Lower Charge Transfer Resistance Research Articles

Regulating Interphase Chemistry by Targeted Functionalization of Hard Carbon Anode in Ester-based Electrolytes for High-Performance Sodium-Ion Batteries.

Commercial hard carbon (HC) anode suffers from unexpected interphase chemistry rooted in the parasitic reactions between surface oxygen-functional groups and ester-based electrolytes. Herein, an innovative strategy is proposed to regulate interphase chemistry by tailoring targeted functional groups on the HC surface, where highly active undesirable oxygen-functional groups are skillfully converted into a Si-O-Si molecular layer favorable for anchoring anions. Then, an inorganic/organic hybrid solid electrolyte interphase with low interfacial charge transfer resistance and enhanced cycling durability is constructed successfully. Consequently, the modified HC anode delivers an excellent rate capability of 206.2 mAh g-1 at 0.5 A g-1 and a remarkable capacity retention of 92.5% after 1000 cycles at 1.0 A g-1. Moreover, the coin-type full-cell equipped with Na2Fe[Fe(CN)6] cathode exhibits an exceptional capacity retention ratio of 80.9% after 800 cycles at 1C. The present simple and effective interfacial modification strategy offers a promising and alternative avenue for promoting the development and practicability of HC anode in ester-based electrolytes for sodium-ion batteries.

Low Pt Loading on Wolframite-Type NiWO4 to Excel the Electrocatalytic Water Splitting and Ammonia Oxidation Reaction.

Hydrogen production via water-splitting or ammonia electrolysis using transition metal-based electrodes is one of the most cost-effective approaches. Herein, ca. 1-4% of Pt atoms are stuffed into a wolframite-type NiWO4 lattice to improve the electrocatalytic efficiency. The co-existence of atomically dilute quantities of Pt0 and PtIV atoms in the NiWO4 without altering the lattice structure is established via powder X-ray diffraction, inductively coupled plasma mass spectrometry (ICP-MS), core-level X-ray photoelectron spectroscopy, and other spectroscopic studies. While the undoped NiWO4 and a physical mixture of Pt0 (2 wt %) and NiWO4 exhibit poor oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and ammonia oxidation reaction (AOR) activities, 3-4% Pt-enriched NiWO4 depict improved electrocatalytic performances with at least 50 mV overpotential drop for both the OER and HER. The 3%Pt/NiWO4 electrode showcases a long-term (for 110 h) chronoamperometric/chronopotentiometric OER and HER performance, delivering high current at a low working potential. The bifunctional behavior of the material leads to the development of a water-splitting electrolyzer, 3%Pt/NiW/NF(-)/(+)3%Pt/NiW/NF, achieving >90% Faradaic efficiency for H2 production. The onset potential for the AOR is also cathodically shifted for 3%Pt/NiW and 4%Pt/NiW compared to the NiWO4 itself. Electrokinetic study through a rotating ring-disk electrode (RRDE) experiment and the Koutecký-Levich study provides an observed rate constant (kobs) of 1.68 × 10-3 cm s-1 of AOR with a 6e- count from the kinetic current region, highlighting [NO2]- as the major product. The electrolysis of 1 M NH3 using 4%Pt/NiW/NF as a working electrode produces predominantly [NO2]- (FE: 53%) and [NO3]- (FE: 30%). The improved electrocatalytic activity of 3-4% Pt-enriched NiWO4 can be due to the low Tafel slope and charge transfer resistance (Rct). Pt0 being electron-rich induces facile electronic conduction during electrocatalysis and enhances a better binding of the analytes such as H2O, [OH]-, and NH3. At the same time, the PtIV centers present adjacent to the NiII sites can polarize the electron density to stabilize NiIII species and enhance the possibility of OER and AOR. This study demonstrates the effect of hetero-metal doping to tune the electronic structure to improve the electrochemical activity. The low-Pt-doped NiWO4 material is presented here as a multimodal electrocatalyst that can efficiently electrolyze water or ammonia to produce hydrogen.

Unveiling the Redox Characteristics of Rutin Trihydrate-Canvas-Based Sensor for Hydrazine Sensing in Water Samples.

