Reactive Surface Area Research Articles

Promoting bioelectrochemical performance of microbial fuel cells by using the polyhedral single atom catalyst Cu doping on g-C3N4 and NiFeCo-layered double hydroxide (SAC Cu-g-C3N4@NiFeCo-LDH)

Single atom catalyst Cu doping on g-C3N4 and NiFeCo-layered double hydroxide (SAC Cu-g-C3N4@NiFeCo-LDH) was prepared by hydrothermal method, consisting of Cu-doped g-C3N4 polyhedral monoatom combined with NiFeCo-LDH, as a cathode catalyst for microbial fuel cell (MFC). A narrow diamond-shaped blocks with irregular edges was observed in SAC Cu-g-C3N4@NiFeCo-LDH, contributing to provide abundant active sites and surface area for reaction. The maximum power density of 242.521 mW/m2 and output voltage of 0.843 V were obtained by SAC Cu-g-C3N4@NiFeCo-LDH MFC. Moreover, the output voltage of SAC Cu-g-C3N4@NiFeCo-LDH MFC could be stabilized at around 0.518 V with minimal variation within 4 d. The above results illustrated that SAC Cu-g-C3N4@NiFeCo-LDH possessed the superior ability to enhance the bioelectrochemical performance of MFCs. This study would provide a theoretical basis for the novel catalyst on MFC reactors.

Nanomolar level detection of phosphodiesterase 5 inhibitor drug tadalafil based on halide perovskite@HNTs nanocomposite electrode

As halide perovskites have taken a central role in the evolution of semiconductor materials, they are setting new standards for performance and revolutionizing the energy sectors. Unfortunately, little light is shed on the material's electrochemical sensing capabilities. This work reports the synthesis and characterization of a novel double halide perovskite Cs2CaSnCl6 (HDP) integrated with halloysite nanotubes (HNTs) for the electrochemical detection of Tadalafil (TAD). HDP@HNTs nanocomposite is synthesized using a simple solvothermal method and is characterized using various techniques like SEM, TEM, UV-visible, FT-IR, TGA/DTA, XRD and BET analysis. The results obtained from these characterizations confirmed the successful formation of the nanocomposite, revealed the material's endurance to high temperatures and the availability of a large surface area for reaction. Electrochemical characterization techniques like cyclic voltammetry (CV) and linear sweep voltammetry (LSV) demonstrated a linear correlation with the concentrations of TAD. Computational analysis of the TAD structure optimization, molecular electrostatic potential (MEP) of TAD and calculations regarding the HOMO-LUMO molecular orbitals are all carried out using the DFT/B3LYP method. The HDP@HNTs sensor is capable of achieving the lowest detection limit of 1.68 nM and the limit of quantification of 5.09 nM. The material showcased a remarkable sensitivity of 0.0104 µA nM-1 cm-2 from all the electrochemical parameters. Its reliability and stable performance even in the presence of real samples makes it a promising material for sensing applications. Thus, the reported framework contributes to the advancement in the development of sensors and enhanced healthcare outcomes.

Evaluation of CO2 Leakage Potential through Fault Instability in CO2 Geological Sequestration by Coupled THMC Modelling

