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In this work, zeolitic imidazolate frameworks (ZIF‐8@ZIF‐67)‐based core–shell structure as a supercapacitor electrode is synthesized. The core–shell structure is designed with a ZIF‐8 core, onto which a ZIF‐67 shell is grown. This unique architecture aims to expedite the diffusion of electrolyte ions, facilitate inner–outer metal ion electron transfer, and consequently enhance electrochemical performance. When used as an active electrode material, the material delivers 263.43 F g−1 of capacitance at 0.5 A g−1 of discharge rate. The core–shell structure exhibits 68% of surface contribution toward the total capacitance. At the scan rate of 50 mV s−1, the sample almost exhibits equal contribution of diffusion and surface charge contribution. Further an asymmetric supercapacitor (ASC) device is assembled, featuring a ZIF‐8@ZIF‐67 core–shell metal‐organic framework (MOF) as a positive electrode and waste‐tissue‐paper‐derived activated carbon as negative electrode using 1 m H2SO4 aqueous electrolyte. The ASC device delivers an energy density of 38.4 Wh kg−1 at the power density of 0.8 kW kg−1, along with long cycle life of 95.2% after an extensive 10 000 cycles. In this work, the significance of the ZIF‐based core–shell structure in advancing supercapacitor technology, which further can be extended to multiple core–shell structure and other MOF combination, is highlighted. [ABSTRACT FROM AUTHOR]

In this study, nanosized zeolitic imidazolate framework‐8 (ZIF‐8) crystal has been produced on the universitetet i oslo‐66 (UiO‐66) metal–organic framework (MOF) to make core–shell structure using a layer‐by‐layer deposition method. In comparison to the pristine UiO‐66 and ZIF‐8, the core–shell MOF exhibits superior performance in terms of specific capacitance. This enhanced performance is attributed to its remarkable ability to facilitate the rapid diffusion of electrolyte ions through nanosized ZIF‐8 and enhance the electron transfer process involving the inner and outer metal ions within the UiO‐66@ZIF‐8 structure. Remarkably, the core–shell structure achieves an impressive specific capacitance of 588.8 F g−1 at a current density of 0.5 A g−1 using 1 m sulfuric acid (H2SO4) aqueous electrolyte. Additionally, the UiO‐66@ZIF‐8 core–shell material is demonstrated as a positive electrode, coupled with activated carbon (AC) derived from waste tissue paper serving as the negative electrode, in the fabrication of an asymmetric supercapacitor (ASC) device. At a power density of 400 W kg−1, this assembled asymmetric device delivers a notably high energy density of 53 Wh kg−1 along with a cyclic stability of 94.8% after 10 000 cycles. This study substantiates the superior performance of the UiO‐66@ZIF‐8 core–shell MOF structure as a highly effective supercapacitor electrode material, surpassing the performance of its pristine MOF counterparts. [ABSTRACT FROM AUTHOR]

Microbial electrosynthesis (MES) presents a versatile approach for efficiently converting carbon dioxide (CO2) into valuable products. However, poor electron uptake by the microorganisms from the cathode severely limits the performance of MES. In this study, a graphitic carbon nitride (g-C3N4)-metal–organic framework (MOF) i.e. HKUST-1 composite was newly designed and synthesized as the cathode catalyst for MES operations. The physiochemical analysis such as X-ray diffraction, scanning electron microscopy (SEM), and X-ray fluorescence spectroscopy showed the successful synthesis of g-C3N4-HKUST-1, whereas electrochemical assessments revealed its enhanced kinetics for redox reactions. The g-C3N4-HKUST-1 composite displayed excellent biocompatibility to develop electroactive biohybrid catalyst for CO2 reduction. The MES with g-C3N4-HKUST-1 biohybrid demonstrated an excellent current uptake of 1.7 mA/cm2, which was noted higher as compared to the MES using g-C3N4 biohybrid (1.1 mA/cm2). Both the MESs could convert CO2 into acetic and isobutyric acid with a significantly higher yield of 0.46 g/L.d and 0.14 g/L.d respectively in MES with g-C3N4-HKUST-1 biohybrid and 0.27 g/L.d and 0.06 g/L.d, respectively in MES with g-C3N4 biohybrid. The findings of this study suggest that g-C3N4-HKUST-1 is a highly efficient catalytic material for biocathodes in MESs to significantly enhance the CO2 conversion. [ABSTRACT FROM AUTHOR]

