06% gold content in a randomly taken ore sample. Leaching with modified aqua regia was optimized with the following parameters: 7.27 h, 50 g/L HBr concentration, pH 1, and 200 rpm stirring speed, resulting in 98.5% removal. Neutralization tests with potassium hydroxide (KOH) followed leaching to prepare the solution medium with appropriate pH for extraction test, by varying parameters such as time, KOH concentration, and pH. Following neutralization, extraction tests with α-CD were carried out and optimized with the following parameters: 40 min, α-CD concentration of 11.6166 g/L, and a pH of 5, resulting in a percent removal of 98.9%. α-CD’s eco-friendly nature, cost-effectiveness, and high percent removal make it a promising and sustainable alternative for gold recovery, appealing to the mining industry.

Glass Surface Nanostructuring by Soft Lithography and Chemical Etching.

Due to its high durability and transparency, soda lime glass holds a huge potential for several applications such as photovoltaics, optical instrumentation and biomedical devices, among others. The different technologies request specific properties, which can be enhanced through the modification of the surface morphology with a nanopattern. Here, we report a simple method to nanostructure a glass surface with soft lithography and wet-chemical etching in potassium hydroxide (KOH) solutions. Glass samples etched with a polymeric mask showed a nanopattern with stripes of widths between 220 and 450 nm and modulated heights between 50 and 200 nm. For different solution concentrations or etching times, the obtained nanopatterns led to an increase or reduction of the water contact angle. The largest increment, ~20 degrees, was achieved by etching the glass for 180 min with 30% KOH concentration, while a super-hydrophilic glass (~9° contact angle) was achieved when etching for 90 min with the same concentration. Optical characterization showed a very low influence of the nanostructured pattern on glass transparency and an increment in UV transmittance for some cases.

Energy-conversion efficiency for producing oxy-hydrogen gas using a simple generator based on water electrolysis

Producing hydrogen efficiently through water electrolysis could greatly reduce fossil fuel consumption. As well as this renewable energy source will also help combat global warming and boost economic investment opportunities. This paper studied some factors affecting the performance of oxy-hydrogen/hydroxy (HHO) gas generator, such as applied voltage (from 10.5 to 13.0 V) and electrolyte solution concentration (from 0.05 to 0.20 M), using a dry fuel cell based on the electrolyzing technique of water. The results revealed that the HHO gas production rate, power consumption, and temperature change of electrolyte solution increased significantly with increasing the tested applied voltage and electrolyte concentration. This study concluded that the optimum conditions for producing HHO gas ranged from 11.5 to 12.0 V for applied voltage and from 0.05 to 0.10 M for KOH concentration according to the lowest specific energy and highest HHO gas generator efficiency. Under the previous optimum conditions, the highest productivity, specific energy, and efficiency of the HHO gas generator were 343.9 cm3 min−1, 3.43 kW h m−3, and 53.79%, respectively, using 12.0 V for applied voltage and 0.10 M for electrolyte solution concentration. These findings provide an unambiguous direction for adjusting the operational factors (applied voltage and electrolyte concentration) for efficient HHO gas production and use in different applications. Furthermore, the required energy to operate the HHO gas generator can be obtained from renewable sources.

Synergistic Interactions in a Heterobimetallic Ce(III)-Ni(II) Diimine Complex: Enhancing the Electrocatalytic Efficiency for CO2 Reduction.

In this study, we propose a practical approach for producing a heterobimetallic Ni(II)-Ce(III) diimine complex from an extended salen-type ligand (H2L) to serve as an electrocatalyst for CO2 reduction and demonstrate an outstanding overall efficiency of 99.6% of the cerium-nickel complex and integrate it into applicable cell assemblies. We optimize not only the catalyst, but the operational conditions enabling successful CO2 electrolysis over extended periods at different current densities. A comparison of electrochemical behavior in H-cell and zero-gap cell electrolyzers suggests potential applications for industrial scale-up. In the H-cell electrolyzer configuration, the most elevated efficiency in CO production was achieved with a selectivity of 56.96% at -1.01 V vs RHE, while HCOO- formation exhibited a selectivity of 32.24% at -1.11 V vs RHE. The highest TON was determined to be 14657.0 for CO formation, followed by HCOO- with a TON of 927.8 at -1.11 V vs RHE. In the zero-gap electrolyzer configuration, the most efficient setup toward CO production was identified at a current density (CD) of 75 mA cm-2, a flow rate of 10 mL min-1, operating at 60 °C and utilizing a low KOH concentration of 0.1 M to yield a maximum faradaic efficiency (FECO) of 82.1% during 24 h of stable electrocatalysis.