A faulted saline aquifer system was simulated in a coupled thermal-hydraulic-mechanical-chemical (THMC) framework to examine the potential breaching of the caprock seal from long-term CO2 sequestration. The pH of the brines steadily dropped from 7.5 to 4.7 due to the continuous injection of scCO2 (supercritical CO2), which was caused by the rapid dissolution of calcite in the reservoir and associated fault zones, alongside alterations in the concentrations of primary and secondary minerals within the formation. The increase in pore pressure with the continuous injection of scCO2 triggered fault reactivation at 6y with the resultant leakage of CO2 along the fault. This builds CO2 saturation inside the fault at 7y to six-fold higher than pre-slip. Continuing shear reactivation and creation of reactive surface area following the initial CO2 leakage accelerates dissolution/precipitation reactions, in turn further increasing porosity and permeability of the reservoir and fault. In particular, the permeability and porosity in the fault zone were increased by only 2% and 6%, respectively – staunched by competitive feedbacks in dissolution countered by precipitation that are individually much larger. Comparison of mineral concentrations adjacent to the fault before-and-after instability revealed that the development of shear failure also promotes the transport of reactivated minerals into the fault zone. Among them, feldspar changes most significantly in later stages, dominated by dissolution with the volume fraction decreasing by 80% and increasing the aqueous concentration of K+ by approximately an order of magnitude. However, secondary minerals counter this dissolution through precipitation with the volume fraction of kaolinite increasing by an order of magnitude compared with the original fraction. Finally, the evolution of the fault sealing coefficient (FS) demonstrates that the porosity and permeability exert a pivotal influence in controlling the self-sealing behavior in the basal of the fault, while the upper fault layer exhibits self-enhancing response. A notable observation is that changes in mineral ion concentrations in fault zones could be applied as a significant diagnostic signal to monitor fault stability and the potential for progress of self-sealing behavior.

Electrospun polyvinyl alcohol/chitosan nanofibers modified with carbon nanotubes and sliver particles for electrochemical sensor application

Polyvinyl alcohol (PVA)/chitosan (CS) nanofibers modified with carbon nanotubes (CNT) and silver (Ag) particles are electrospun onto a graphite plate (GP) substrate to form the PVA-CS-CNT-Ag/GP electrode for electrochemical sensor application. Microstructure characterization demonstrates that PVA-CS nanofibers exhibit a loose and porous network structure, significantly improving the effective reaction surface area. Electrochemical measurements show the PVA-CS-CNT-Ag/GP electrode exhibits the limit of detection of 23.2 μM, the linear range of 65–176,460 μM and the sensitivity of 3.3945 μA cm−2 mM−1. Anti-interference test results show that the sensor has high selectivity towards H2O2. Stability test results indicate that the sensor exhibits good stability, as evidenced by the response current of 83.94 % after a period of 30 days. Simulation calculations indicate that PVA-CS-CNT-Ag exhibits lower interfacial energy (−2.3293 eV) compared to PVA-CS-CNT (−0.3674 eV) and PVA-CS-Ag (−0.7646 eV), smaller band gap (0.318 eV) compared to PVA-CS (3.640 eV), higher density of states at Fermi level (14.7332 electrons/eV) than others. Experimental measurements and simulation calculations indicate that PVA-CS-CNT-Ag electrospun nanofibers exhibit promising potential as an electroactive material for the electrochemical detection of H2O2.

Catalytic gasification of a single coal char particle: An experimental and simulation study

The catalytic coal gasification technology has been widely researched and developed under the background of “Carbon peaking and carbon neutrality goals”. Currently, most of catalytic gasification experiments on coal char particles are analyzed by thermogravimetric analyzer (TGA). However, the gasification agent will be subject to diffusion resistance during the reaction because of the sample stacking, making the inherent reaction kinetics unclear. In this study, we investigated the catalytic gasification behavior of single-particle coal char using high temperature stage microscope (HTSM). With the diffusion resistance ruled out, the reaction conditions when using a HTSM are more similar to those inside a real industrial gasifier. Numerical models of the gasification reaction of single-particle coal char were further developed using the kinetic parameters obtained under HTSM. Three models were investigated, including regular spherical structured, irregular spherical structured and porous spherical structured models, representing different morphologies of coal char particles in the gasifier. The gasification characteristics of coal char particles under different K2CO3 catalyst loadings and gasification temperatures were also studied. Compared with the activation energies data of coal char particles without catalyst, the activation energies of coal char particles loaded with 2.2 %, 4.4 %, 6.6 %, and 10.0 % catalysts were reduced by 110 kJ/mol, 116 kJ/mol, 121 kJ/mol, and 126 kJ/mol, respectively. The reaction surface area affects the temperature distribution. The temperature near the irregular spherical particle is about 20 K higher than the temperature near the regular spherical particle.