The inclusion of redox mediators into electrocatalytic systems facilitates rapid electron shuttling kinetics and boosts the overall catalytic performance of the electrode. This approach overcomes the sluggish reaction dynamics associated with direct electron transfer, which may be impeded by restricted analyte access to the electrode's active sites. In contrast to conventional synthetic redox mediators, naturally sourced phytomolecule rutin trihydrate (RT), extracted from apple juice, offers potential ecological advantages. This bands with green chemistry principles and sustainability in electroanalytical approaches. The current work presents an eco-friendly and direct electrochemical approach to fabricate a redox-active RT-immobilized MWCNT-infused PEDOT hybrid material-modified glassy carbon electrode (GCE/MWCNT + PEDOT@RT). The developed electrode showcased a sharp and stable redox signal at E0 = 0.63 V vs Ag/AgCl with no surface-fouling characteristics. The efficacious functionalization of RT onto MWCNT + PEDOT was corroborated by a remarkable increase in the surface characteristics, enhanced electrochemical current responses, and low charge transfer resistance. The GCE/MWCNT + PEDOT@RT exhibited highly selective and sensitive sensing responses toward the toxic and potentially carcinogenic hydrazine (HZ) via cyclic voltammetry and differential pulse voltammetry techniques, yielding a low detection limit (DL) of 1.02 μM and a sensitivity of 0.032 μA μM-1 in a linear dynamic range between 0 and 1350 μM. In addition, the method was highly efficient for HZ detection in real samples of tanker, tap, and wastewater samples, producing a good recovery of ∼98%.

Electrochemical Performance of Pre-Modified Birch Biochar Monolith Supercapacitors by Ferric Chloride and Ferric Citrate

This study investigated the electrochemical properties of supercapacitors by pre-modifying thick birch biochar monoliths with FeCl3 or C6H5FeO7 solutions prior to wood pyrolysis. The pre-modification introduced iron species to the surface, promoting the specific surface area, charge-stored species, and surface functionalities, which enhanced the gravimetric capacitance. X-ray diffraction confirmed the successful loading of Fe3O4 and Fe. SEM implied the wider distribution of iron-rich particulates and porous carbon via self-pyrolysis on the biochar surface modified with 1.0 M C6H5FeO7. Contact angle measurements demonstrated the enhanced wettability of the biochar surfaces following pre-modification, with the C6H5FeO7-modified samples exhibiting superior wettability compared to the other groups. The gravimetric capacitance of the supercapacitor was dramatically promoted and reached 210 F/g and 219 F/g, respectively, when modified with 1.0M C6H5FeO7 and 1.0 M FeCl3 at a 5 mA/g current density. Compared to the birch biochar modified with 1.0 M FeCl3, the 1.0 M C6H5FeO7 had a higher current response peak and capacitive behavior in the CV analysis, demonstrated better ion diffusion capacity, and had lower charge-transfer resistance in the EIS results. But, a slight irreversible process on the electrode of the 1.0 M C6H5FeO7 group led to a lower level of the supercapacitor capacitance retention. The results using ferric solution pre-impregnation show how iron species doping can improve capacitance behavior, providing a feasible scheme for the modification of thick biochar monolith.

Controllable Synthesis and “Fast‐charging” Mechanism of Hollow‐Micropencil Co3V2O8 from Perspective of Ion Diffusion in Crystal Structure

AbstractCo3V2O8 as a bimetallic oxide with “fast‐charging” capacity presents some potential advantages, comprising decent theoretical specific capacity, favorable crystal structure, and intrinsic safety. Presently, although extensive research of Co3V2O8 as an anode material are reported, the formed Co° from Co3V2O8 after the initial discharging is not oxidized to CoO during the charging process, and the ion diffusion mechanism are not well clarified. The lithium‐storage process of Co3V2O8 and the diffusion mechanism of lithium ion in Co3V2O8 are studied in detail in this work. A hollow‐micropencil Co3V2O8 prepared through the hydrothermal method without using surfactants or templates demonstrates a high “fast‐charging” capability even at the current densities as high as 1.0–2.0 A g−1. The electrochemical kinetic results illustrate that the hollow‐micropencil Co3V2O8 presents low charge transfer resistance. The distinctive lithium ion storage sites as well as diffusion paths are predicted. The in situ X‐ray diffraction analysis is adopted to confirm that the formed Co° after the initial discharging is not oxidized to CoO during the delithiation process. The work not only helps to understand the lithium insertion mechanisms of Co3V2O8 but also offers new means to develop “fast‐charging” anode material for lithium‐ion batteries with remarkable electrochemical performance.

Construction of Cu2MoS4/ZnO Heterostructures and Mechanism of Photocatalytic Hydrogen Production.