Photoelectroreduction CO2 to Ethanol Over BiFeO3 with Synergistic Effect of Self‐Polarization and External Electric Field

The exploitation of semiconductor self‐polarization is an effective mean of improving the efficiency of electron utilization. In this work, the synthesis of BiFeO3 (BFO) samples with varying photoelectric properties is achieved by modulating the concentration of KOH. The experimental results reveal that BFO‐4 (4 m KOH) has excellent carrier efficiency. Interestingly enough, the ethanol yield of up to 7.05 μmol cm−2 h−1 in the photoelectrocatalytic process, which is 1.4 times than that of single electrocatalysis. Based on the characterization data, the external electric field forms a multi‐electric field coupling in the BFO (external electric field can enhance the self‐polarization electric field), which enhances charge separation efficiency and facilitates surface reactions, and the CO2 reduction performance is improved. Finally, the free energy in the key step of CC coupling on the surface of BiFeO3 is calculated by DFT. This study offers a valuable reference for the application of ferroelectric materials in the photoelectrocatalytic reduction of CO2 and the design of catalysts for C2+ products.

Response surface optimization of a single-step castor oil-based biodiesel production process using a stator-rotor hydrodynamic cavitation reactor.

In order to combat environmental pollution and the depletion of non-renewable fuels, feasible, eco-friendly, and sustainable biodiesel production from non-edible oil crops must be augmented. This study is the first to intensify biodiesel production from castor oil using a self-manufactured cylindrical stator-rotor hydrodynamic cavitation reactor. In order to model and optimize the biodiesel yield, a response surface methodology based on a 1/2 fraction-three-level face center composite design of three levels and five experimental factors was used. The predicted ideal operating parameters were found to be 52.51°C, 1164.8rpm rotor speed, 27.43min, 8.4:1 methanol-to-oil molar ratio, and 0.89% KOH concentration. That yielded 95.51% biodiesel with a 99% fatty acid methyl ester content. It recorded a relatively low energy consumption and high cavitation yield of 6.09 × 105J and 12 × 10-3g/J, respectively. The generated biodiesel and bio-/petro-diesel blends had good fuel qualities that were on par with global norms and commercially available Egyptian petro-diesel. The preliminary cost analysis assured the feasibility of the applied process.

Role of Intermolecular Interactions in Deep Eutectic Solvents for CO2 Capture: Vibrational Spectroscopy and Quantum Chemical Studies.

Recent research and reviews on CO2 capture methods, along with advancements in industry, have highlighted high costs and energy-intensive nature as the primary limitations of conventional direct air capture and storage (DACS) methods. In response to these challenges, deep eutectic solvents (DESs) have emerged as promising absorbents due to their scalability, selectivity, and lower environmental impact compared to other absorbents. However, the molecular origins of their enhanced thermal stability and selectivity for DAC applications have not been explored before. Therefore, the current study focuses on a comprehensive investigation into the molecular interactions within an alkaline DES composed of potassium hydroxide (KOH) and ethylene glycol (EG). Combining Fourier transform infrared (FT-IR) and quantum chemical calculations, the study reports structural changes and intermolecular interactions induced in EG upon addition of KOH and its implications on CO2 capture. Experimental and computational spectroscopic studies confirm the presence of noncovalent interactions (hydrogen bonds) within both EG and the KOH-EG system and point to the aggregation of ions at higher KOH concentrations. Additionally, molecular electrostatic potential (MESP) surface analysis, natural bond orbital (NBO) analysis, quantum theory of atoms-in-molecules (QTAIM) analysis, and reduced density gradient-noncovalent interaction (RDG-NCI) plot analysis elucidate changes in polarizability, charge distribution, hydrogen bond types, noncovalent interactions, and interaction strengths, respectively. Evaluation of explicit and hybrid models assesses their effectiveness in representing intermolecular interactions. This research enhances our understanding of molecular interactions in the KOH-EG system, which are essential for both the absorption and desorption of CO2. The study also aids in predicting and selecting DES components, optimizing their ratios with salts, and fine-tuning the properties of similar solvents and salts for enhanced CO2 capture efficiency.

