High-performance anti-corrosion behavior of graphene oxide decorated nickel coating by novel ultrasonic-assisted supercritical-CO2 electrodeposition approach

Supercritical CO2 mediated construction of aluminium waste recovered γ-Al2O3 impregnated Dracaena trifasciata biomass-derived carbon composite: A robust electrocatalyst for mutagenic pollutant detection

Inspired by the waste-to-wealth concept, we have recovered the gamma phase aluminium oxide nanoparticles (γ-Al2O3 NPs) from waste aluminium (Al) foils and fabricated a composite with Dracaena trifasciata biomass-derived activated carbon matrix (DT-AC) using supercritical carbon-di-oxide (SC-CO2) pathway. The prepared samples are characterized altogether by various micro- and spectroscopic analyses. Based on the results, the recovered γ-Al2O3 NPs are well impregnated in the DT-AC surface by the action of the microbubble effect from the SC-CO2. The higher D-band and ID/IG value of 1.07 in the Al2O3/DT-AC nanocomposite indicate increased defects and the amorphous nature of the carbon materials. The effect of scan rate (ν) demonstrated greater linearity in ν1/2 vs peak current in the electrochemical detection study of the mutagenic pollutant 4-(methylamino) phenol hemi sulfate, showing a quasi-reversible electron transfer process undergoing diffusion-controlled kinetics. Furthermore, the limit of detection is determined to be 3.2 nM L-1 with an extensive linear range, spanning from 0.05 to 618.25 µM/L. The incredible sensitivity of 2.117 μA μM-1 cm-2, along with excellent selectivity, repeatability, and stability, is observed. Further, the respectable recovery percentage of 98.61 % in the environmental water sample is perceived. The observed outcomes suggest that the prepared Al2O3/DT-AC composite performs as an excellent electrocatalyst material, and the processing techniques used are thought to be sustainable in nature.

Novel Design of Perovskite-Structured Neodymium Cobalt Oxide Nanoparticle-Embedded Graphene Oxide Nanocomposites as Efficient Active Materials of Energy Storage Devices

In recent years, electrochemical supercapacitors are expected to represent the future of energy storage device technology. Specifically, the excellent electrochemical performance with long cycle life, high energy, and power density is considered an essential criterion for commercial applications. Herein, we constructed a novel composite of neodymium cobalt oxide-encapsulated graphene oxide nanocomposite (NCO/GO) via a simple and robust method for a symmetric supercapacitor (SSC) device. The prepared samples were securitized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and Brunauer-Emmett-Teller analysis. The as-synthesized NCO/GO is deposited on nickel foam (NF) and used as a supercapacitor electrode (NCO/GO/NF), which exhibits superior specific capacitance (Cs) of 1080.92 F g-1 at 1 A g-1 and fantastic cycling life with ∼89.42% retention after 10,000 cycles at 10 A g-1 in 1.0 M KOH aqueous electrolyte. A tremendous electrochemical performance of the hybrid nanocomposite electrode is obtained from the good redox activity and synergistic effects of the NCO spherical-like nanoparticles combined with the GO nanosheets. Furthermore, the assembled SSC device delivers significantly enhanced power density (932.93 Wh kg-1) and energy density (210.42 mWh kg-1). Moreover, the SSCs exhibit excellent cycling stability with ∼82.19% capacity retaining over 10,000 charge/discharge cycles. Remarkably, a 1.8 V red light-emitting diode (LED) can be lit up for more than 10 min by series connection SSCs. Thus, the obtained results indicated that the NCO/GO/NF//NCO/GO/NF symmetric device has a robust and cost-effective electrode material for high-performance supercapacitor systems.

