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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]

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]

The pyrolysis of metal-organic frameworks (MOFs) is an effective strategy for the synthesis of novel nanoporous structures for energy storage applications. In this work, the preparation of a zirconium oxide/carbon (ZrO 2 /C) nanocomposite via the pyrolysis of UiO-66 (a zirconium-based MOF) is reported for the first time. These MOF-derived metal oxide/carbon (ZrO 2 /C) materials have a great advantage in the case of supercapacitor applications over other MOFs or their derivatives as they do not need any external conductive agent. The ZrO 2 /C electrode exhibits an excellent electrochemical performance, delivering a specific capacitance of 241.5 F/g at 1 A/g current density. A 2 V symmetrical supercapacitor device is also prepared by employing a solid-state polymer gel electrolyte. The assembled device of ZrO 2 /C electrode has delivered a high energy density of around 29 Wh/kg (at a high power density of 1.5 kW/kg) while retaining almost 97% of the specific capacitance even after 2000 continuous charge/discharge cycles. • The development of efficient supercapacitor is a viable strategy to achieve energy storage devices. • Uniformly distributed oxides/carbon/oxide-carbon structures are prepared by the pyrolysis of MOF. • ZrO 2 /C composite is prepared via one-step pyrolysis of UiO-66 (zirconium-based MOF). • Superiority of a MOF-derived ZrO 2 /C composite is demonstrated in supercapacitor applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pencil peels is used to derive mixed phase activated carbon of high porosity and conductivity. • Asymmetrical supercapacitor is assembled using MOF derived Co 3 O 4 /WO 3 and Pencil derived activated carbon. • Asymmetrical Supercapacitor device retains long cycle life of 92.1 % after 5000 charge-discharge cycles. • The supercapacitor device shows high energy density of 50 Wh/kg at a power density of 90 W/kg. In this work, pencil peel is used to derive the mix phase activated carbon at different temperatures viz 700, 800, and 900 °C for hybrid supercapacitor applications. The derived carbon is showing the highest specific surface area for P-800 (Pencil peel@ 800 °C) sample and exhibits the graphitic and amorphous phase whose fraction can be controlled with pyrolysis temperature. Therefore, the as-prepared P-800 electrode shows the high specific capacitance of 553 F/g at a current density of 1 A/g. On the other hand, metal-organic framework (MOF) derived Cobalt-Tungsten oxide composites (Co 3 O 4 /WO 3) has been synthesized which shows a much higher specific capacitance value (544 F/g at 2 A/g) in the negative potential window. Therefore, an asymmetrical supercapacitor device has been assembled with P-800 as positive and Co 3 O 4 /WO 3 composites as a negative electrode in aqueous 1 M H 2 SO 4 (Sulfuric acid) electrolyte that delivers higher energy and power density in comparison to their symmetrical supercapacitor counterparts. [ABSTRACT FROM AUTHOR]

• Tetracyanoquinodimethane doped HKUST-1 has been explored as a battery type material. • A high specific capacity of 208.8 mAh/g (751 C/g) at 2 A/g has been achieved. • Solid-state symmetrical device has delivered high energy and power densities of 70.5 Wh/kg and 0.83 kW/kg respectively. • The energy storage device has yielded an energy efficiency of 58.6% and cyclic stability of 96%. Metal-organic frameworks (MOFs) are emerging as potential electrode materials for next-generation energy storage devices. Cu 3 (BTC) 2 (BTC = benzene tricarboxylate), also known as HKUST-1, is one of the most widely studied MOFs. In the present work, TCNQ (tetracyanoquinodimethane) doped HKUST-1, has been demonstrated as an efficient energy storage electrode material. The infiltration of TCNQ in HKUST-1 has resulted in the synthesis of a high surface area electrode material with significant electrical conductivity. TCNQ@HKUST-1 based electrode has delivered a high specific capacity of 208.8 mAh/g (751 C/g) at a current density of 2 A/g. An all-solid-state symmetrical device has been assembled using a polymer gel electrolyte, which has delivered energy and power densities of 70.5 Wh/kg and 0.83 kW/kg, respectively. Also, the device showed a maximum energy efficiency of 58.6% along with a long cycle life of 96% over 5000 successive charging-discharging cycles. The present system has yielded superior energy storage performance than most of the earlier reported MOF based electrodes. [Display omitted] [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are porous structures emerging as promising electrode materials due to their high structural diversity, controlled and wide pore network, and amenability to chemical modifications. COFs are solely composed of periodically arranged organic molecules, resulting in lightweight materials. Their inherent properties, such as extended surface area and diverse framework topologies, along with their high proclivity to chemical modification, have positioned COFs as sophisticated materials in the realm of electrochemical energy storage (EES). The modular structure of COFs facilitates the integration of key functions such as redox‐active moieties, fast charge diffusion channels, composite formation with conductive counterparts, and highly porous network for accommodating charged energy carriers, which can significantly enhance their electrochemical performance. However, ascribing intricate porosity and redox‐active functionalities to a single COF structure, while maintaining long‐term electrochemical stability, is challenging. Efforts to overcome these hurdles embrace strategies such as the implementation of reversible linkages for structural flexibility, stimuli‐responsive functionalities, and incorporating chemical groups to promote the formation of COF heterostructures. This review focuses on the recent progress of COFs in EES devices, such as batteries and supercapacitors, through a meticulous exploration of the latest strategies aimed at optimizing COFs as advanced electrodes in future EES technologies. [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]

