Electrochemical Reduction Method Research Articles

A thin LiGa alloy layer from in-situ electroreduction to suppress anode dendrite formation in lithium-sulfur pouch cell

Lithium metal is considered to be the “Holy Grail” of battery anodes. However, the inhomogeneous deposition of lithium ions on the anode surface readily generates lithium dendrites, which leads to severe hidden danger. Particularly in lithium-sulfur batteries, the insulated Li2S caused by the reaction of lithium and polysulfide lithium aggravates the one-dimensional deposition of lithium ions. Meanwhile, the corrosion of lithium metal is the main reason for the decrease in lithium-sulfur capacity. Anodes made from alloys are an effective solution, while they sacrifice energy density. Here, we adopted an in-situ electrochemical reduction method for fabricating a very thin, low-resistance, low-reactivity LiGa alloy layer with uniform Li deposition sites on the Li metal surface in order to suppress side reactions with sulfides and dendrites. Furthermore, excellent electrochemical kinetics, high specific capacity, and high stability are also obtained in lithium-sulfur batteries with the LiGa layer. The alloy layer-based cells delivered a long cycle lifespan and a high capacity under high sulfur-loading, low Electrolyte/Sulfur ratio (5.0 µL mg−1) and thin lithium flakes (50 µm). This surface regulation engineering could be applied to the high-load systems and pouch cells, which provides a new solution for the prospect of industrialization.

Solvation and Stability in Lithium-Mediated Nitrogen Reduction

The lithium-mediated method of electrochemical nitrogen reduction, pioneered by Tsuneto et al1 then verified by Andersen et al2, is currently the sole paradigm capable of unequivocal electrochemical ammonia synthesis. Such a system could allow the production of green, distributed ammonia for use as fertiliser or a carbon-free fuel. However, despite great improvements in Faradaic efficiency and stability since just 20193, fundamental understanding of the mechanisms governing nitrogen reduction and other parasitic reactions is lacking.Lithium Ion Battery (LIB) research can provide insight; since both lithium-mediated electrochemical ammonia synthesis and LIBs utilise an organic solvent and lithium salt, both form a Solid Electrolyte Interphase (SEI), which is electronically insulating but ionically conducting, at the electrode surface. In LIBs, this is necessary to stabilize and cycle low potential materials4. In lithium-mediated ammonia synthesis, the SEI could also have a critical role in controlling the access of protons and other key reactants to the catalytically active sites and promoting greater selectivity toward nitrogen reduction to ammonia5. While some characterisation of the SEI has been carried out for the lithium-mediated nitrogen reduction system6, the literature still lacks holistic studies which aim to carefully characterise the bulk electrolyte and SEI components and link them to system performance.In this work we use insight from battery science to tackle a significant stability problem in lithium-mediated nitrogen reduction. The traditional electrolyte employed by Tsuneto et al. was 0.2 M LiClO4 in a 99:1 tetrahydrofuran to ethanol mix. While this system can produce ammonia, the working electrode potential becomes more negative over time. Our initial investigations show that this problem stems from an unstable SEI which becomes increasingly organic. Simply by raising the concentration of LiClO4 in the electrolyte, we vastly improve stability, as shown in figure 1(a), and boost Faradaic efficiency. Bulk electrolyte salt solvation properties are investigated through Raman spectroscopy, as shown in figure 1(b). Here we observe the emergence of a shoulder at around 930 cm-1 with increasing LiClO4 concentration, which we assign to the emergence of Contact-Ion-Pairs (CIPs) through comparison to Density Functional Theory calculations. These CIPs mean that perchlorate anion degradation products are more abundant in the formed SEI, as shown in our X-Ray Photoelectron Spectroscopy and Time-of-Flight Secondary Ion Mass spectrometry results. This more inorganic SEI protects the electrolyte against further degradation, preventing the working electrode drift to more negative potentials. We then link this behaviour to a peak observed in the Faradaic efficiency of ammonia synthesis at 0.6 M LiClO4 by also considering decreasing N2 solubility and diffusivity, as well as a more ionically conductive SEI, in an increasingly concentrated electrolyte. We also present never-before seen cross-sectional images of the SEI using cryogenic Focussed Ion Beam milling and Scanning Electron Microscopy, further aiding understanding of how salt solvation affects the morphology of the formed SEI and system performance. Our results emphasise the need to consider SEI properties in electrolyte design for lithium-mediated nitrogen reduction, as well as the need to balance desirable SEI properties with desirable bulk electrolyte properties. Tsuneto, A., Kudo, A. & Sakata, T. Efficient Electrochemical Reduction of N 2 to NH 3 Catalyzed by Lithium . Chemistry Letters vol. 22 851–854 (1993).Andersen, S. Z. et al. A rigorous electrochemical ammonia synthesis protocol with quantitative isotope measurements. Nature 570, 504–508 (2019).Westhead, O., Jervis, R. & Stephens, I. E. L. Is lithium the key for nitrogen electroreduction? Science. 372, 1149–1150 (2021).Peled, E. & Menkin, S. Review—SEI: Past, Present and Future. J. Electrochem. Soc. 164, A1703–A1719 (2017).Singh, A. R. et al. Electrochemical Ammonia Synthesis—The Selectivity Challenge. ACS Catal. 7, 706–709 (2017).Li, K. et al. Enhancement of lithium-mediated ammonia synthesis by addition of oxygen. Science. 1597, 1593–1597 (2021). Figure 1

