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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]

Several in-situ electrochemical approaches have been developed for performing a localized photoelectrochemical investigation of the photoanode. One of the techniques is scanning electrochemical microscopy (SECM), which probes local heterogeneous reaction kinetics and fluxes of generated species. In traditional SECM analysis of photocatalysts, evaluation of the influence of radiation on the rate of studied reaction requires an additional dark background experiment. Here, using SECM and an inverted optical microscope, we demonstrate the determination of O2 flux caused by light-driven photoelectrocatalytic water splitting. Photocatalytic signal and dark background are recorded in a single SECM image. We used an indium tin oxide electrode modified with hematite (α-Fe2O3) by electrodeposition as a model sample. The light-driven flux of oxygen is calculated by analysis of SECM image recorded in substrate generation/tip collection mode. In photoelectrochemistry, the qualitative and quantitative knowledge of oxygen evolution will open new doors for understanding the local effects of dopants and hole scavengers in a straightforward and conventional manner. [ABSTRACT FROM AUTHOR]