With the rapid improvement of the global economy, the role of energy has become even more vital in the 21st century. In this regard, energy storage/conversion devices have become a major, worldwide research focus. In response to this, we have prepared two-dimensional (2D)-hierarchical sheet-like ZnCo₂O₄ microstructures for supercapacitor applications using a simple hydrothermal method. The 2D-hierarchical sheet-like morphologies with large surface area and smaller thickness enhanced the contact area of active material with the electrolyte, which increased the utilization rate. We investigated the electrochemical performance of sheet-like ZnCo₂O₄ microstructures while using Cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD), and Electrochemical impedance spectroscopy (EIS) analysis. The electrochemical results demonstrated that the ZnCo₂O₄ electrode possesses 16.13 mF cm⁻² of areal capacitance at 10 µA cm⁻² of current density and outstanding cycling performance (170% of capacitance is retained after 1000 cycles at 500 µA cm⁻²). The high areal capacitance and outstanding cycling performance due to the unique sheet-like morphology of the ZnCo₂O₄ electrode makes it an excellent candidate for supercapacitor applications.

One of the hugely focused areas of research for addressing the world’s energy and environmental challenges is electrochemical water oxidation. Morphological modulation of nanomaterials is essential for producing efficient electrocatalysts to achieve the required results. The purpose can be achieved by controlling synthesis parameters, and this is a key factor which greatly influences the oxygen evolution reaction (OER) performance during electrochemical water splitting. In this study, synthesis of cobalt molybdate (CoMoO₄) through a simple and low-cost hydrothermal/solvothermal strategy with tunable morphology is demonstrated. Different morphologies, namely rods-like, buds-like, and sheets-like, referred to as R-CMO, B-CMO, and S-CMO, respectively, have been obtained by systematically varying the solvent media. Their catalytic activity towards OER was investigated in 1.0 M aqueous KOH medium. R-CMO nanoparticles synthesized in an aqueous medium demonstrated the lowest overpotential value of 349 mV to achieve a current density of 10 mA cm⁻² compared with other as-prepared catalysts. In contrast, the B-CMO and S-CMO exhibited overpotential values of 369 mV and 384 mV, respectively. Furthermore, R-CMO demonstrated an exceptional electrochemical stability for up to 12 h.

Developing low-cost, highly active, and stable electrocatalysts is essential to realize various renewable energy storage and conversion systems. In particular, zeolite imidazole frameworks (ZIFs) and ZIF-based composites have garnered considerable interest for energy-related applications. In this study, ZIF-8@CoFe₂O₄ composites are synthesized using a simple and facile method. Three ZIF-8@CoFe₂O₄ composites named ZCFO-1, ZCFO-2, and ZCFO-3, synthesized with varying concentrations of CoFe₂O₄ (10, 20, and 40.0 mg, respectively), are used. The synthesized ZCFO-composites are used as catalysts in the electrocatalytic methanol oxidation reaction (MOR) and oxygen evolution reaction (OER). In the MOR, the ZCFO-1 electrocatalyst exhibits a higher current density and stability for more than 6 h than other electrocatalysts. In addition, the synthesized electrocatalysts are tested for the OER, and ZCFO-1 exhibits a lower overpotential of 330 mV and a Tafel slope of 84 mV dec⁻¹. The synthesized ZCFO-1 electrocatalyst exhibits higher activity and stability for both the MOR and OER, thus suggesting that it is an alternative to noble metal electrocatalysts.

Nanoflakes-like MnMoO ₄ synthesized using CTAB as a structure-directing agent via a facile hydrothermal method with high phase purity, high surface area and superior electrochemical characteristics for high-performance asymmetric supercapacitors.