Enhanced electrocatalytic activity of Ni-Mn-Co-Fe alloys for efficient hydrogen and oxygen evolution reactions: A study on the effects of electrodeposition parameters

The synthesis of high-performance and cost-effective electrocatalysts for water splitting and fuel cell processes is crucial for hydrogen energy production and is considered one of the most significant challenges. This work produced a Ni‒Mn‒Co‒Fe electrocatalyst for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) via electrodeposition, which is a highly efficient and cost-effective method for synthesizing electrodes. The operating deposition parameters for Ni-Mn-Co-Fe were investigated, including the bath composition; scan rates of 5, 10, and 50 mV/s; pH values of 1.5, 3.5, and 7.5; bath temperatures of 25, 40, and 60 °C; and applied potentials ranging from −0.5 to −1.4 V vs. Ag/AgCl. The electrocatalytic activity of the electrocatalyst was evaluated at various temperatures and KOH concentrations. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) were employed to estimate the electrocatalytic activity. The electrocatalytic performance of various electrodes for the HER and OER in alkaline environments, including Ni, Ni‒Mn, Ni‒Co, Ni‒Mn‒Co, Ni‒Mn‒Fe, and Ni‒Mn‒Co‒Fe, was examined. The results indicate that the Ni‒Mn‒Co‒Fe electrode required overpotentials of 436 mV and 447 mV to achieve a current density of 100 mA/cm2 for the HER and OER, respectively, demonstrating outstanding electrocatalytic activity. Moreover, after 20 h of electrolysis at a current density of 100 mA/cm2, the overpotential changes were minimal (less than 4 %), indicating exceptional electrochemical stability. As a bifunctional electrode in the overall water-splitting system, a cell voltage of 1.57 V vs. RHE is required to deliver a current of 10 mA/cm2.

Adsorption of dibenzofuran by modified biochar derived from microwave gasification: Impact factors and adsorption mechanism

Dioxins, emanating from the waste incineration, constitutes an organic pollutant that poses considerable risks to the human health and environment. In this study, the corn straw char (CSC) and oak char (OC) derived from the electric heating or microwave gasification, and the coconut-shell activated carbon (AC) are employed as absorbents for the adsorption of dibenzofuran (DBF, dioxins model compound). Characterization techniques, including BET, X-ray CT, SEM-EDS, FTIR, and XPS, are performed to identify the DBF adsorption mechanism on the biochar. The results show that the biochar prepared by the microwave gasification has a more well-developed pore structure than that of the electric heating gasification. The higher porosity (16.94 %) and lower mineral content (1.75 %) are responsible for the effective adsorption of DBF onto AC. The adsorption capacity of CSC is proportional to the modified concentration of KOH. It is mainly ascribed to the decrement of carboxyl and lactone groups and the enhancement of alkaline functional groups on the biochar surface, which augments the hydrophobicity and π–π electron donor–acceptor (EDA) interaction. Instead, DBF adsorption capacity on the biochar is adversely affected by the HNO3 modification. For all biochar samples, the corresponding maximum adsorption ratios are AC (87.11 %) > KOH-modified CSC (77.14 %) > unmodified CSC (49.11 %) > unmodified OC (39.70 %) > HNO3-modified CSC (36.09 %). The adsorption mechanisms of DBF on the gasified biochar encompass the pore filling, hydrophobicity, and π–π EDA interaction. A desirable adsorption capacity of DBF on the biochar prepared by the microwave gasification is attainable through augmenting the specific surface area while diminishing the oxygen-containing groups of the surface simultaneously.