Zirconium hydroxide-activated carbon hybrid material for chemical warfare agents detoxification: Implication of water and temperature

In light of the recent threat from chemical warfare agents (CWAs), the scientific community has focused extensively on developing effective and safe decontamination methodology for CWAs based on environmentally benign technology and the avoidance of corrosive and toxic chemicals. Herein, we report the decomposition of CWAs sarin and sulphur mustard on the hybrid material Zirconium hydroxide-granular activated carbon i.e. Zr(OH)4@GAC which is synthesized by utilizing the reactive zirconium hydroxide and high surface area carbon. In-situ zirconium hydroxide was generated in the pores of GAC by varying the precursor concentration i.e. zirconium oxychloride followed by hydrolysis. The morphology, structural, and textural properties of the reactive hybrid material Zr(OH)4@GAC were examined using several analytical techniques including powder x-ray diffraction, TGA, FT-IR, BET, SEM, EDX, and TEM. Furthermore, the degradation capability of Zr(OH)4@GAC was evaluated in the hydrolytic abatement of CWAs sarin and sulphur mustard. Under pristine laboratory conditions, the effectiveness of reactive hybrid material Zr(OH)4@GAC has been attributed due to a combination of defects and diverse surface hydroxyl species of Zr(OH)4, as well as a high surface area carbon matrix. The impact of water content and temperature on CWAs degradation was also investigated by altering the water percentage from 2 to 8 % and the temperature 25 °C to 45 °C. The GC–MS/GC technique was used to observe the kinetics of in-situ degradation of CWAs over Zr(OH)4@GAC The results indicated that the degradation process follows a first-order reaction kinetics. It is observed that higher water content along with elevated temperature enhance CWA decomposition on Zr(OH)4@GAC; conversely, at lower temperature, it slowed down the degradation of CWAs. This significant enhancement in the decontamination capability of hybrid materials Zr(OH)4@GAC towards CWAs was attributed to the synergistic effects of GAC (adsorption capacity) coupled with the reactive functional group of Zr(OH)4.This strategy will pave the way for the development of self-detoxifying adsorbent material for environmental and defence purposes.

Impact of ultrasonic treatment duration on the microstructure and electrochemical performance of NiZnCo2O4 electrode materials for supercapacitors

This work investigates the impact of different ultrasonic treatment durations on the synthesis and electrochemical performance of NiZnCo2O4 (NZC) supercapacitor electrodes. Optimizing treatment to 20 min resulted in a uniform, compact NiZnCo2O4 layer with improved nanostructures, which increased the surface area and active sites for electrochemical reactions. X-ray diffraction (XRD) confirmed successful NiZnCo2O4 synthesis, revealing distinct crystalline phases of NiO, ZnCo2O4, and Co3O4, with improved crystallinity. Electrochemical tests, conducted using a 1.0 M KOH electrolyte, demonstrated that the NZC-2 electrode treated for 20 min achieved the highest 5.678 F/cm3 volumetric capacitance at 0.5 mA/cm2 current density along with 70.5 Wh/kg an energy density at 260 W/kg power density. The galvanostatic charge-discharge and cyclic voltammetry tests revealed that NZC-2 maintained superior charge-discharge efficiency, showing the longest discharge time at 1 mA/cm². Electrochemical impedance spectroscopy (EIS) measurements demonstrated that NZC-2 exhibited the lowest total impedance, thereby enhancing ion transport efficiency. The NZC-2/AC asymmetric supercapacitor showed excellent long-term stability, retaining 64.2% of its capacity after 20,000 charge-discharge cycles. It successfully powered a 1.2 V small fan, demonstrating its practical applicability. The results highlight the crucial importance of ultrasonic treatment in greatly improving the structural and electrochemical characteristics of NiZnCo2O4 electrodes, which opens up possibilities for the advancement of high-performance supercapacitors.