Constructing wide and narrow band gap heterogeneous semiconductors is a method to improve the activity of photocatalysts. In this paper, CMS/ZnO heterojunctions were prepared by solvothermal loading of ZnO particles on the surface of Cu2MoS4 nanosheets. The photocatalytic H2 precipitation rate is about 545 μmol·g-1·h-1, which is 6.8 times that of Cu2MoS4 and 3 times that of ZnO without any cocatalyst. After etching modification of CMS, the photocatalytic hydrogen production efficiency of the ECMS/ZnO heterojunction is further improved. Its hydrogen production efficiency reaches about 1115 μmol·g-1·h-1, which is 9 times that of ECMS and 6 times that of ZnO. The reasons are mainly attributed to the following two factors: (1) the formation of the ECMS/ZnO type-II-type heterojunction facilitates the effective separation of photogenerated electrons and holes; (2) the band structure of Cu2MoS4 was optimized by etching modification, which made the ECMS/ZnO heterojunction have lower interfacial charge transfer resistance and improved the photocatalytic hydrogen production activity of the heterojunction.

Electrical activation of periodate by nano-zero-valent cobalt/nitrogen-doped carbon for sulfisoxazole degradation: Insights into rapid electron transfer mechanisms.

Periodate (PI) activation via three-dimensional electrochemical (E) is a promising approach for degrading sulfisoxazole (SIZ), while the scarcity of active sites significantly limits the efficient electron-transfer rate. Herein, we synthesized multiple strongly active zero-valent cobalt (Co0) nanoparticles encapsulated in nitrogen-doped carbon (NC) shells through Co-potassium chloride (KCl) doping pyrolysis of Zeolitic Imidazolate Framework-8 (ZIF-8) to induce the rapid electron transfer pathways (ETP). Specifically, molten KCl doping provides confined structures for Co0 with a diameter of 12.57nm embedded in the NC shell, thereby expanding the active space of Co0/NC. The generated Co0/NC exhibited an enormous electrochemically active surface area (ECSA, 736.92cm2/mg), low charge transfer resistance (Rct, 38.50 Ω), and strong adsorption energy (-6.003eV), which together promote robust electron transfer kinetics. Capitalizing on these properties, the E-Co0/NC-PI system achieved 100% SIZ removal at a degradation rate of 1.587min-1 under near-neutral (pH 5.00-9.00) conditions, with ultra-low energy consumption (0.011kWhm-3, $0.125/L). This study highlights a Co0/NC-induced rapid ETP for SIZ removal, offering insights into enhanced electrical activation of PI for wastewater treatment.

CO driven tunable syngas synthesis via CO2 photoreduction using a novel NiCo bimetallic metal-organic frameworks.

Syngas has important industrial applications, and converting CO2 to CO is critical for syngas production. Metal-organic frameworks (MOFs) have demonstrated significant potential in photocatalytic syngas conversion, although the impact of catalytic reactions on tunable H2/CO ratios remains unclear. Herein, we present a novel bimetallic NiCo-MOF catalyst, Ni0.4Co0.6, exhibiting high catalytic activity in syngas conversion due to the CO product self-driven effect. Our investigation, integrating experimental data with density functional theory (DFT) analysis, uncovers a high photocurrent response and a low charge-transfer resistance. Furthermore, the introduction of cobalt into Ni-MOF caused an upshift of the d-band center, which facilitated the conversion efficiency of *COOH intermediates, which has been identified as the rate-determining step in CO2 conversion, resulting in increased CO yield. Additionally, the concentration of undesorbed CO rises, while CO co-adsorption diminishes the catalyst's binding energy for *H, thereby enhancing H2 generation. These combined effects contribute to a self-driven enhancement in the catalytic production of syngas. By adjusting the Ni/Co ratio, a tunable H2/CO ratio (0.21-0.85) was achieved, with Ni0.4Co0.6 exhibiting optimal catalytic performance, yielding 17.6mmol·g-1·h-1 gas products. This study provides a novel insight into the correlation between reaction products and catalyst design, offering a perspective on perspective on modulating syngas composition.