Synthesis of Graphene based nanocomposites and their application – A Review

There are two categories in the graphene preparations which are top-down and bottom-up methods. Top-down methods consist of mechanical exfoliation, chemical exfoliation and chemical synthesis reduction. Meanwhile, chemical vapor deposition (CVD), pyrolysis and epitaxial growth synthesis under bottom-up methods. Graphene has its own limitation and unsuitable for certain applications. Thus, functionalizing the graphene with selected molecules and nanomaterials may result in graphene functionalized nanomaterials that improve the feature of the graphene. Many methods can be done to synthesise graphene based on nanocomposites and cab be divided into two types which are in-situ methods and ex-situ methods. Hydrothermal methods, electrochemical deposition methods and reduction methods are categorized in in-situ methods, while covalent interaction and non-covalent interaction are categorized in ex-situ methods. Application of graphene based nanocomposite on biosensor and supercapacitor is discussed in this review paper.

Electrolytic Recovery of Metal Cobalt from Waste Catalyst Pickling Solution.

Terephthalic acid production plant uses liquid cobalt–manganese bromide as a catalyst. The waste catalyst is burned with exhaust gas and accumulated in fly ash, which is further pickled and impregnated with a sulfuric acid solution. The resultant solution is rich in cobalt and manganese metal ions with few metal impurities from other petroleum raw materials. An electrochemical reduction method is used to recover cobalt metal from the waste catalyst fly ash pickling solution of terephthalic acid. Various steps have been taken to remove impurities and extract and separate the required pure cobalt metal solution. Afterward, the process of electrolytic reduction smelting is conducted. Variables investigated include current density, electrolyte pH, electrode materials, and electrolytic cell diaphragms, among several others. Results show that the product purity can reach up to 99.84% for the electrolyte feed composition of 21.4 g L−1 Co, 38.2 g L−1 Na, and 2.02 g L−1 Mg.