Insight into discharge of non-aqueous Li–O[formula omitted] battery using a three-dimensional electrochemical lattice Boltzmann model

Non-aqueous Li–O2 battery (NALiO2B) is a promising alternative to lithium-ion batteries, offering high theoretical energy density. However, its practical applications are hampered by limited understanding of the underlying mechanisms. In this study, a three-dimensional electrochemical lattice Boltzmann method is proposed to simulate the physical and electrochemical processes during NALiO2B discharge at the pore scale. The discharge performance of NALiO2B is evaluated for various electrode and electrolyte designs. It is found that the limited O2 diffusion within homogeneous electrodes is the primary cause of the declined reactive electrode surface area, the intensified electrochemical reaction (or overpotential), and finally the premature battery death. This issue can be mitigated by employing the hierarchical electrode BP2 with a bi-porous structure. The large pores in BP2 improve O2 transport to sustain the continuous electrochemical reaction process, thus enhancing the discharge capacity of NALiO2B. To further boost the rate capability of NALiO2B, BP2 is partially infiltrated with electrolyte to form the multiphase (MP) electrode, where air bubbles exist and serve as O2 reservoirs. These bubbles effectively provide adequate O2 to support the extensive O2 consumption during the fast electrochemical reaction at high current densities. Consequently, NALiO2B with MP demonstrates the satisfactory discharge capacity and rate capability. This study provides valuable insights into the complex physics and reaction kinetics behind NALiO2B discharge, which facilitates the optimization and development of NALiO2B.

Combustion Characteristics and Performance of Nanoflower Structure AlB2@AP Energetic Composites

ABSTRACT Boron-based solids have garnered significant attention due to their high calorific value. However, during combustion, the formation of boron oxide (B₂O₃) on the surface hinders the interaction between the oxidizing components and the internal active boron (B), thereby limiting its reactivity and combustion efficiency. Modifying boron-based solids represents an effective strategy for overcoming the limitations associated with fuel energy release efficiency. In this study, a shell-structured AlB₂@AP composite was designed and fabricated utilizing etching and recrystallization methods. The structure comprises AlB₂ as the core, B as the middle shell, and AP as the embedded outer shell. The key strategy involves employing an etching process to augment the reactive surface area of boron on the aluminum diboride surface, while also coating it with ammonium perchlorate (AP) to enhance the composite particles. This innovative approach demonstrates that the etching method can effectively utilize the boron present in AlB₂. The composite particles were characterized and analyzed for morphology employing a scanning electron microscope and X-ray techniques. Thermal analysis indicated that the decomposition stage of AP facilitated the oxidation of etched AlB₂, moreover, as the AP coating content increased, the temperature at which vigorous reactions initiated occurred earlier. In combustion experiments, the maximum combustion temperatures of AlB₂@10AP, AlB₂@20AP, and AlB₂@30AP increased by 36.4%, 15.1%, and 3.8%, respectively. The combustion formulation prepared with elemental boron exhibited different characteristics. The average combustion temperatures increased by 33.1%, 23.4%, and 14.4%, respectively. The combustion durations were reduced by 60.8%, 33.7%, and 31.7%, respectively. AlB2@AP is anticipated to further enhance its applications in propellants, explosives, and pyrotechnics.

Organic Coatings Reduce Dissolution Rate by an Order of Magnitude for Carbonate Minerals Produced by Marine Fish

AbstractMarine carbonate production and dissolution are important components of the global carbon cycle and the marine alkalinity budget. Global carbonate production by marine fish (ichthyocarbonate) has been estimated to be as high as 9.03 Pg CaCO3 yr−1; however, the fate of ichthyocarbonate is poorly understood. High magnesium concentrations in ichthyocarbonate would traditionally suggest rapid dissolution under current marine conditions, but a correlation between dissolution rate and mol%MgCO3 has not been observed. Here, we aim to determine the role of organic coatings on dissolution rates of ichthyocarbonate in marine environments. We applied a combination of petrographic, geochemical, and microCT approaches to assess the quantity and distribution of organic matter in ichthyocarbonate produced by two species of marine fish, the Gulf toadfish (Opsanus beta) and the Olive flounder (Paralichthys olivaceus). We show that organic matter, including external coatings and embedded organic material, is volumetrically significant, ranging from 8.5% to 32.3% of ichthyocarbonate by volume. Bleach oxidation of external organic matter coatings increased the dissolution rate of ichthyocarbonate by more than an order of magnitude, suggesting these coatings serve to reduce reactive surface area of the mineral fraction in ichthyocarbonate. Assuming that organic coatings do not influence sinking rates, external coatings extend the depth of ichthyocarbonate persistence in the water column by ∼12–15×. Therefore, organic coatings are an important determinant of the role of ichthyocarbonate in the marine carbon cycle.