A biogenesis construction of CuO@MWCNT via Chenopodium album extract: an effective electrocatalyst for synaptic plasticity neurodegenerative drug pollutant detection

Clioquinol (CLQ) is one of the most toxic halogenated neurodegenerative drugs, and its synaptic plasticity effect directly affects human health and the environment. Cupric oxide (CuO) is an ideal electrocatalyst owing to its earth-abundance, non-toxic nature, and cost-effectiveness. Since phenolate oxygen and pyridine nitrogen in CLQ act as an electron donor and pave the way for detection with Cu2+ ions in the CuO. Designing the architecture of CuO with a multi-walled carbon nanotube (MWCNT) is a sensible strategy to improve the electrochemical activity of the developed sensor. Inspired by the bio-synthesis and green processing, we have demonstrated the in-situ synthesis of CuO nanosphere-decorated MWCNT by Chenopodium album leaf extract through a sonochemical approach and explored its electrochemical sensing performance toward CLQ. The physical comprehensive characterization of prepared nanocomposite was investigated by various microscopic and spectroscopic techniques. For comparison studies, the CuO nanosphere was prepared by the same preparation process without MWCNT. Based on the physical characterization outcomes, the morphological nature of CuO was observed to be a sphere-like structure, which was decorated on the MWCNT with an average crystallite size of 16 nm (± 1 nm). Based on the electrochemical studies, the fabricated nanocomposite exhibits a wider linear range of 0.025-1375 μM, with a minimum detection limit of 4.59 nM L-1 toward CLQ. The viability examination on the biological matrix obtained considerable spike recoveries.

A new class of layered Bi2O2S nanopetals by one-pot supercritical-CO2 approach: A reliable electrocatalyst for analgesic bioflavonoid detection

Nanomaterials frequently draw a lot of interest in a variety of disciplines, including electrochemistry. Developing a reliable electrode modifier for the selective electrochemical detection of the analgesic bioflavonoid i.e., Rutinoside (RS) is a great challenge. Here in, we have explored the supercritical-CO₂ (SC-CO₂) mediated synthesis of bismuth oxysulfide (SC-BiOS) and reported it as a robust electrode modifier for the detection of RS. For a comparison study, the same preparation procedure was carried out in the conventional approach (C-BiS). The morphology, crystallography, optical, and elemental contribution analyses were characterized to understand the paradigm shift in the physicochemical properties between SC-BiOS and C-BiS. The results exposed the C-BiS had a nano-rod-like structure with a crystallite size of 11.57 nm; whereas the SC-BiOS had a nano-petal-like structure with a crystallite size of 9.03 nm. The B_2g mode in the optical analysis confirms the formation of bismuth oxysulfide by the SC-CO₂ method with the Pmnn space group. As an electrode modifier, the SC-BiOS achieved a higher effective surface area (0.074 cm²), higher electron transfer kinetics (0.13 cm s^-1), and lower charge transfer resistance (403 Ω) than C-BiS. Further, it provided a wide linear range of 0.1-610.5 μM L^-1 with a low detection and quantification limit of 9 and 30nM L^-1 and an appreciable sensitivity of 0.706 μA μM^-1 cm^-2. The selectivity, repeatability, and real-time application towards the environmental water sample with a recovery of 98.87% were anticipated for the SC-BiOS. This SC-BiOS unlocks a fresh avenue to construct a design for the family of electrode modifiers utilized in electrochemical applications.

In-situ fabrication of manganese ferrite grafted polyaniline nanocomposite: A magnetically reusable visible light photocatalyst and a robust electrode material for supercapacitor