Sustainable Synthesis of Dual Single‐Atom Catalyst of PdN4/CuN4 for Partial Oxidation of Ethylene Glycol

AbstractCatalysts assumed that properly designed bimetallic systems would provide superior catalytic performance due to the cooperative effects between two atoms. Dual single‐atom catalyst (DSAC) PdN4/CuN4 is synthesized using a simple, cost‐effective, and efficient electrochemical reduction method. The palladium single‐atom is prepared first by electrochemical reduction of copper phthalocyanine to create defective N4 sites. The new structural feature is characterized by copper reduction from Cu‐N4 coordination and the formation of defected N4 (▫M‐N4) sites, which react with a Pd precursor and form PdN4 on the host surface. The DSAC PdN4/CuN4 technique synergistically improves electrocatalytic performance toward the ethylene glycol oxidation reaction. It possesses excellent glycolate selectivity (above 88%) in an alkaline solution with an onset oxidation potential as low as 0.6 V versus a reversible hydrogen electrode, compared to commercial Pd/C. The DSAC electrocatalyst is characterized by its high current density of 83.92 mA cm−2 and high faradic efficiency value (>80%) for glycolate at 1.0 VRHE. The findings suggest a promising method to synthesize the DSACs in varying transition metals to achieve highly efficient, selective, and environmentally friendly catalysts for different applications.

Quantitative Oddy test by the incorporation of the methodology of the ISO 11844 standard: A proof of concept

• '3 in 1′ Oddy test was used to evaluate harmful materials for metallic cultural heritage. • Unlike the original Oddy test setup, metal coupons were hung from glass hooks. • Quantitative evaluation of Oddy test was performed as a complement to the visual rating. • Electrolytic cathodic reduction for silver and copper and mass gain for lead. • Quantitative methods allow selecting the safest material from those rated as suitable. The Oddy test is a preventive conservation tool that helps to preserve real objects of cultural significance. To do this, it uses silver, copper and lead coupons as corrosion dosimeters. Despite its utility and extensive experience, one of its limitations is the lack of a quantitative assessment method to avoid the subjectivity of visual examination and numerically rank the tested materials into suitable (permanent or temporary) and unsuitable. To address these issues, we present a proof of concept for the incorporation of the methodology of the ISO 11844-2 standard into the assessment stage of the '3 in 1′ Oddy test. And so, use standardized quantification methods of corrosion rate for metal coupons such as electrochemical reduction for silver and copper coupons and gravimetric methods for lead coupon. A traditional '3 in 1′ Oddy test has been performed to evaluate four materials known for their harmful nature to metallic cultural heritage: oak wood, medium density fibreboard (MDF), wool and leather. The electrochemical reduction method yields excellent results for copper and silver, allowing quantifying the corrosion even for the lightest tarnishing of the metal coupons that act as control or reference. For example, in the absence of contaminant-emitting material, the silver coupon lost 0.12 nm of thickness due to corrosion of the own conditions of the Oddy test (60 °C and 100%RH). Mass gain is also a convenient method with enough sensitivity to rank the corrosion of lead. It has been shown that the ranking established by visual inspection alone can be misleading, rating similarly materials that produce large differences in corrosion rates. Moreover, in the case of copper, the visual rating of the tested materials does not agree with that obtained from electrochemical reduction. Further research is needed to establish the limits of this methodology, but results presented here demonstrate the feasibility and utility of this approach.

Effect of Dual-Flow Channel Structures on Electrochemical CO2 Reduction in Proton Exchange Membrane Electrolyzers

Greenhouse gases such as carbon dioxide and methane are responsible for intensifying global warming. Consequently, a reduction in power plant outputs and an increase in capture and storage on-site are required to reduce greenhouse gas emissions. Recently, research has focused on an electrochemical CO2 reduction method because the amount of CO2 reduction can be controlled by adjusting the operating voltage. However, to scale up the electrochemical system while maintaining a high conversion rate in a large cell, a suitable flow field of the cell must be optimized. The transparent cell structure presented in this study allows visualization of the distribution of the two-phase flow. Accordingly, dual-flow channels consisting of main and sub-channels have been designed. Furthermore, multiple configurations of the dual-flow channels and locations of the catalyst layer have been compared. The interdigitated sub-channels and inverted layered cell structures can supply gas and liquid to the catalyst layer via distinct pathways, allowing for uniform flow distribution to each channel.