Preparation of nano Cu-Mo2C interface supported on ordered mesoporous biochar of ultrahigh surface area for reverse water gas shift reaction

High conversion rate and selectivity are challenges for CO2 utilization through catalytic reverse water gas shift (RWGS) reaction. Herein, a novel mesoporous biochar (MB) supported Cu-Mo2C nano-interface was prepared by consecutive physical activation of coconut shells followed by carbothermal hydrogen reduction of bimetal. As compared with traditional carbon materials, this MB exhibited ultra-high specific surface area (2693 m2 g–1) and mesopore volume of mesopore (0.81 cm3 g–1) with a narrow distribution (2–5 nm), responsible for the high dispersion of binary Cu-Mo2C sites, CO2 adsorption and mass transfer in the reaction system. Moderate carbothermal reduction led to the sufficient reduction of Mo ion with carbon matrix of MB and dispersive growth of nano Cu-Mo2C binary sites (~ 6.1 nm) on the surface of MB. Cu+ species were formed from Cu0 via electron transfer and showed high dispersion with simultaneous boosted bimetal loading due to the strong interaction between nano Mo2C and Cu. These were advantageous to the intrinsic activity and stability of the Cu-Mo2C binary sites and their accessibility to the reactant molecules. Under the RWGS reaction conditions of 500 °C, atmospheric pressure, and 300,000 ml/g/h gas hour space velocity, the CO2 conversion rate over Cu-Mo2C/MB reached 27.74 × 10–5 molCO2/gcat/s at very low H2 partial pressure, which was more than twice that over traditional carbon supported Cu-Mo2C catalysts. In addition, this catalyst exhibited 99.08% CO selectivity and high stability for more than 50 h without a decrease in activity and selectivity. This study offers a new development strategy and a promising candidate for industrial RWGS.Graphical

Molecular properties of dissolved organic matter leached from microplastics during photoaging process

The occurrence of dissolved organic matter (DOM) derived from microplastics (MPs) and its effect on aquatic systems has attracted great interest recently. However, the photoaging effect on the molecular structure of MP-derived DOM (MP-DOM) remains unclear. This paper presents the characteristics of DOM leached from three commercial MPs, i.e., polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) under UV irradiation. With prolonged aging periods, the surface roughness and oxygen-containing groups on the surface of MPs increase as more DOM leachate is generated. Moreover, the dissolved organic carbon (DOC) content of the leached DOM from PET MPs varies from 0.52 mg/L to 2.25 mg/L, which is higher than PE and PP MPs, due to the larger increased surface reaction area and the cleavage of the benzene ring. According to the excitation-emission matrix and parallel factor analysis (EEM-PARAFAC), the plastic-derived protein/phenolic-like components (C1 and C3) in MP-DOM were changed into photo-induced humic-like components (C2), which were closely related to the intermediates during photo-oxidation. High-performance liquid chromatography-mass spectrometry (HPLC−MS) analysis further identified that the highest proportion of antioxidants (24.8 %∼34.6 %) was contained in MP-DOM. Plasticizers, intermediate additives, and antimicrobial agents were also detected in DOM leachate. Correlation analysis identified that the composition of leached DOM was positively correlated with the surface roughness, the carbonyl index (CI), and the chemical groups of MPs. Moreover, a partial least square structural equation model (PLS−SEM) analysis further verified that the change of morphology and the chemical structure of MPs could affect the DOM structures and fractions directly. This study provides an in-depth understanding of the composition of MP-derived DOM during the aging process, as well as a comprehensive environmental impact assessment of MPs.

