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Carbonaceous materials with closed pore structures have emerged as promising anodes for sodium-ion batteries. However, the rational design of closed pores and the investigation of their underlying sodium storage mechanisms face significant challenges. Herein, PVDF-derived pyrolytic carbon (PFC) with abundant open ultra-micropores and uniform pore size of 0.55 nm was chosen as the carbon matrix to construct a closed pore model to elucidate the sodium storage process in the closed pores. The transformation of ultra-micropores into closed pores was achieved with the assistance of polypropylene (PP), where the light aromatic compounds derived from PP can be deposited at the open pore entrance of the PFC during the pre-oxidation process, and subsequently pyrolyzed to a carbon layer in the carbonization stage, thus converting the open pores into closed pores. The obtained closed pore enriched carbon (PFCC@PP) showed a noticeable low-potential plateau region in the charge/discharge curve and an improved reversible capacity of 309.3 mA h g−1 with a high initial coulombic efficiency of 87.8%. When coupled with the O3-NaNi1/3Fe1/3Mn1/3O2 cathode, the assembled Na ion full cell realized a high energy density of 239.2 Wh kg−1 besides the remarkable rate capability. Additionally, theoretical calculations further validated the significant role of closed pores with optimal pore size in efficient Na ion storage. This work not only provides an interesting model for investigating closed-pore structures but also offers new insights into the rational design of carbon materials for advanced energy storage technology. [ABSTRACT FROM AUTHOR]

This study describes the development of a new ITO-based electrode used for the electrochemical determination of N-acetyl-l-cysteine (NAC). The electrode system relies on in situ grown CuO nanostructures over the ITO substrate, which provide a relatively greater contact and enables effective electron facilitation during the electrocatalytic oxidation of NAC in an aqueous medium. In situ growth of the CuO nanostructures was achieved using a simple hydrothermal process with the application of succinic acid as an effective growth template. The grown layer of CuO possessed a dense population of highly ordered nanostructures with a high degree of structural uniformity. The study evaluates the potential of the newly developed ITO-based electrode against the bare GCE and an electrode modified via the direct deposition of the same CuO nanostructures synthesised under similar hydrothermal conditions. The electrochemical oxidation of NAC over the newly developed electrode demonstrated low-over potential value and good working linearity in the range from 0.01 to 0.28 μM. The electrode system was found to be sensitive up to 1.2 × 10−3μM (S/N = 3) with charge transfer co-efficient (α) and diffusion co-efficient (D) values of 0.65 and 1.62 × 10−2 cm2 s−1, respectively. Moreover, the developed electrode system demonstrated excellent working capability when utilised for the determination of NAC from a pharmaceutical formulation obtained from a local pharmacy. [ABSTRACT FROM AUTHOR]