Ionics最新文献

Proton exchange membrane fuel cells (PEMFCs) are promising for clean energy generation, where the design of the flow channels is crucial for uniform reactant distribution on the catalyst surface. This study involves designing a divergent parallel flow field and comparing its performance with a single serpentine flow channel. The findings indicate that the divergent parallel flow field enhances peak power density by 23% compared to the serpentine flow field under same operating conditions. A parametric study was conducted on the divergent parallel flow channel, varying cell temperature, anode humidification temperature (AHT), cathode humidification temperature (CHT), anode flow rate (AFR), cathode flow rate (CFR), and operating pressure (OP). The optimized conditions found are a cell operating temperature (COT) of 70 °C, AHT of 70 °C, CHT of 60 °C, AFR of 300 sccm, CFR of 350 sccm, and OP of 3 bar. The PEMFC delivered a MPD of 0.5408 W·cm² at these optimized conditions. The results show the potential of the divergent parallel flow field design for greatly improved PEMFC performance.

Reduced graphene oxide (rGO) was synthesized via a simple and eco-friendly hydrothermal method using high-purity precursors. The novelty of this study lies in the comprehensive characterization and application of rGO for dual-functional performance: energy storage and water purification. The formation of rGO was confirmed through XRD, FTIR, and FT-Raman analysis, revealing an average crystallite size of 10 nm, calculated using the Scherrer formula. Advanced XPS analysis verified the oxidation state and chemical composition of rGO. The microstructure, elemental composition, and optical properties were thoroughly examined using FE-SEM with EDX, HR-TEM, UV–Vis-DRS, and PL spectroscopy. Electrochemical studies demonstrated rGO’s pseudocapacitive nature, achieving a high specific capacitance of 398 Fg⁻¹ (10 mVs⁻¹) with excellent cyclic stability, retaining 83% of its initial capacity after 2000 cycles. Notably, rGO exhibited remarkable photocatalytic activity for degrading Congo red (CR) and crystal violet (CV) dyes under UV-light irradiation, achieving high degradation efficiencies. This dual-functional performance underscores the potential of GO and rGO in sustainable energy storage applications, efficient water treatment, and critical environmental challenges.

Although pure BiPO₄ and ZnWO₄ exhibit limited degradation efficiency for Rhodamine B (RhB), methyl blue (MB), and basic fuchsin (BF), the degradation rates of the BiPO₄ and ZnWO₄ composite (2ZW:BP) were significantly enhanced. Specifically, the rates were 133.8 and 99.1 times higher for RhB, 6.33 and 18.51 times higher for MB, and 18.3 and 19.12 times higher for BF, compared to BiPO₄ and ZnWO₄, respectively. The 2ZW:BP composite achieved degradation efficiencies of 91.4%, 92.8%, and 96.5% for RhB, MB, and BF within 100 min, 5 h, and 3 h under irradiation with a 5W LED lamp. Scanning electron microscopy (SEM) analysis revealed that although both BiPO₄ and ZnWO₄ exhibit rod-like morphologies, the ZnWO₄/BiPO₄ heterostructures formed through one-step hydrothermal recombination were sheet-like. This morphological transformation was accompanied by increased oxygen vacancies, enhanced charge-hole separation efficiency, a broader light absorption range, and improved dye adsorption rates, thereby significantly enhancing the photocatalytic performance of ZnWO₄/BiPO₄.

Energy is of paramount importance in our everyday lives and energy storage technologies are needed to solve the global energy problems largely. In this work, manganese oxide (Mn_xO_y) films were electrodeposited chronoamperometrically on stainless steel (ss) and fluorine doped tin oxide (FTO) substrates at different step potentials. The effect of the deposition potential and temperature treatment on the phase and supercapacitive properties of the Mn_xO_y were studied. At a step potential of less than 1.2 V no deposition was achieved while at 1.2 V, the as deposited oxide showed a bit of amorphousness with vestiges of Mn(OH)₂ as evident from the x-ray diffraction (XRD) studies. At higher potentials (1.4 and 1.6 V), the as-deposited oxide appeared as the MnO₂ phase. However, higher temperature treatment (600 °C) of all the deposits obtained at the various potentials resulted to Mn₂O₃ phase. The scanning electron microscopy (SEM) of the films showed that the as-deposited and the 400 °C annealed electrodes are porous while they become more compact and cemented at 600 °C. The obtained bandgap energies ranged from 1.26–2.65 eV for the films deposited at differing potentials and heat treatments. The electrochemical analysis shows the highest specific capacitance of 455 F g⁻¹ for the 1.2 V@400 °C electrode while the Mn₂O₃ electrodes are more stable. The electrodes exhibited good potentials for supercapacitor application.

The CoMn-LDH/MXene composite was fabricated via hydrothermal synthesis, with nanoscale CoMn-LDH encapsulated on MXene through surface functional groups. This effectively prevents CoMn-LDH aggregation and improves its electrochemical properties. The effects of cobalt-manganese ratio, reaction time, and temperature on the electrochemical properties of CoMn-LDH were explored, as well as the impact of MXene addition on CoMn-LDH composite properties. A comparative analysis of the structural features of pure CoMn-LDH and the composite CoMn-LDH/0.08MXene reveals that the latter exhibits a more pronounced hierarchical structure. Composite CoMn-LDH/0.08MXene has a specific capacity of 1517.8 C-g⁻¹ at a current density of 1 A g⁻¹, significantly surpassing the 1186.8 C·g⁻1 achieved by pure CoMn-LDH. The asymmetric supercapacitor constructed with this composite material reached an energy density of 48.5 Wh·kg-1 and a power density of 755.3 W·kg⁻¹, retaining 95% of its capacity after 5000 charge/discharge cycles.The synergistic effect of CoMn-LDH and MXene enhances the capacitance and stability of the CoMn-LDH/0.08MXene composite capacitor. The simplicity of the preparation process, coupled with the excellent performance of the CoMn-LDH/MXene composites, suggests that they have considerable potential for use in advanced energy storage applications. 