Architecturing ultra-stable multi-dimensional MXene/MAX self-supporting electrode anchored with Low-Pt for efficient hydrogen evolution reaction in harsh environments

The design of self-supporting structure is particularly important to improve the stability and electrochemical performance of hydrogen evolution reaction electrode. Here, a facile strategy for building novel ultra-stable 0D-2D-3D integrated self-supporting electrode with high conductivity, sufficient diffusion channels and large reactive surface area was proposed. In the heterostructure, 2D Ti3C2Tx flakes in-situ synthesized on 3D network porous Ti3AlC2 surface which provides the multiple reactive surface areas and aggregation resistance to facilitating 0D ultrafine Pt nanoparticles uniform anchorage. Combined with structural characterization and first-principles calculations revealed that, the highly dispersed ultrafine Pt synergistically coupling strong metal-support interactions creates a unique multifunctional catalytic interface with high stability and atomic utilization efficiency of Pt to promote the HER in acidic and seawater. The resultant self-supporting electrode (support 0.48 wt% Pt) exhibits much superior activity to 10 % commercial Pt/C (loaded on foam nickel) in 0.5 M H2SO4 (55 mV@10 mA cm−2) and simulate seawater (196 mV@10 mA cm−2) while reducing the Pt usage by 15 times. Meanwhile, the electrode also illustrates outstanding stability under high current densities (100 h@100 mA cm−2). This study provides a new design idea for developing integrated self-supporting catalytic electrodes to meet the durability of hydrogen evolution reaction applications in harsh environments.

Enhancement of charge storage capacity in two-leg pseudo-spin ladder CaCu2O3 compound through Li-doping

Nanostructured 2-leg pseudo spin-ladder compound CaCu2O3 has been synthesized by chemical co-precipitation method and a significant improvement in its charge storage capacity has been realized through Li-doping. The fabricated electrode based on Li-doped CaCu2O3 exhibited higher specific capacitance of 321.26 F/g at 1.5 A g-1 when compared to that of 205.45 F/g for undoped CaCu2O3 system. Moreover, the electrode revealed an excellent cyclic stability (5000 cycles) with capacitance retention of 91.96 % of its initial value. An asymmetric supercapacitor fabricated using nano-flakes shaped Li-CaCu2O3 and activated carbon showed a notable energy density of 36.72 Wh/kg and power density of 1406 W/kg which maintains the energy density of 7.81 Wh/kg even at higher power density of 7031.25 W/kg. Among various Li-doped samples, 2.5 wt.% Li-CaCu2O3 exhibited the best storage capacity. This improvement has been attributed to the intrinsic off-stoichiometric (Ca0.86Cu2.14O2.93) and spin ladder structure of CaCu2O3 which allows Li to intercalate and improve the storage performance. Moreover, higher reactive surface area due to nano-flake morphology and porous structure of Li-CaCu2O3 may enhance the permeability of electrolytic ions, thereby improving the performance of the fabricated supercapacitor compared to undoped CaCu2O3 with rod-like morphology. These findings underscore the potential of Li-CaCu2O3 as a promising candidate material for fabricating supercapacitor devices.

Synthesis and application of biomass-based graphene oxide using microwave-assisted pyrolysis method

Graphene and related materials have excellent potential to revolutionise many emerging fields, but the large quantity synthesis using environmentally sustainable methods is still challenging. This work studies the synthesis of graphene oxide from food waste biochar with negatively charged properties, which is initially produced using microwave pyrolysis. The synthesised graphene oxide achieved 64.53 % carbon content, 345.79 m2/g surface area, 0.074 cm3/g micropore volume, large reactive surface area, and ribbon/banded organisation. The performance of carbon-based material is evaluated in the fabrication of a modified screen-printed carbon electrode (SPCE) for selective dopamine (DA) detection in the coexistence of ascorbic acid (AA) and uric acid (UA). The electrostatic interactions between the negatively charged biochar-based graphene oxide (BBGO) on the surface SPCE and opposite-charged dopamine assisted the oxidation potential with interfering species by electrostatic repulsion of AA and UA. This manuscript substantiates the resource recovery from organic materials and sustainable graphene oxide synthesis, underscoring their application in detecting positively charged species.