Conversion of Carbon Dioxide into Value Added Chemicals Using Electrochemical Reduction Method on Supported Bimetallic Catalysts

Currently, many studies reveal that the level of carbon dioxide in the atmosphere is rising continuously and disrupt the environment due to its cause for global warming. For this reason, advanced and emerging technologies associated with conversion of CO2 are highly essential. Among many of the methods, electrocatalytic reduction of CO2 is the most efficient and easy way to reduce CO2 into CO, alcohols, hydrocarbons and other products. Bimetallic nanoparticles of Au and Cu and the parent monometallics of each metal are synthesized and supported on functionalized multiwalled carbon nanotubes (MWCNT). The supported bimetallic nanoparticles are dispersed uniformly on fiber carbon papers (CP). To evaluate and correlate the performance of the reduction, tuning the size and structural properties of AuCu electrocatalyst are investigated by incorporating polyvinylpyrrolidone (PVP) for electrochemical reduction (ECR) of CO2. Different amounts of PVP are applicable for each bimetallic and monometallic electrocatalysts (AuCu/MWCNT/CP, Au/MWCNT/CP and Cu/MWCNT/CP). The significant role of PVP on the atomic distribution of AuCu nanoparticles (NPs) and its particle size have been studied in advance. X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) are key measurements to estimate the alloying extent of Au Cu in the alloy including the coordination numbers of each metal. The electrocatalysts, which are prepared with PVP, have a better activity and selectivity compared to the bimetallic synthesized without PVP. The amount of PVP affects the structure and significantly minimizes the size of NPs that influences the activity and selectivity of products. At -0.91 V vs. RHE, the faradaic efficiency (FE%) of CO using AuCu/CNT (1.5 g PVP) was around 88%, but in the absence of PVP, the same test resulted in ~71%, indicating the effect of PVP in the product selectivity.

Effect of Milling Time and PCA on Electrode Properties of Cu2O-ZnO/C Catalyst Alloy used on Electrochemical Reduction Method of CO2

Carbon dioxide is one of the greenhouse gases that cause climate change, thus the effort for reducing the concentration of CO2 necessary, for example through the conversion of CO2. The conversion of CO2 into methanol plays important role, because in addition to reducing greenhouse gas, it is also creating a future energy carrier needed in fuel cell technology. One of the CO2 conversion methods is the electrolysis method using MEA. The electrochemical CO2 conversion in this study used a Cu2O-ZnO/C composite catalyst made by milling methods at various milling times, as well as the effect of PCA utilization. The catalysts were characterized using Particle Size Analyzer (PSA), Brunauer-Emmett-Teller (BET), Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and SEM-EDX analysis. The results of PSA and BET characterization showed that the longer the milling time, the smaller the particle size and the higher the relative surface area. The use of PCA increased the unoxidized Cu content as indicated by the SEM-EDX results. Based on the results of CV analysis, the catalyst that has the largest ECSA (Electrochemical surface area) value is the catalyst milled using PCA and the milling time is three hours.

Preparation of U-Nb alloy from oxide precursors by direct oxide electrochemical reduction method

The aim of the present study was to prepare U-7 wt% Nb alloy by the direct oxide electrochemical reduction (DOER) method. The alloy was prepared from the mixed oxide precursors namely, UO2 and Nb2O5. When the precursors were sintered in a reducing atmosphere of Ar-8 vol% H2, Nb2O5 was converted into NbO2. Subsequently, the mixed oxide pellet (UO2-NbO2) was reduced by the lithium metal, electrochemically generated from a molten LiCl-1 wt% Li2O bath at 700 °C. The electro-lithiothermic reduction was performed by constant current electrolysis mode with a mixed oxide pellet as the cathode and platinum as the anode. The reduction pathways of the individual oxides and the mixture were established using cyclic voltammetry and potentiostatic electrolysis techniques. The reduced alloy was characterized by XRD and SEM-EDS. These results confirmed the formation of U-Nb alloy. The composition of the alloy was determined by EDS, EDXRF and chemical analysis.

Processing of aerogels and their applications toward CO2 adsorption and electrochemical reduction: a review.