Comparative Studies on Methyl Ester Production from Pretreated Sludge Palm Oil Using Homogeneous and Heterogeneous Base Catalysts

A heterogeneous base catalyst transesterification process with a calcium oxide (CaO) catalyst was performed to produce high-purity methyl ester (ME) from pretreated sludge palm oil (PSPO) derived from sludge palm oil (SPO). Additionally, a comparative analysis was conducted with potassium hydroxide (KOH) as a homogeneous base catalyst to assess the distinctions between heterogeneous and homogeneous base catalysts. The response surface methodology (RSM) was utilized to determine the optimal and recommended conditions for both transesterification processes. For heterogeneous transesterification, a varying CaO catalyst loading (10–60 wt.%), methanol (25–65 wt.%), and reaction time (60–180 min) were essential parameters. Meanwhile, homogeneous transesterification involved investigating the KOH catalyst loading (1–3 wt.%), methanol (1.8–5.5 wt.%), and reaction time (20–60 min). For the heterogeneous-base-catalyzed reaction, the recommended conditions were as follows: a molar ratio of methanol to oil of 5.83:1 (41.61 wt.%), 31.3 wt.% CaO, and a reaction time of 119.0 min, which resulted in a ME purity of 96.51 wt.%. The optimal conditions for homogeneous transesterification were a molar ratio of methanol to oil of 0.49:1 (3.45 wt.%), a 40 min reaction time, and a 1.39 wt.% KOH concentration, which achieved 96.59 wt.% ME and met the standard.

Distribution and Diversity of Phytoplankton in Lake Alau, Maiduguri, Northeast Nigeria

The production of biodiesel from Thevetia peruviana seed oil using two different catalysts (NaOH and KOH) was evaluated. The Physical and chemical properties after extracting the seed oil were determined and the following results were obtained (density; 0.896g/cm3 , pH; 5.6, oil content; 32.5%, moisture content; 1.5%, specific gravity; 1.33, viscosity; 20mm2 /s, and refractive index; 1.48) and (Acid value; 0.3 mg of KOH/g, free fatty acid; 0.45%, iodine value; 38.5gI/100g, saponification value; was 75mg/KOH) respectively. Different catalysts were prepared by dissolving separately (0.18g. 0.20g and 0.21g) w% of NaOH and another 0.18g, 0.20, 0.21g w% of KOH pellets each in 10ml of methanol to produce concentrations of sodium and potassium methoxide respectively. Furthermore, Yellow Oleander Oil (YOO) was divided into 6 portions (25ml each) and poured into 6 different beakers (100ml) and separately placed on a magnetic stirrer. The amount of biodiesel produced at different concentrations of NaOH catalyst was 20.3ml, 20.1ml, and 22.3ml and the amount of biodiesel produced at different concentration of KOH were 24.2ml, 22.1ml, and 21.0ml. The conversion yield of the biodiesel catalysts was 81.2%, 80.4% and 89% for the NaOH catalyst and 96.8%, 88.4% and 84.0 for the KOH catalyst. The properties of the biodiesel such as flash point were 68℃, pour point was 3℃, cloud point was 7℃, cetane number was 98, the acid value was 0.5mg of KOH/g, density was g/cm3 , Iodine value was 3gI/100g, saponification value was 104, viscosity was 1.5mm2 s, the refractive index was 1.49. The results obtained from the study indicate that the physicochemical properties of the synthesized biodiesel are in agreement with the ASTM standard specifications. Both catalysts gave a considerable yield with KOH having a higher yield than NaOH in almost all the concentrations used. Thevetia peruviana can be considered a highly promising feedstock for biodiesel production.

Quantification of Deleterious Phase Precipitation in a Hyper Duplex Stainless Steel Aged at 700-950 °C Using Optimized Linear Sweep Voltammetry: Effect of KOH Concentration

Quantification of Deleterious Phase Precipitation in a Hyper Duplex Stainless Steel Aged at 700-950 °C Using Optimized Linear Sweep Voltammetry: Effect of KOH Concentration

Furandicarboxylic Acid (FDCA): Electrosynthesis and Its Facile Recovery From Polyethylene Furanoate (PEF) via Depolymerization.