In the context of emerging electric devices, the demand for advanced energy storage materials has intensified. These materials must encompass both surface and diffusion-driven charge storage mechanisms. While diffusion-driven reactions offer high capacitance by utilizing the bulk of the material, their effectiveness diminishes at higher discharge rates. Conversely, surface-controlled reactions provide rapid charge/discharge rates and high power density. To strike a balance between these attributes, we devised a tri-composite material, TiO2/Carbon/MoS2 (T10/MoS2). This innovative design features a highly porous carbon core for efficient diffusion and redox-active MoS2 nanosheets on the surface. Leveraging these characteristics, the T10/MoS2 composite exhibited impressive specific capacitance (436 F/g at 5 mV/s), with a significant contribution from the diffusion-controlled process (82%). Furthermore, our symmetrical device achieved a notable energy density of ~ 50 Wh/kg at a power density of 1.3 kW/kg. This concept holds promise for extending the approach to other Metal–Organic Framework (MOF) structures, enabling enhanced diffusion-controlled processes in energy storage applications. [ABSTRACT FROM AUTHOR]

L-cysteine conjugated molybdenum disulphide (MoS2) nanosheets have been covalently attached to a gold coated surface plasmon resonance (SPR) optical fiber to prepare a robust and stable sensor. Owing to the multifunctionality of the deposited nanosheet conjugate, the antibodies are also covalently conjugated in the subsequent step to realize the design of a SPR optical fiber biosensor for the two important bioanalytes namely, Ferritin and Immunoglobin G (IgG). The different stages of the biosensor preparation have been characterized and verified with microscopic and spectroscopic techniques. A uniform and stable deposition of the L-cysteine/MoS2 nanosheets has allowed the biosensor to be reused for multiple times. Unlike the peeling-off of the MoS2 coatings from the gold layer reported previously in the case of physically adsorbed nanomaterial, the herein adopted strategy addresses this critical concern. It has also been possible to use the single SPR fiber for both Ferritin and IgG bioassay experiments by regenerating the sensor and immobilizing two different antibodies in separate steps. For ferritin, the biosensor has delivered a linear sensor response (SPR wavelength shifts) in the concentration range of 50–400 ng/mL, while IgG has been successfully sensed from 50 to 250 µg/mL. The limit of detection for Ferritin and IgG analysis have been estimated to be 12 ng/mL and 7.2 µg/mL, respectively. The biosensors have also been verified for their specificity for the targeted molecule only. A uniform and stable deposition of the nanomaterial conjugate, reproducibility, regeneration capacity, a good sensitivity, and the specificity can be highlighted as some of key features of the L-cysteine/MoS2 optical fiber biosensor. The system can be advocated as a useful biosensor setup for the sensitive biosensing of Ferritin and IgG. [ABSTRACT FROM AUTHOR]

Abstract: Photoelectrochemical splitting of water using 170 MeV Au13+ irradiated (fluence: 1012 and 1013 ions cm−2) hematite (α-Fe2O3) thin film has been attempted. Enhanced photocurrent values were observed upon irradiation at fluence 1012 ions cm−2. However, at fluence 1013 ions cm−2 marginal decrease in the photocurrent was observed due to probable collapse of the initially formed tubular structures, resulting in the formation of large number of discontinuities/dislocations, which act as recombination centers for photogenerated charge carriers. The X-ray diffraction analysis exhibited diffused nature, indicating highly disordered material at 1013 ions cm−2. It also confirmed the inhomogeneous strain field distribution upon irradiation. Elastic recoil detection analysis exhibited no change occurring in stoichiometry of thin films throughout irradiation. Atomic force microscopy at fluence of 1012 ions cm−2 indicated formation of tubular. The band gap energy of these films has been found in the range of 2.01–2.08 eV, as determined by optical measurements. [Copyright &y& Elsevier]