Aerogels are a unique class of nanoporous ultralight materials exhibiting wide range of textural characteristic properties and tunable porosities. Due to their remarkable features such as low density, high surface area, low refractive index, small thermal conductivity, low dielectric constant and low sound velocity, they exhibit a wide range of applications in different areas such as electronics, thermal and acoustic insulation, chemistry, biomedicine and optics. The special advantages of these materials are that they can be produced in different forms such as monoliths/granular, bead/microspheres, thin films or sheets and as blankets. Aerogels are found to be potential materials for the removal of CO2 through adsorption or electrochemical reduction. There is a plethora of research on different kinds of aerogels used for CO2 adsorption process. Research has been going on toward the development of aerogel-based electrocatalyst, which can be used for valorization of CO2 through electrochemical reduction methods. Although most of the review papers have covered applications of aerogels in CO2 capture, very few discuss the processing of aerogels, more so on their applications in CO2 valorization. In this review, we have collated literature of different forms of aerogels currently available and the steps involved in their fabrication process. In addition, we have covered applications of aerogels in CO2 capture. Furthermore, we focussed on the basic principles involved in the development of an aerogel electrocatalyst as well as recent developments of aerogels in electrochemical CO2 reduction.

Black 3D-TiO2 Nanotube Arrays on Ti Meshes for Boosted Photoelectrochemical Water Splitting.

Black 3D-TiO2 nanotube arrays are successfully fabricated on the Ti meshes through a facile electrochemical reduction method. The optimized black 3D-TiO2 nanotubes arrays yield a maximal photocurrent density of 1.6 mA/cm2 at 0.22 V vs. Ag/AgCl with Faradic efficiency of 100%, which is about four times larger than that of the pristine 3D-TiO2 NTAs (0.4 mA/cm2). Such boosted PEC water splitting activity primarily originates from the introduction of the oxygen vacancies, which results in the bandgap shrinkage of the 3D-TiO2 NTAs, boosting the utilization efficiency of visible light including the incident, reflected and/or refracted visible light captured by the 3D configuration. Moreover, the oxygen vacancies (Ti3+) can work as electron donors, which leads to the enhanced electronic conductivity and upward shift of the Fermi energy level, and thereby facilitating the transfer and separation of the photogenerated charge carrier at the semiconductor-electrolyte interface. This work offers a new opportunity to promote the PEC water splitting activity of TiO2-based photoelectrodes.

Controllable synthesis and characterization of high purity calcium carbonate whisker-like fibers by electrochemical cathodic reduction method

Although the electrochemical method has been certificated as a promising way for the synthesis of calcium carbonate whiskers, researches on the controllability and efficiency are ignored. In this work, the electrochemical synthesis of calcium carbonate whiskers was studied to evaluate its controllability and efficiency. Micrograph and X-ray diffraction analysis results indicated calcium carbonate whiskers was successfully synthesized with a high production of 94.59% by using electrochemical method to stimulate cathodic reaction in calcium-containing solution. Length and aspect ratio of whisker can be controlled by regulating nucleation and growth conditions. The optimal conditions for whiskers synthesis were nucleating 5 min at 18 V and growing 55 min at 2 V in the solution containing 600 mg/L of calcium chloride, 300 mg/L of sodium bicarbonate, and 150 mg/L of magnesium chloride with a constant temperature of 70 °C. The calcium carbonate whisker has an 18.78 μm whisker length and 36.82 aspect ratio. The product morphology depended on the uniformity of carbonate and the presence of magnesium. The uniform distribution of the generated CO 3 2− was responsible for producing CaCO 3 whiskers. Besides, presence of magnesium can avoid of hydroxide overproduction and regulate supersaturation of CaCO 3 during synthesis to control the one-dimensional growth of whiskers. This work demonstrated the potential of controllable and efficient synthesis of calcium carbonate whiskers using electrochemical method. • Synthesize calcium carbonate whiskers with aspect ratio of 36.82 on stainless-steel cathode. • Whiskers length and aspect ratio were controlled through regulating nucleation voltage and reaction temperature. • Whiskers morphology depended on the uniformity of carbonate and the presence of magnesium. • Colloidal precipitate of Mg(OH) 2 promoted the one-dimensional growth of calcium carbonate crystals.

