Synergistically Driven CoCr-LDH@VNiS2 as a Bifunctional Electrocatalyst for Overall Water Splitting and Flexible Supercapacitors

Utilizing alternative energy sources to fossil fuels has remained a significant issue for humanity. In this context, efficient earth-abundant bifunctional catalysts for water splitting and energy storage technologies like hybrid supercapacitors have become essential for achieving a sustainable future. Herein, CoCr-LDH@VNiS₂ was synthesized by hydrothermal synthesis. The CoCr-LDH@VNiS₂ catalyst entails 1.62 V cell voltage to reach the current density of 10 mA cm^-2 for overall water splitting. The CoCr-LDH@VNiS₂ electrode illustrates a high electrochemical specific capacitance (Csp) of 1380.9 F g^-1 at a current density of 0.2 A g^-1 and an outstanding stability with 94.76% retention. Moreover, the flexible asymmetric supercapacitor (ASC) achieved an energy density of 96.03 W h kg^-1@0.2 A g^-1 at a power density of 539.98 W kg^-1 with remarkable cyclic stability. The findings provide a new approach toward the rational design and synthesis of bifunctional catalysts for water splitting and energy storage.

Beyond Pristine Metal-Organic Frameworks: Preparation of Hollow MOFs and Their Composites for Catalysis, Sensing, and Adsorption Removal Applications

Metal-organic frameworks (MOFs) have been broadly applied to numerous domains with a substantial surface area, tunable pore size, and multiple unsaturated metal sites. Recently, hollow MOFs have greatly attracted the scientific community due to their internal cavities and gradient pore structures. Hollow MOFs have a higher tunability, faster mass-transfer rates, and more accessible active sites when compared to traditional, solid MOFs. Hollow MOFs are also considered to be candidates for some functional material carriers. For example, composite materials such as hollow MOFs and metal nanoparticles, metal oxides, and enzymes have been prepared. These composite materials integrate the characteristics of hollow MOFs with functional materials and are broadly used in many aspects. This review describes the preparation strategies of hollow MOFs and their composites as well as their applications in organic catalysis, electrochemical sensing, and adsorption separation. Finally, we hope that this review provides meaningful knowledge about hollow-MOF composites and their derivatives and offers many valuable references to develop hollow-MOF-based applied materials.