Carbon paper has been synthesized by paper making process followed by composite formation, and further chemically oxidized by immersing into a mixture of sulphuric acid and potassium dichromate to be used as an electrode for supercapacitor applications. XRD and Raman spectra were used to analyze the structure, and the defects in the samples respectively, in due course of oxidation. FESEM images revealed the morphology of oxidized samples to be rougher, which contributes towards increased active sites for reaction. The sample (COCP‐60) optimized via electrochemical studies, was further tested in various electrolytes to study the electrode/electrolyte interaction. It delivered a highest areal capacitance of 6.02 F/cm2 (231.5 F/g) in acidic electrolyte at a current density of 5 mA/cm2 (0.19 A/g). This findings were further corroborated by surface and diffusion contribution studies wherein it was found that diffusion is more profound with acidic electrolyte. The supercapacitor device fabricated with COCP‐60 electrode delivered an energy density of 0.41 Wh/cm2 at 2.83 W/cm2 power density with coulombic efficiency of 98 %, and cyclic stability of ∼90 % for over 5000 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • State of the art information on core–shell MOF-based supercapacitors and batteries are explored. • CSMOF structures are discussed separately in terms of properties, synthesis and their types. • CSMOF structures for supercapacitors are compared in terms of specific capacitance, capacitance retention, energy density, and self-discharge. • CSMOF structures for batteries are compared in terms of reversible capacity, initial discharge capacity, and cyclic stability. • Besides Li-ion batteries, CSMOFs are also reviewed for Na-ion, K-ion, Li-S, Li-Se, and Li-O 2 batteries. • Critical assessment and future aspects are also explored for CSMOF based energy storage devices. Core-shell metal–organic framework (CSMOF) has attracted the attention of researchers in the material science and nanotechnology research field. The structural properties of CSMOF and their derived material include extortionate specific surface area and porosity, good structural flexibility, high stability, etc. These appealing properties make CSMOF a great alternative for various practical applications. CSMOF has shown great performance as an electrode material for energy storage applications. This review is primarily focused on the factor affecting the assemblies and synthesis of core shell structures, strategy to control the assemblies, synthesis methods, and properties of different CSMOFs for energy storage devices viz. supercapacitors (SC) and batteries. After that, different CSMOF structures are compared in terms of their performance parameters for SC including specific capacitance, capacitance retention, cyclic stability, energy density, and self-discharge.On the other hand, reversible capacity, initial discharge capacity, and cyclic stability are a few performance parameters for Li-ion batteries that are also discussed for different materials.CSMOF's applications for some other batteries like Na-ion, K-ion, Li-S, Li-Se, and Li-O 2 will likewise be discussed in other sections. Eventually, the expansion and future scope of CSMOF and its derivatives are proposed for upcoming energy storage applications. [ABSTRACT FROM AUTHOR]