Photoelectrochemical CO2 Reduction Products Over Sandwiched Hybrid Ga2O3:ZnO/Indium/ZnO Nanorods

Recycled valuable energy production by the electrochemical CO2 reduction method has explosively researched using countless amounts of developed electrocatalysts. Herein, we have developed hybrid sandwiched Ga2O3:ZnO/indium/ZnO nanorods (GZO/In/ZnONR) and tested their photoelectrocatalytic CO2 reduction performances. Gas chromatography and nuclear magnetic spectroscopy were employed to examine gas and liquid CO2 reduction products, respectively. Major products were observed to be CO, H2, and formate whose Faradaic efficiencies were highly dependent on the relative amounts of overlayer GZO and In spacer, as well as applied potential and light irradiation. Overall, the present study provides a new strategy of controlling CO2 reduction products by developing a sandwiched hybrid catalyst system for energy and environment.

Electrochemical reductive cross-coupling of acyl chlorides and sulfinic acids towards the synthesis of thioesters

In this context, we used an electrochemical reduction method to obtain thiyl radicals from sulfinic acids. In a simple undivided cell, various acyl chlorides and sulfinic acids were compatible, generating 40 examples of the desired thioesters.

Introducing oxygen vacancies to NiFe LDH through electrochemical reduction to promote the oxygen evolution reaction.

The transition metal hydroxide NiFe LDH is a promising oxygen evolution reaction (OER) catalyst. Surface engineering, such as the introduction of oxygen vacancies into NiFe LDH, has been reported to further improve the OER performance; however, searching a facile approach remains an issue. In this work, we report a novel and efficient electrochemical reduction method for in situ introduction of oxygen vacancies into NiFe LDH laminates by applying a constant negative voltage. The results show that the reduced NiFe LDH (denoted as r-NiFe LDH) exhibits enhanced OER performance versus its counterpart NiFe due to the increase of oxygen vacancy density, the electrochemically active surface area, wetting ability, and the significant electron transfer rate. In 1 M KOH, the r-NiFe LDH shows a high current density of 110 mA cm-2 at 1.60 V (vs. RHE), which is 2.8 times the current density of NiFe LDH (40 mA cm-2), as well as the long-term stability of 100 h. This electroreduction method is also applicable to other LDH materials loaded by different current substrates or synthesized by various methods, demonstrating its universality for the enhancement of the OER activity of LDH electrocatalysts.

Rapidly reconstructing the active surface of cobalt-based perovskites for alkaline seawater splitting.

As a potential oxygen evolution reaction (OER) catalyst, Co-based perovskites have received intensive attention. However, Sr readily accumulates on their surface, and makes them inert toward the OER. Herein, we propose a simple but versatile electrochemical reduction method to reconstruct the active surface of Co-based perovskites within a few seconds. By this method, Sr rapidly precipitates from Co-based perovskites, accompanied by the introduction of Sr and oxygen vacancies. After reconstruction, the electrochemical active surface areas of Co-based perovskites greatly increase, and the OER overpotential of the optimized SrNb0.1Co0.7Fe0.2O3-δ (ER-SNCF-20s) reaches 278 mV at 10 mA cm-2. This can be explained by the decrease of overpotentials at the rate-determining step. Using ER-SNCF-20s, the splitting voltage of alkaline natural seawater can reach 1.56 V at 10 mA cm-2, and remains steady for 300 h. This effort offers a feasible method for reconstructing the active surface of Co-based perovskites.