Additively Manufactured Collector-Detector Device for Explosive Analysis Using Recycled PLA Filament Loaded with Carbon Black and Graphite

We report the electrochemical potential of conductive filaments produced with recycled polylactic acid (rPLA) alongside a mixture of graphite (Gpt) and/or carbon black (CB) and castor oil to create an electrode ready-to-use. Additively-manufactured electrodes (AMEs) were compared with commercial-conductive filament composed of PLA and CB. The Gpt-CB-rPLA and CB-rPLA sensors showed lower charge-transfer resistance (Rct) and a greater heterogenous rate constant, k0 , (Rct = 1040 ± 50 Ω and 1810 ± 30 Ω and k0 = 6.91 (± 0.58) ×10-3 and 5.31 (± 0.40) × 10-3 cm s-1, respectively) compared to the sensor from the commercial filament (Rct = 9620 ± 280 Ω and k0 = 3.62 (± 0.38) ×10-3 cm s-1). The electrochemical response of [Fe(CN6)]3-/4- displayed a peak-to-peak separation of 180 ± 8 mV (Gpt-CB-rPLA) and 240 ± 6 mV (CB-rPLA) compared to commercial AME (740 ± 10 mV), without any surface treatment. The filaments were used to create a 2,4,6-trinitrotoluene (TNT) detection platform with linear range of 5-20 and 5-100 µmol L-1 for Gpt-CB-rPLA and CB-rPLA, respectively. The collector-detector device was applied for the analysis of a blast simulation. Finally, it is worth noting that the results obtained are without electrode treatment/activation, indicating that the rough surface of the additively manufactured electrode is an additional feature of the device for collecting explosive residues, simply by rubbing the additively manufactured platform on different surfaces in crime scenarios.

PRODUCTION OF HIGH-PERFORMANCE SUPERCAPACITOR ELECTRODES BASED ON GRAPHENE-LIKE CARBON OBTAINED FROM TEA WASTE

This article presents the results of a study on the production of active material for supercapacitor electrodes from graphene-like carbon obtained from tea waste, carbonization at a temperature of 550°C, followed by thermochemical activation using potassium hydroxide in a ratio of 1:4 at a temperature of 850°C in a quartz tube furnace. The structure and morphology of the resulting porous graphene-like carbon based on tea waste were investigated using scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), X-ray diffraction, and Raman spectroscopy. The surface area of activated porous graphene-like carbon from tea waste was 2407 m2/g. Electrochemical characterization of the assembled supercapacitor using GLC-TW was performed on an Elins P-40X electrochemical workstation and showed high specific capacitance values of 182 F/g, as well as a Coulombic efficiency of 96% at a current density of 1 A/g and the material also demonstrated a low charge transfer resistance of about 1.5 Ohms. These results highlight the effectiveness of using graphene-like carbon derived from tea waste, demonstrating its potential as a promising material for supercapacitors.

Carbon Felts Uniformly Modified with Bismuth Nanoparticles for Efficient Vanadium Redox Flow Batteries.

The integration of intermittent renewable energy sources into the energy supply has driven the need for large-scale energy storage technologies. Vanadium redox flow batteries (VRFBs) are considered promising due to their long lifespan, high safety, and flexible design. However, the graphite felt (GF) electrode, a critical component of VRFBs, faces challenges due to the scarcity of active sites, leading to low electrochemical activity. Herein, we developed a bismuth nanoparticle uniformly modified graphite felt (Bi-GF) electrode using a bismuth oxide-mediated hydrothermal pyrolysis method. The Bi-GF electrode demonstrated significantly improved electrochemical performance, with higher peak current densities and lower charge transfer resistance than those of the pristine GF. VRFBs utilizing Bi-GF electrodes achieved a charge-discharge capacity exceeding 700 mAh at 200 mA/cm2, with a voltage efficiency above 84%, an energy efficiency of 83.05%, and an electrolyte utilization rate exceeding 70%. This work provides new insights into the design and development of efficient electrodes, which is of great significance for improving the efficiency and reducing the cost of VRFBs.

Synthesis of nitrogen-doped carbon dot/tin disulfide nanosheet composite electro-catalysts for dye-sensitized solar cells