Replacing fossil fuels with renewable, bio-based alternatives is inevitable for the modern chemical industry, in line with the 12 principles of green chemistry. 2,5-Furandicarboxylic acid (FDCA) is a promising platform molecule that can be derived from 5-hydroxymethyl furfural (HMF) via sustainable electrochemical oxidation. Herein, we demonstrate TEMPO-mediated electrooxidation of HMF to FDCA in ElectraSyn 2.0 using inexpensive commercially available electrodes: graphite anode and stainless-steel cathode, thereby avoiding the often cumbersome electrode preparation. Key parameters such as concentration of HMF, KOH, and catalyst loading were optimized by experimental design. Under the optimized conditions, using only a low amount of TEMPO (5 mol%), high yield and Faradaic efficiency of 96% were achieved within 2.5 hours. Moreover, since FDCA is a monomer of the bio-based poly(ethylene furanoate), PEF, we aimed to investigate its recovery by depolymerization, which could be of paramount importance in the circular economy of the FDCA. For this, a new polar aprotic solvent, methyl sesamol (MeSesamol), was used, allowing the facile depolymerization of PEF at room temperature with high monomer yields (up to 85%), while the cosolvent MeSesamol was recycled with high efficiency (95-100%) over five reaction cycles.

Delignification and enzymatic hydrolysis kinetics of KOH microwave-assisted pretreated banana stem for bioethanol production

Biomass pretreatment is essential to facilitate lignin removal and enhance cellulose concentration for optimal bioethanol production. Therefore, this research aimed to determine the effects of conventional KOH (KP) and Combined KOH microwave-assisted (CKMP) pretreatment on the banana stem (BS) composition, analyzing the kinetics of lignin removal at various temperatures and KOH concentrations for 25 min. Kinetics variables were calculated by fitting experimental data and cellulose was hydrolyzed to produce reducing sugars. The results showed that the highest lignin removal for KP and CKMP were 37.11%, and 40.39%, respectively, with CKMP having the lowest activation energy of approximately 2.688 kJ mol−1. CMCase and FPase activity were 1988.3474 and 1605.4187 U mL−1, respectively, which were significantly higher than the values reported in previous research. The maximum concentration of reducing sugars achieved was 17.69 g L-1, with an enzyme concentration of 50% (v/w), pH 5, and a hydrolysis duration of 25 h. Michaelis constant varied from 0.0037 to 0.0079, and the maximal rate ranged from 1.28 × 10−6 to 2.76 × 10−6 Mol L−1 s−1 when computing the reaction rate using the Michaelis–Menten kinetics model.

Integrating self-hygroscopic hydrogel electrolyte and porous electrode for supercapacitor operating in variable humidity environments

The application of supercapacitors (SCs) based on the conventional polyvinyl alcohol‑potassium hydroxide (PVA-KOH) polymer electrolyte is challenged in variable humidity environments, especially in low relative humidity (RH) environments. Herein, taking advantage of the high ionic conductivity and strong hygroscopicity of highly concentrated KOH solutions, we have prepared a hygroscopic hydrogel polymer electrolyte composed of sodium alginate (SA)/PVA/poly(acrylic acid) (PAA)-KOH. The SA/PVA/PAA-KOH gel electrolyte exhibits high ionic conductivity, superior water retention and even water adsorption capability. A three-dimensional CoCu-layered double hydroxide/zeolitic imidazole framework-67 (CuCo-LDH/ZIF-67) porous electrode has also been prepared for the construction of the high-performance SC operating in variable RH environments. The CuCo-LDH/ZIF-67 porous electrode allows deep penetration of the self-hygroscopic electrolyte, facilitating electron/ion diffusion and providing fast water transport channels. As a result, our asymmetric SC show significantly improved electrochemical performance than that of SC based on conventional PVA-KOH electrolyte under different RH environments. This integration strategy can advance the practical application of SC in extreme environments.

Luffa vines-derived N, O doped porous carbon with high surface area for supercapacitors