Herein, we reported the in-situ preparation of manganese ferrite (MnFe₂O₄) grafted polyaniline (Pani), a magnetic nanocomposite for the potential visible light photocatalytic material as well as electrode material for supercapacitor. The physical characterization of the prepared nanoparticle and nanocomposite was examined with various spectroscopic and microscopic analyses. The peaks observed in the X-ray diffraction study confirm the face-centered cubic phase of MnFe₂O₄ nanoparticles with a grain size of ∼17.6 nm. The surface morphology analysis revealed the uniform distribution of spherical-like MnFe₂O₄ nanoparticles on the surface of Pani. The degradation of malachite green (MG) dye under exposure to visible light was investigated using MnFe₂O₄/Pani nanocomposite as a photocatalyst. The results exposed the faster degradation of MG dye was accomplished by MnFe₂O₄/Pani nanocomposite than MnFe₂O₄ nanoparticles. The energy storage performance of the MnFe₂O₄/Pani nanocomposite was analyzed through cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy analyses. The results exposed that the MnFe₂O₄/Pani electrode achieved a capacitance of 287.1 F/g than the MnFe₂O₄ electrode (94.55 F/g). Further, the respectable capacitance of 96.92% was achieved even after 3000 repetitive cycles stability . Based on the outcomes, the MnFe₂O₄/Pani nanocomposite can be suggested as a promising material for both photocatalytic and supercapacitor applications.

Recovery of Al2O3 from hazardous Al waste as a reinforcement particle for high-performance Ni/Al2O3 corrosion resistance coating via ultrasonic-aided supercritical-CO2 electrodeposition

The unprocessed dumping of aluminium wastes in the landscape leads to generation of heat and toxic gases, which are detrimental to the ecosystem. Motivated by the waste-to-wealth notion, we demonstrated the recovery of aluminium oxide nanoparticles (Al₂O₃NPs) from domestic aluminium wastes via a sonochemical approach and synthesis of nickel/aluminium oxide (Ni/Al₂O₃) coating via ultrasonic-coupled supercritical carbon dioxide (US-SC-CO₂) electrodeposition method for higher corrosion resistance performance. The physical characterization and material confirmation of prepared films were examined by microscopic and various spectroscopic techniques. The electrochemical corrosion resistance studies were explored via potentiodynamic polarization and electrochemical impedance spectroscopy techniques. Based on the results, the US-SC-CO₂ strategy exposed an improved distribution of Al₂O₃ NPs assimilation in Ni matrix, higher corrosion resistance, and microhardness. The integration of ultrasonic irradiation into the SC-CO₂ process promises an enhanced coating quality. Thereby, the novel US-SC-CO₂ approach for Ni/Al₂O₃ synthesis is expected to achieve a sustainable green impact in real-world applications.

Investigation on Microstructure, Nanohardness and Corrosion Response of Laser Cladded Colmonoy-6 Particles on 316L Steel Substrate

316L steel is predominantly used in manufacturing the components of high-pressure boilers, heat exchangers, aerospace engines, oil and gas refineries, etc. Its notable percentage of chromium offers resistance against corrosion and is mostly implemented in harsh environments. However, long-term exposure to these components in such environments can reduce their corrosion resistance property. Particularly at high temperatures, the oxide film formed on this type of steel reacts with the chloride, sulfides, sulfates, fluorides and forms intermetallic compounds which affect its resistance, followed by failures and losses. This work is focused on investigating the hardness, microstructure and corrosion resistance of the laser cladded Colmonoy-6 particles on the 316L steel substrate. The cladded specimens were dissected into cubic shapes and the microstructure present in the cladded region was effectively analyzed using the FESEM along with the corresponding EDS mapping. For evaluating the hardness of the cladded samples, the nanoindentation technique was performed using the TI980 TriboIndenter and the values were measured. The potentiodynamic polarization curves were plotted for both the substrate and clad samples at 0, 18, 42 and 70 h for revealing the corrosion resistance behavior. In addition, the EIS analysis was carried out to further confirm the resistance offered by the samples. The surface roughness morphology was evaluated after the corrosion process using the laser microscope, and the roughness values were measured and compared with the substrate samples. The result showed that the cladded samples experience greater hardness, lower values of surface roughness and provide better corrosion resistance when compared with substrate samples. This is due to the deposition of precipitates of chromium-rich carbide and borides that enhances the above properties and forms a stable passive film that resists corrosion during the corrosion process.