Biowaste derived carbon materials are recently gaining attention owing to their high specific surface area (SSA) and decent electrical conductivity. Herein, pineapple peel derived porous carbon nanosheets have been synthesized at different activation temperatures (PP‐600, PP‐700 and PP‐800). This shows that its high SSA along with hierarchal pore size distribution makes it a suitable electrode material for supercapacitors. Further, the electrochemical performance of the as prepared electrode material was carried out in three different electrolytes viz. acidic (1 M H2SO4), basic (6 M KOH) and neutral (1 M Na2SO4) and among them 1 M H2SO4 electrolyte shows superior electrochemical performance. Furthermore, PP‐800 electrode material displayed highest specific capacitance of 368.8 F/g in 1 M H2SO4 electrolyte, which is much higher when tested and compared in 6 M KOH (34 F/g) and 1 M Na2SO4 (102.7 F/g) electrolytes at a constant current density of 1 A/g. Additionally, symmetrical solid‐state supercapacitor was fabricated by utilizing PP‐800 electrodes and PVA gel electrolyte, that rendered remarkable energy density of ∼43 Wh/kg at a high‐power density of ∼1 kW/kg. The as fabricated PP‐800//PP‐800 device displayed an extraordinary cycle life exhibiting capacitance retention of 83 % after 10000 ultra‐long charge‐discharge cycles. [ABSTRACT FROM AUTHOR]

Establishing green and reliable energy resources is very important to counteract the carbon footprints and negative impact of non-renewable energy resources. Metal-organic frameworks (MOFs) are a class of porous material finding numerous applications due to their exceptional qualities, such as high surface area, low density, superior structural flexibility, and stability. Recently, increased attention has been paid to surface mounted MOFs (SURMOFs), which is nothing but thin film of MOF, as a new category in nanotechnology having unique properties compared to bulk MOFs. With the advancement of material growth and synthesis technologies, the fine tunability of film thickness, consistency, size, and geometry with a wide range of MOF complexes is possible. In this review, we recapitulate various synthesis approaches of SURMOFs including epitaxial synthesis approach, direct solvothermal method, Langmuir-Blodgett LBL deposition, Inkjet printing technique and others and then correlated the synthesis-structure-property relationship in terms of energy storage and conversion applications. Further the critical assessment and current problems of SURMOFs have been briefly discussed to explore the future opportunities in SURMOFs for energy storage and conversion applications. [Display omitted] • State of the art information on SURMOF-based energy storage and conversion devices are explored. • SURMOFs are discussed separately in terms of need, preparation and their properties. • SURMOFs as an electrode for energy storage devices are explored in supercapacitors and batteries. • SURMOFs for energy conversion devices are explored in electrocatalysis and Solar cells applications. • Critical assessment and future aspects are also explored for SURMOF based energy storage and conversion devices. [ABSTRACT FROM AUTHOR]

Carbon-based materials generated from biowaste have recently attracted interest due to their exceptional surface and conductive properties. Cow dung derived porous carbon (CDPC) with a 3D structure and linked pores is synthesized in this study, making it an alternative electrode for supercapacitors (SC). Herein, we studied the diffusion and surface charge contribution and their relationship with the scan rate. Diffusion charge contribution is more prevalent at lower scan rates. Furthermore, a large fraction of surface charge contribution of 69.2 % at a high scan rate of 100 mV/s indicates rapid electrochemical kinetics and hence high-rate performance even at higher current densities. In addition, utilizing a 1 M H 2 SO 4 electrolyte, the CDPC electrode has attained a high specific capacitance value of 210 F/g at 0.5 A/g. Furthermore, symmetrical solid-state SC device displayed high energy density of 36 Wh/kg at good power density of 800 W/kg along with remarkable cyclic stability of 92.6 % after 10,000 charge-discharge cycles. Hence, these findings demonstrate that investigating surface and diffusion charge contributions opens up new avenues for tuning the supercapacitor performance. [Display omitted] • Waste cow dung derived carbon obtained by hydrothermal carbonization and activation • Surface and diffusion charge contribution studies are performed for CDPC electrode. • Solid-state symmetrical SC assembled using two CDPC electrodes and gel electrolyte • Device retains long cycle life of 92.6 % after 10,000 charge-discharge cycles. • Device delivers high energy density of 40 Wh/kg at a power density of 907 W/kg. [ABSTRACT FROM AUTHOR]