Nitrogen-doped carbon dots (N-CDs) and vertically-grown tin disulfide (SnS2) nanosheets are synthesized via hydrothermal method and chemical vapor deposition technique, respectively. The SnS2nanosheets are directly fabricated on flexible carbon cloth (CC), and then their basal planes are decorated with N-CDs. The as-prepared composite electrodes are used as the counter electrode for the application in dye-sensitized solar cells (DSSCs). The characterizations of N-CDs and SnS2nanosheets are studied by high resolution transmission electron microscopy, scanning electron microscopic, energy dispersive x-ray spectrometer, Raman spectrometer and x-ray photoelectron spectroscopy etc. Moreover, the cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and photocurrent-density voltage are utilized to understand the electro-catalytic performance of N-CDs/SnS2/CC composite counter electrode. The N-CDs/SnS2/CC composite electrode shows higher cathodic reduction current density and lower charge transfer resistance in CV and EIS measurements, respectively, as compared to those of the electrodes with N-CDs or SnS2alone. Meanwhile, the DSSC using N-CDs/SnS2/CC exhibits cell efficiency (η) of 7.68%, which is higher than those of cells having SnS2/CC (η= 7.54%) and N-CDs/CC (η= 5.66%) counter electrodes, respectively; it also reaches 94% cell efficiency of the cell using Pt/CC counter electrode (η= 8.15%). The design concept of the modification of the basal planes by defect-rich carbon dots (i.e. N-CDs) and highly-exposed edge sites (i.e. vertically-grown SnS2nanosheets) makes promising route to enhance the performance of two-dimensional electro-catalysts.

Impact of the Metal-Organic Frameworks Polymorphism on the Electrocatalytic Properties of CeO2 toward Oxygen Evolution.

Hydrogen (H2) is a viable alternative as a sustainable energy source, however, new highly efficient electrocatalysts for water splitting are still a research challenge. In this context, metal-organic frameworks (MOFs)-derived nanomaterials are prominent high-performance electrocatalysts for hydrogen production, especially in the oxygen evolution reaction (OER). Here, a new synthesis of two cerium oxide (CeO2) electrocatalysts using Ce-succinates MOFs as templates is proposed. The cerium succinates polymorphs ([Ce2(Succ)3(H2O)2], Succ = succinate ligand) were obtained via hydrothermal reaction and room temperature crystallization, adopting monoclinic (C/2c) and triclinic (P1̅) crystalline structures, respectively, confirmed by X-ray diffraction (XRD). MOFs-Ce were also characterized by infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). CeO2 electrocatalysts were obtained via MOFs-Ce calcination at 350 °C in air, and characterized by XRD with Rietveld refinement, HRTEM, SEM, FT-IR, and Raman spectroscopy, UV-vis spectroscopy, X-ray photoelectron spectroscopy. Electrocatalytic performances were investigated in KOH 1.0 M solution, and overpotentials were η = 326 mV (for CeO2 (H) from monoclinic MOF-Ce) and η = 319 mV (for CeO2 (RT) from the triclinic MOF-Ce) for a current density of 10 mAcm-2. The Tafel slope values show the adsorption of intermediate oxygenated species as the rate-determining step. The high values of double-layer capacitance, the presence of oxygen vacancies, and low charge transfer resistance agree with the high performance in OER. Additionally, the materials were stable for up to 24 h, according to chronopotentiometry results.

VN Quantum Dots Anchored onto Carbon Nanofibers as a Superior Anode for Sodium Ion Storage.

Vanadium-based compounds exhibit a high theoretical capacity to be used as anode materials in sodium-ion batteries, but the volume change in the active ions during the process of release leads to structural instability during the cycle. The structure of carbon nanofibers is stable, while it is difficult to deform. At the same time, the huge specific surface area energy of quantum dot materials can speed up the electrochemical reaction rate. Here, we coupled quantum-grade VN nanodots with carbon nanofibers. The strong coupling of VN quantum dots and carbon nanofibers makes the material have a network structure of interwoven nanofibers. Secondly, the carbon skeleton provides a three-dimensional channel for the rapid migration of sodium ions, and the material has low charge transfer resistance, which promotes the diffusion, intercalation and release of sodium ions, and significantly improves the electrochemical activity of sodium storage. When the material is used as the anode material in sodium ion batteries, the specific capacity is stable at 230.3 mAh g-1 after 500 cycles at 0.5 A g-1, and the specific capacity is still maintained at 154.7 mAh g-1 after 1000 cycles at 2 A g-1.

Toward Efficient Hydrogen Generation Using Nickel-Molybdenum Catalyst and Its Environmental Sustainability.

