Enhanced Electrocatalytic Activity of Cobalt-Doped Ceria Embedded on Nitrogen, Sulfur-Doped Reduced Graphene Oxide as an Electrocatalyst for Oxygen Reduction Reaction

Amorphous Cobalt-Impregnated Nitrogen-Doped Carbon Encapsulation Nanochain Enhances Long-Lasting Electrochemical Water Splitting

Electrochemical water splitting (EWS) is a promising way to attain H2, which has been deemed an ideal substitution for fossil fuels because of renewable and eco-friendly benefits. Developing an amorphous-based simple and structurally flexible non-noble catalyst to offer high performance for commercial applications has become a current interest. Amorphous cobalt-anchored nitrogen-doped carbon nanoparticles (Co@NC-NPs) were designed to have a low overpotential and Tafel as a bifunctional electrocatalyst (HER - 142 mV/80 mV dec-1 and OER - 250 mV/72 mV dec-1) to achieve 10 mA cm-2 in 1.0 KOH. FE-SEM and HR-TEM described the interconnected nanochain morphology and purity of Co@NC-NPs electrocatalyst, which were confirmed by EDX and elemental mapping. In a full cell water electrolyzer, Co@NC-NPs(+,-) may act as an anode and cathode electrode material to achieve 1.60 V @ 10 mA cm-2 in a wide pH. The efficient Co@NC-NPs are stable for 100 h without obvious recession. In solar cell applications, Co@NC-NPs(+,-) catalyst was employed as both positive and negative terminals and evolved enormous bubbles of O2 and H2. As previously mentioned, we covered the amorphization strategy with the optimistic role of structural flexibility and defects to enrich the active sites to improve the electrocatalytic stability. As a promising opinion, the amorphous electrocatalyst provides ultraefficiency for forthcoming developments in EWS.

Enhanced efficiency of photocatalytically synthesised Co3+/Co2+-incorporated CeO2/SnO2 nanocomposite and supercapacitor studies

The photochemical reduction approach, distilled H2O with PriOH as the solvent medium, was used to create and characterise the conversion of Co3+ to Co2+ integrated on CeO2/SnO2. The PXRD, IR, SEM, HR-TEM, VSM, and XPS results show that the materials generated have appropriate crystallisation form and retain the hollow spherical structure of Co-CeO2/SnO2. The performance of several UV-light energetic photocatalysts and the reaction pathways for inorganic complex degradation are addressed, emphasising the main elements contributing to their mineralisation. Reaction mechanisms, identification and quantification of degradation intermediates, and effects of reactive active species were described and analysed for each modelled target inorganic pollutant category. The ternary (Co3+/Co2+)/CeO2/SnO2 materials were hypothesised to improve the photocatalytic activity by increasing the transport rate of eCB- impurities as a result of accelerating the practical separation of electron-hole (e-/h+) pairs. Then, it exhibits high cycling stability by successfully reducing the pulverisation of Co-CeO2/SnO2 electrode materials due to volume expansion and a high specific capacity of 827 F g-1(1 A g-1) while maintaining a high current density of 5 A g-1. GCD and impedance spectroscopy studies were also carried out to analyse charge-discharge cycles and sample stability. This exceptional electrochemical performance suggests that Co-CeO2/SnO2 are promising for high-performance energy storage systems.

Co-Doped CeO2/Activated C Nanocomposite Functionalized with Ionic Liquid for Colorimetric Biosensing of H2O2 via Peroxidase Mimicking

Hydrogen peroxide acts as a byproduct of oxidative metabolism, and oxidative stress caused by its excess amount, causes different types of cancer. Thus, fast and cost-friendly analytical methods need to be developed for H₂O₂. Ionic liquid (IL)-coated cobalt (Co)-doped cerium oxide (CeO₂)/activated carbon (C) nanocomposite has been used to assess the peroxidase-like activity for the colorimetric detection of H₂O₂. Both activated C and IL have a synergistic effect on the electrical conductivity of the nanocomposites to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). The Co-doped CeO₂/activated C nanocomposite has been synthesized by the co-precipitation method and characterized by UV-Vis spectrophotometry, FTIR, SEM, EDX, Raman spectroscopy, and XRD. The prepared nanocomposite was functionalized with IL to avoid agglomeration. H₂O₂ concentration, incubation time, pH, TMB concentration, and quantity of the capped nanocomposite were tuned. The proposed sensing probe gave a limit of detection of 1.3 × 10^-8 M, a limit of quantification of 1.4 × 10^-8 M, and an R² of 0.999. The sensor gave a colorimetric response within 2 min at pH 6 at room temperature. The co-existing species did not show any interference during the sensing probe. The proposed sensor showed high sensitivity and selectivity and was used to detect H₂O₂ in cancer patients' urine samples.