Considerable attention has been devoted to creating porous carbons with exceptional surface area and porosity from biomass waste for energy storage devices. Herein, we employed a straightforward high-temperature carbonization and KOH activation method to synthesize nitrogen (N) and oxygen (O) co-doped porous activated carbons derived from luffa vines (LVACs). The impact of varying KOH concentrations on the morphology, structure, and electrochemical properties of LVACs was thoroughly investigated. The optimal mass ratio of KOH to LVACs at 1:6 achieved the maximum specific surface area of 3369 m2 g−1. At a current density of 1 A g−1, the LASC-6 electrode exhibits an impressive specific capacitance of 348.5 F g−1. It also demonstrates exceptional rate performance, retaining 70.6 % of its capacitance at a current density of 20 A g−1. The electrode possesses robust cycling stability, retaining 90 % of the initial capacitance after 5000 cycles. We assessed the practicality of LVAC-6 by constructing symmetric supercapacitors (SSCs) using KOH and [BMIM]BF4 electrolytes. The KOH and [BMIM]BF4 SSCs achieved specific capacitances of 86.75 and 50.31 F g−1, respectively, at a current density of 0.25 A g−1. Moreover, the [BMIM]BF4 SSC exhibited an impressive energy density of 51.05 Wh kg−1 at a power density of 346.15 W kg−1. Therefore, we propose a simple and cost-effective strategy to produce porous carbon materials with excellent electrochemical performance from discarded biomass waste, facilitating the preparation of environmentally friendly electrode materials for high-performance supercapacitors.

Construction of 2D/1D rGO/H2Ti3O7 composite as anode for high performance lithium-ion batteries

Ultrafine one-dimensional (1D) H2Ti3O7 nanowires were prepared by a hydrothermal reaction with high concentration of KOH as base source. Then 2D/1D rGO/H2Ti3O7 architecture was constructed and investigated as the anode material for lithium-ion batteries. Benefiting from the addition of rGO nanosheets and the retention of ultrafine 1D H2Ti3O7 nanowires, the rGO/H2Ti3O7 electrode presented superior electrochemical performance with excellent rate capability, long cycling stability and high capacity in half cells. It delivered high reversible capacities of 274 mAh g−1 at 0.1 A g−1 and 163 mAh g−1 at 1 A g−1, as well as a long-term cycling performance (259.3 mAh g−1 at 0.2 A g−1 after 1000 cycles). The excellent electrochemical performance of the composite can be attributed to the unique architecture with smaller diameter of 1D H2Ti3O7 nanowires and conductive rGO nanosheets to shorten the transmission distance of electrons and Li+ and improve the electrical conductivity in rGO/H2Ti3O7 composite.

A novel design of urea-assisted hydrogen production in electrochemical-chemical decoupled self-circulating systems.

In traditional water electrolysis processes, the oxidation and reduction reactions of water are coupled in both time and space, which presents significant challenges. Here, we propose an optimized design for an electrochemical-chemical self-circulating decoupled system. This system uses the continuous Ni2+/Ni3+ redox process on nickel hydroxide electrode sheets to stepwise couple the urea oxidation-assisted hydrogen production system, separating the hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) into two distinct steps: electrochemical and chemical reactions. In the first electrochemical step, water is reduced at the cathode to produce hydrogen, while the single-electron electrochemical oxidation of Ni(OH)2 at the anode generates NiOOH. Then, in the second chemical reaction step, NiOOH spontaneously oxidizes urea, causing its decomposition and simultaneously reducing back to the Ni(OH)2 state. We concurrently investigated the effects of temperature and OH-concentration on the spontaneous oxidation of urea. At 80 °C and with a 1 M KOH concentration containing 50 mg of urea solution, the NiOOH electrode successfully catalyzed the spontaneous decomposition of urea, achieving conversion rate of 100% and faradaic efficiency of 98%.

Effect of deposition potential and KOH concentration on ethanol oxidation reaction with Pd nanoparticles electrodeposited on glassy carbon from reline

Pd nanoparticles (PdNPs) are deposited electrochemically on the glassy carbon electrode surface using PdCl2 dissolved in a deep eutectic solvent composed of choline chloride and urea (reline). The morphology and particle size of the PdNPs are determined from SEM exhibiting a homogeneous distribution with potential deposition depending on particle size. The particles display a core-shell morphology, consisting of Pd(0) as the core and Pd(OH)2 as the shell. The ethanol oxidation reaction, EOR, is evaluated at different KOH concentrations. The electrocatalyst with the highest mass activity is achieved at −750 mV potential deposition and 1 M KOH, exhibiting 3126 ± 606 mAmgPd−1. However, when 0.1 M KOH is used the mass activity decreases to one-third the value obtained at 1 M KOH. Notwithstanding, the mass activity displayed by these PdNPs is superior to that reported for other Pd-based nanoparticles synthesized using more complex, time-consuming and costly methods reported in the literature.