In this study, a catalyst with Ni-Mo combination was synthesized using the electric heating/reductive tempering method. Nickel (II) nitrate hexahydrate and ammonium molybdate were combined in a ratio of 1.1 in this approach. The mixture was milled into a fine powder. It was heated to 950°C to 1000°C in a seething hood. The disappearance of green shading and emission of brownish-yellow fumes indicated that the reaction was completed. XRD has been used to determine the crystallinity of the combined Ni-Mo amalgam, SEM was used to investigate the surface morphology of the orchestrated Ni-Mo compound, and inductively coupled plasma examinations were carried out to evaluate elemental percentage (%) of the integrated sample of Ni-Mo combination. In addition, an electrical impedance analysis of as-synthesized Ni-Mo alloy was conducted to estimate hydrogen production in an electrochemical reaction. The electrical impedance results indicate that the synthesized Ni-Mo catalyst exhibited an efficient charge-transfer kinetics with a low charge-transfer resistance (5.35 Ω). The onset potential value achieved was 18 mV with overpotential of -100 mV in IM KOH, possessing a turnover frequency of 0.91H2 s-1. These findings underscore Ni-Mo catalyst as a promising catalyst for hydrogen generation studies. The results of this study are anticipated to be of potential significant importance in providing a cost-effective approach towards the synthesis of Ni-bimetallic catalyst, which in the future can serve as a promising candidate for applications involving sustainable hydrogen generation. Additionally, the proposed method's study of its greenness using the Analytical Greenness Calculator (AGREE) can help advance the usage of renewable and environmentally friendly energy sources.

A dual-activation strategy for enhancing the energy storage performance of MoSe2/AFCNTs in symmetric supercapacitors

The MoSe2/AFCNTs composite obtained via one-step hydrothermal process demonstrates significant promise as supercapacitor electrode material. In this process, MoSe2 nanoflowers are decorated on the surface of activated functional carbon nanotubes (AFCNTs) which are functionalized through a dual-activation method involving acid and alkaline treatment. The resulting composite benefits from plentiful active sites and low charge-transfer resistance, which together contribute to its excellent energy storage and capacitive performance. The electrochemical performance of MoSe2/AFCNTs in a three-electrode system is impressive, with a specific capacitance of 335 F g−1 at a current density of 1 A g−1. This value is much higher than that of either individual MoSe2 or carbon nanotubes, highlighting the synergistic effect between the two components. When used in a symmetric supercapacitor device, MoSe2/AFCNTs delivers a maximum power density of 1.25 kW kg−1 and an energy density of 1.39 Wh kg−1. Additionally, this device can supply power for electric watch, demonstrating that the MoSe2/AFCNTs composite is a competitive supercapacitor electrode material in practical application.

Rare earth doped CeO2 uniformly enwraps graphite felt as high current density electrode for all vanadium redox flow battery

Although the introduction of metal oxides can solve the problem of poor electrochemical activity of graphite felt electrode, their low conductivity, poor dispersibility, and difficulty in nanocrystallization restrict their application development. Herein, a uniform distributed Gd or Sm doped CeO2 nanoparticle decorated graphite felt electrode is successfully prepared by hydrothermal method. The incorporation of Gd3+ or Sm3+ into the lattice of CeO2 results in the formation of numerous oxygen vacancies, acting not only as reaction sites for redox reactions but also enhancing the charge transfer rate. Compared to CeO2/GF, Ce0.8Gd0.2O2/GF and Ce0.8Sm0.2O2/GF exhibits superior electrochemical activity and lower charge transfer resistance. Correspondingly, the energy efficiency of Ce0.8Gd0.2O2/GF and Ce0.8Sm0.2O2/GF increases 4.5 % and 7.8 % at 160 mA cm−2, respectively. The maximum operating current density of Ce0.8Sm0.2O2/GF is 200 mA cm−2, while Ce0.8Gd0.2O2/GF is 160 mA cm−2. Ce0.8Sm0.2O2/GF achieves an energy efficiency of 69.3 % using a flow-by flow field at 200 mA cm−2. The optimal doping concentration for Sm is 20 %. The Ce0.8Sm0.2O2/GF stably operate for 500 cycles at 100 mA cm−2 and the Ce0.8Sm0.2O2 nanoparticles adhere firmly to the GF without observed detachment. These results demonstrate that Ce0.8Sm0.2O2/GF with high activity and stability is a promising electrode for VRFB.