The state of charge (SOC) of lithium-ion batteries is vital for efficient energy management and prolonging battery lifespan. To improve the accuracy of SOC estimation for lithium-ion batteries, this paper proposes an improved genetic algorithm (IGA) and a nonlinear autoregressive particle filter (NARXNN-PF: nonlinear autoregressive neural network with exogenous inputs integrated with particle filter) for parameter identification and SOC estimation, respectively. Based on the dual-polarization model, parameter identification is achieved by minimizing terminal voltage errors while accounting for uncertainties in initial conditions and measurement errors. Using the accurately identified model parameters, the NARXNN-PF is applied for online estimation. The SOC predictions generated by the NARXNN serve as prior information for the particle filter. During particle weight updates, the predictive capability of the NARXNN is leveraged to refine particle weights, optimizing their distribution and thereby enhancing the algorithm’s overall accuracy and robustness.

There is an urgent need for efficient and sustainable solutions to tackle the escalating issues of wastewater pollution and microbial resistance. To this end, a novel quaternary chitosan-incorporated CeO₂/ZrO₂/Bi₂O₃ (CS-TMO) composite was made using a co-precipitation approach and assessed for its dual functionalities in wastewater treatment and antibacterial efficacy. The structural and chemical properties of the composite were analyzed using XRD, XPS, SEM, and BET studies which revealed that CS-TMO exhibited nanoflake morphology with surface area of 27.77 m²/g, and a pore volume of 0.003 cc/g. The composite photocatalytically degraded 95% of malachite green (MG) in 180 min and 92% of Acid Blue 113 (AB 113) in 240 min when illuminated with solar light. The degradation process was greatly improved under ideal conditions, which included a catalyst dosage of 9 mg, a pH of 7 for MG and 9 for AB113, and the presence of electrolytes based on carbonates. Complete mineralization into CO₂ and H₂O was confirmed using ESI–MS analysis, which explained the breakdown mechanisms. Three cycles of reusability testing revealed that the material maintained its integrity with no loss of efficiency. Additionally, antimicrobial experiments showed that it effectively killed Escherichia coli bacteria and Aspergillus niger and Candida albicans fungi. These results highlight the possibility of CS-TMO composites as environmentally friendly materials for controlling microbes and restoring wastewater.

PtPd bimetallic catalysts have garnered significant attention in the field of hydrogen production via water electrolysis due to their excellent catalytic performance and promising application prospects. There is an urgent need to develop a direct synthesis method for highly efficient and stable PtPd-based nanocatalysts. In this study, a PtPd bimetallic nanoparticle/biochar composite catalyst was synthesized by combining the impregnation method and high-temperature carbonization in situ co-reduction techniques. Leveraging the micro-confinement effect of the biomass cell membrane/wall structure, the PtPd bimetallic nanoparticles were in situ anchored onto the surface of the biomass nitrogen-doped carbon material through the action of ionic chemical bonds. The addition of Pd modulated the electronic structure of Pt, and the synergistic interaction between Pt and Pd, along with the interaction between the PtPd alloy and the C-N support, generated multiple active sites, significantly enhancing the electrocatalytic hydrogen evolution reaction (HER) efficiency. The synthesized PtPd@C-N catalyst exhibited excellent hydrogen evolution activity and long-term stability in 0.5 M H₂SO₄. Among them, Pt₆₅Pd₃₅@C-N achieved a mass activity of 3.56 A/mg at an overpotential of 50 mV, far surpassing that of Pt@C-N, Pd@C-N prepared under the same conditions and is 16 times higher than the mass activity of commercial Pt/C. This study provides a new idea for the preparation of binary alloy nanocatalysts and demonstrates potential application prospects in the fields of energy conversion and storage.

This study explores the demethylation of methylene blue in an acidic pH, utilizing a spent cathode from Li-ion batteries. The spent cathode has a composition of LiMn₂O₄ and a pzc close to pH = 2.1. In contact with methylene blue in an acidic medium (pH = 2), the spent cathode adsorbed and demethylated methylene blue to form thionine. This was confirmed by UV–Vis and ESI measurements of the resulting solutions. The intermediate m/z = 300 was crucial for proposing the demethylation mechanism that is similar to a demethylation mechanism catalyzed by hemoproteins. FTIR measurements confirmed the adsorption of methylene blue onto the spent cathode. The rise in pH observed during demethylation can explain the incomplete degradation of methylene blue stopping at the thionine stage. Consequently, the reaction involving the spent cathode of the Li-ion battery based on LiMn₂O₄ may be applicable to the demethylation of other molecules in future research.

The practical application of Fe₂O₃ as the anode material in LIBs is greatly hindered by several severe issues, such as drastic capacity falloff, short cyclic life, and huge volume change during the charge/discharge process. To tackle these limitations, cobalt-doped mesoporous Fe₂O₃ nanoparticles were successfully synthesized using the hydrothermal method. The mesoporous structure can alleviate the volume expansion and stress during the charge–discharge process and improve cycle stability. When Co-Fe₂O₃(1:1) is used as the anode of a lithium-ion battery, the first discharge capacity is 873.20 mAh g⁻¹ at a current density of 50 mA g⁻¹. Under a current density of 200 mA g⁻¹, after 100 charge–discharge cycles, the specific discharge capacity of Co-Fe₂O₃(1:1) reached 576.12 mAh g⁻¹, with the Coulombic efficiency still maintained at 97.83%. Therefore, Co-Fe₂O₃(1:1) has great potential as an anode material for high-performance lithium-ion batteries.