Effect of Nano Urea on Growth, Yield and Nutrient uptake of Finger Millet (Eleusine coracana L.)

Aim: The foliar application of nano urea is aimed at reducing the soil application of conventional urea. Nano fertilizers enhance crop growth and yield while enhancing nutrient uptake and reducing costs. They provide precise nutrient management, match crop growth stages, and offer an increased surface area for metabolic reactions. This boosts photosynthesis, leading to higher dry matter production and crop yield. Foliar application of nano urea (liquid) at tillering and booting stages in finger millet fulfills the nitrogen requirement and reflects higher crop productivity. Higher productivity of crops in a sustainable manner could be achieved by applying an appropriate combination of conventional fertilizers and nano fertilizers. Study Design: The experiment was laid out in split design with three replications. Place and Duration of Study: A field experiment was conducted in deep black soils at Agricultural Research Station, Siruguppa, during kharif 2022. Methodology: There were sixteen treatment combinations, consisting of different doses of nitrogen (no nitrogen, 50% RDN, 75% RDN and 100% RDN) with different concentrations of nano urea and conventional urea sprayed at tillering and booting stages for HR-13 variety of finger millet. Results: Application of 100% RDN has recorded significantly higher plant height, tillers plant-1, total dry matter accumulation, grain yield and straw yield (129.82 cm, 10.10, 36.17 g plant-1, 36.87 q ha-1 and 71.72 q ha-1, respectively) in comparison to no nitrogen and 50% RDN. However, 75% RDN (123.04 cm, 9.61, 34.02 g plant-1, 34.84 q ha-1 and 68.01 q ha-1, respectively) found on par with 100% RDN. Among foliar nitrogen, spray of nano urea @ 4 ml L-1 recorded significantly higher plant height (121.59 cm), tillers plant-1 (9.37), total dry matter accumulation (33.16 g plant-1), grain yield (31.97 q ha-1) and straw yield (65.52 q ha-1) compared to 0.5% and 1% conventional urea. However, nano urea @ 2 ml L-1 was on par with 4 ml L-1 nano urea and 1% conventional urea. Similar trend was recorded with regard to nutrient uptake by finger millet. Conclusion: Foliar application of nano urea reduced the dosage of conventional urea by 25 per cent.

Nanostructured thin film SrCo0.8Nb0.1Ta0.1O3-δ cathode for low-temperature solid oxide fuel cells

Nanostructured perovskite-type cathodes are considered essential for the realization of high-performance solid oxide fuel cell (SOFC). However, perovskite-type cathode materials demonstrating high electrochemical performance in the low-temperature operating region below 600° are limited. SrCo0.8Nb0.1Ta0.1O3-δ (SCNT) has been identified as a material that exhibits exceptional performance even in the low-temperature region of 500 °C. This paper investigates the growth behavior and electrochemical properties of SCNT thin films for SOFC cathode applications. Pulsed laser deposition (PLD) was employed to fabricate SCNT films under varying chamber pressures: 5 mTorr, 75 mTorr, and 150 mTorr. Systematic analysis through X-ray diffraction and X-ray photoelectron spectroscopy indicates that the structural factors of PLD perovskite oxide nanostructures, such as grain size, porosity, and in-plane connectivity, are intricately influenced by deposition pressure without affecting crystallinity and chemical composition. The findings demonstrate that achieving desired electrochemical properties of the nanostructured PLD perovskite oxide necessitates specific optimal deposition conditions for these structural parameters. Electrochemical assessments revealed an optimal nanostructure achieved with 1200 nm at 75mTorr, demonstrating enhanced power density due to increased active reaction surface area, which significantly reduced resistances in ohmic and polarization. Excessive thickness, however, led to performance decline due to film delamination. Integration of optimized SCNT films into an anodic aluminum oxide supported thin film SOFC exhibited 907 mW/cm2 of peak power density at 550 °C.

Reduced Surface Area for the Oxygen Reduction Reaction in Porous Electrode via Electrical Conductivity Relaxation.