Enhanced electrocatalytic performance and exceptional durability facilitate the effective degradation of m-dinitrobenzene wastewaters utilizing a novel SS/PbO2-Y2O3-SiC electrode

The intrinsic toxicity of m-dinitrobenzene (m-DNB) to human health and the environment has made dealing with m-DNB pollution a major concern. Herein, a novel hydrophobic anodic electrode SS/PbO2-Y2O3-SiC doped with Y and SiC was constructed via a simple electrodeposition strategy for efficient degradation of m-DNB. With a dense-uniform structure and hydrophobic surface, such SS/PbO2-Y2O3-SiC electrode exhibits obviously lower activation energy (8.17kJmol−1) and charge transfer resistance (1.15 Ω cm2), higher electrochemical active area (46.14 cm2) and stability (359 d), in comparison to SS/PbO2. The m-DNB removal efficiency of the as-prepared SS/PbO2-Y2O3-SiC anode was significantly increased to 96.4% in 180minutes, and the degradation reaction-order was determined to be 0.9559, which was in accordance with the quasi-first-order reaction kinetics. These are the possible degradation pathways of m-DNB under the action of both cathodic and anodic reactions, according to the GC-MS results. The -NO2 group of m-DNB was first reduced to the -NH2 group at the cathode surface, and then the m-phenylenediamine generated at the cathode was sequentially oxidised by the hydroxyl radicals generated from the anodic electrochemical process, resulting in the generation of H2O and CO2 at the anode surface. Additionally, the Assessment Software Tool (TEST) shows that the SS/PbO2-Y2O3-SiC anode can effectively reduce the risk and harm of m-DNB to the overall environment. This study offers novel perspectives on the development of a highly efficient PbO2 electrode for the degradation of m-DNB pollutants.

One-pot synthesis of 2D-Ni-MOF from waste PET plastic in aqueous medium for selective electrooxidation of glycerol, ethanol, and methanol

This study investigates the electrochemical performance and selectivity of a nickel-based metal-organic framework (Ni-MOF) catalyst synthesized from waste PET plastic using a one-pot approach in aqueous media. The Ni-MOF electrode was evaluated for glycerol electrooxidation reaction (GEOR), ethanol electrooxidation reaction (EEOR), and methanol electrooxidation reaction (MEOR). Linear sweep voltammetry (LSV) revealed current densities of 30mA/cm² at 0.5639V for GEOR, 50.07mA/cm² at 0.35V for EEOR, and 45.73mA/cm² at 0.39V for MEOR, indicating superior catalytic activity. Nyquist plots showed lower charge transfer resistance (Rct) values of 11.0 Ω for GEOR, 2.79 Ω for EEOR, and 2.69 Ω for MEOR, confirming efficient electron transfer. Bode impedance plots demonstrated lower impedance for alcohol electrooxidation compared to oxygen evolution reaction (OER). Chronoamperometry (CA) tests indicated excellent stability with 75.72% glycerol conversion for GEOR and selectivities of 94% for glyceric acid, 65.59% for acetic acid in EEOR, and 70.54% for formic acid in MEOR. These results highlight the potential of Ni-MOF derived from recycled PET plastic for sustainable and efficient electrooxidation of C1-C3 alcohols.

CdS-Titania nanocomposite: An improved visible active photocatalyst for dye degradation

Abstract Photocatalysis is emerged as a feasible solution for addressing the issues related to green energy production and sustainable environment. Among various reported photocatalysts, Titania is one of the widely used one due to its high stability, and low cost. However, its wide band gap and poor charge separation limits its photocatalytic performance in the UV region only. Coupling of Titania with suitable visible active semiconductor is a proven strategy to improve the performance. In this context, CdS-Titania (Anatase) nanocomposite has been synthesized via facile hydrothermal route and its impact on photon absorption and carrier separation efficiency were studied. The synthesized samples were characterized through various structural, optical and electrochemical analysis. X-ray diffraction pattern confirms the formation of CdS-Titania (Anatase) composite and its physicochemical properties. FE-SEM confirms the disintegration of CdS microspheres into smaller agglomerated particulates. The absorption spectroscopy confirms that induction of CdS improves the visible light absorption capacity. The composite consisting CdS-Titania (Anatase) (CdSA) shows the maximum red shift in the visible range. The low charge transfer resistance of composite observed in EIS analyses further confirms the proper separation of charge carriers at junction. The photocatalytic degradation performance under visible light irradiation was performed and found that the nanocomposite performs better than the pristine Anatase and CdS. CdSA has been found to have superior photocatalytic ability. It shows 43 times and 1.52 times better performance than pristine Titania and CdS respectively. This can be attributed to the enhanced visible photon absorption achieved through the successful formation of heterojunction. This opens up a new area of research for improving the performance of pristine Titania.