STUDY OF THE EFFECT OF THE CHANGE IN THE APPLIED POTENTIAL DIFFERENCE ON THE PROPERTIES OF CdSe: Ni THIN FILMS

This work is devoted to the study of the efficiency of using the effect of nickel doping of thin films based on CdSe with the possibility of varying the structural and optical properties due to a change in the phase composition of the films. The method of electrochemical reduction of metal ions from aqueous solutions of electrolytes was chosen as a method for obtaining films. The variation of the applied potential difference was used to produce films with different characteristics. To characterize the properties and dynamics of their changes, methods of atomic force microscopy, energy dispersion analysis and X-ray diffraction were chosen. The strength mechanical properties of the films were studied using the indentation method. During experiments conducted dependencies of changes of structural, optical, strength characteristics of synthesized films depending on production conditions are obtained. Photocatalytic tests to determine the rate and efficiency of decomposition of the Rodamine B organic dye showed that films in the composition of which the NiSe phase prevails have the greatest potential for use as photocatalysts.

Palladium-Nickel Electrocatalysts on Nitrogen-Doped Reduced Graphene Oxide Nanosheets for Direct Hydrazine/Hydrogen Peroxide Fuel Cells

In the present work, nitrogen-doped reduced graphene oxide-supported (NrGO) bimetallic Pd–Ni nanoparticles (NPs), fabricated by means of the electrochemical reduction method, are investigated as an anode electrocatalyst in direct hydrazine–hydrogen peroxide fuel cells (DHzHPFCs). The surface and structural characterization of the synthesized catalyst affirm the uniform deposition of NPs on the distorted NrGO. The electrochemical studies indicate that the hydrazine oxidation current density on Pd–Ni/NrGO is 1.81 times higher than that of Pd/NrGO. The onset potential of hydrazine oxidation on the bimetallic catalyst is also slightly more negative, i.e., the catalyst activity and stability are improved by Ni incorporation into the Pd network. Moreover, the Pd–Ni/NrGO catalyst has a large electrochemical surface area, a low activation energy value and a low resistance of charge transfer. Finally, a systematic investigation of DHzHPFC with Pd–Ni/NrGO as an anode and Pt/C as a cathode is performed; the open circuit voltage of 1.80 V and a supreme power density of 216.71 mW cm−2 is obtained for the synthesized catalyst at 60 °C. These results show that the Pd–Ni/NrGO nanocatalyst has great potential to serve as an effective and stable catalyst with low Pd content for application in DHzHPFCs.

Silver/poly(vinyl alcohol)/graphene hydrogels for wound dressing applications: Understanding the mechanism of silver, antibacterial agent release

AbstractLong‐term wound healing and chronic wound care represent significant challenges for biomaterials science and engineering with many diverse requirements for the wound dressing properties, as well as antibacterial efficacy and antibacterial agent release to prevent and treat persistent infections. Silver nanoparticles, as a wide‐spectrum antibacterial agent that does not induce bacterial resistance, are very convenient for use as an active component in antibacterial hydrogel wound dressing materials with the controlled release ability. In this work, we aim to perform a comprehensive analysis of silver release from poly(vinyl alcohol)‐based hydrogels with electrochemically synthesized antibacterial silver nanoparticles (AgNPs), aimed for wound dressing applications. Different AgNPs concentrations were loaded in hydrogel matrices using the green electrochemical reduction method, and thus synthesized nanocomposite hydrogels were characterized by different techniques (scanning electron microscopy, Fourier‐transform infrared and Raman spectroscopy, and differential scanning calorimetry), in order to assess their physico‐chemical and thermal properties. Silver release was monitored for 28 days in physiologically‐relevant conditions (phosphate buffered medium, pH 7.4, 37°C). The obtained experimental data were evaluated against several theoretical release models (Korsmeyer‐Peppas, Higuchi, Makoid‐Banakar, Kopcha, and early‐time approximation), which confirmed the predominantly diffusion‐controlled mechanism of release. Finally, AgNP‐loaded hydrogels were assessed for antibacterial activity againstStaphylococcus aureusTL andEscherichia coliATCC25922 bacterial strains, to prove their strong potential for wound dressing applications.