Oxygen reduction reaction (ORR) performance of porous electrode is critical for solid oxide fuel cells (SOFCs). However, the effects of gas diffusion on the ORR in porous media need further investigation, although some issues, such as nonthermal surface oxygen exchange, have been attributed to gas diffusion. Herein, La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) with various porosity, pore radii and gas permeability were investigated via the electrical conductivity relaxation method and analysed using the distributed of characteristic time (DCT) model. The ORR is revealed with three characteristic times, which are gas diffusion, oxygen exchange via the surface corresponding to small pores, and oxygen exchange to large pores. Gas diffusion delays the oxygen surface exchange reaction, resulting in very low chemical oxygen surface exchange coefficient compared with that obtained with dense sample under the assumption that all the surfaces are active for the ORR. Reduced surface area is thus defined to quantitatively represent the gas diffusion effects. The reduced surface area increases with increasing gas permeability, demonstrating the importance of electrode engineering for fast gas transport. Moreover, reduced surface area is suggested for replacing the specific surface area to calculate the electrode polarization resistance using the ALS model.

Hierarchical Pore Structure Composite Electrode by Electrospinning for Dendrite‐free Zinc‐Based Flow Battery

AbstractIn the pursuit of sustainable energy solutions, zinc‐based flow batteries stand out for their potential in large‐scale energy storage, offering a blend of cost efficiency and safety. Although the porous electrode provides an increased specific surface area for reaction, the non‐uniform deposition of zinc, attributed to uneven concentration distribution within the porous electrode, has been a pivotal issue in accelerating the formation of zinc dendrites, which hinders the enhancement of energy density. A composite electrode with a strategic hierarchical pore structure has been developed with aligned nitrogen‐doped carbon fibers and traditional carbon felt. This structure takes advantage of the large pores of the carbon felt for efficient through‐flow paths, ensuring higher flow rates, while the dual‐scale pores within the electrospun film enhance mass transfer and increase the specific surface area. At 320 mA cm−2, it achieved an ≈11.4% improvement in the battery's energy efficiency. Moreover, the nitrogen doping and the optimized reaction uniformity within the composite electrode have been instrumental in reducing the generation of zinc dendrites. The battery, integrated with the innovative composite electrode, maintained an energy efficiency of 59.2% at 320 mA cm−2 after 300 cycles, which is a substantial improvement in operational longevity.

Fast and green synthesis of battery-type nickel-cobalt phosphate (NxCyP) binder-free electrode for supercapattery

Binder-free electrodes are increasingly important in energy storage technologies owing to the direct growth of active material on conducting substrates without binders, providing a shorter conduction channel for rapid electron transport. Various methods have been employed to synthesize binder-free electrodes, but most approaches often prove time-consuming, and some require elevated synthesis temperatures. Herein, a rapid and eco-friendly microwave-hydrothermal method was introduced to fabricate the battery-type nickel–cobalt phosphate (NxCyP) binder-free electrodes for supercapattery. The use of microwave accelerates heating and reduces the activation energy of the reaction, resulting in shorter synthesis time and lower reaction temperature. The NxCyP electrodes were fabricated at different parameters, such as temperature (90–200 °C), time (5–20 min), and Ni:Co precursor ratios (4:0, 3:1, 2:2, 1:3, 0:4). The optimization study was carried out via Design Expert v13 software, and the optimized parameter was the temperature of 123.5 °C, duration of 10.5 min, and Ni:Co of 2:2, namely N2C2P binder-free electrode. The N2C2P electrode exhibited larger flake- and flower-like morphologies, providing more space for electrolyte ion diffusion and a larger surface area for faradaic reactions. Consequently, it demonstrated outstanding electrochemical performance by displaying a high specific capacity (1699.7C/g at 3 mV/s), superior capacity retention, and the lowest resistances than other NxCyP electrodes. As a result, the N2C2P//AC supercapattery was created by merging it with an activated carbon (AC) electrode, showing a superior energy density (213.0 Wh/kg) and high electrochemical stability with 92.9 % retention after 3000 cycles at 10 A/g.