High-Performance 3D Nanostructured Silver Electrode for Micro-Supercapacitor Application

In the current energy crisis scenario, the development of renewable energy forms such as energy storage systems among the supercapacitors is an urgent need as a tool for environmental protection against increasing pollution. In this work, we have designed a novel 3D nanostructured silver electrode through an antireplica/replica template-assisted procedure. The chemical surface and electrochemical properties of this novel 3D electrode have been studied in a 5 M KOH electrolyte. Microstructural characterization and compositional analysis were studied by SEM, energy-dispersive X-ray spectroscopy, XRD technique, and Kripton adsorption at -198 °C, together with cyclic voltammetry and galvanostatic charge-discharge cycling measurements, Coulombic efficiency, cycle stability, and their leakage current drops, in addition to the self-discharge and electrochromoactive behavior, were performed to fully characterize the 3D nanostructured electrode. Large areal capacitance value of 0.5 F/cm2 and Coulombic efficiency of 97.5% are obtained at a current density of 6.4 mA/cm2 for a voltage window of 1.2 V (between -0.5 and 0.8 V). The 3D nanostructured silver electrode exhibits excellent capacitance retention (95%) during more than 2600 cycles, indicating a good cyclic stability. Additionally, the electrode delivers a high energy density of around 385.87 μWh/cm2 and a power density value of 3.82 μW/cm2 and also displays an electrochromoactive behavior. These experimental results strongly support that this versatile combined fabrication procedure is a suitable strategy for improving the electrochemical performances of 3D nanostructured silver electrodes for applications as micro-supercapacitors or in electrochemical devices.

Noble metal-based materials in high-performance supercapacitors

This review comprehensively summarizes and evaluates the recent progress in the research of noble metals and their composite electrode materials for supercapacitors.

Scalable Synthesis of Ag Networks with Optimized Sub-monolayer Au-Pd Nanoparticle Covering for Highly Enhanced SERS Detection and Catalysis

Highly porous tri-metallic Ag_xAu_yPd_z networks with a sub-monolayer bimetallic Au-Pd nanoparticle coating were synthesized via a designed galvanic replacement reaction of Ag nanosponges suspended in mixed solutions of HAuCl₄ and K₂PdCl₄. The resulting networks’ ligaments have a rough surface with bimetallic nanoparticles and nanopores due to removal of Ag. The surface morphology and composition are adjustable by the temperature and mixed solutions’ concentration. Very low combined Au and Pd atomic percentage (1−x) where x is atomic percentage of Ag leads to sub-monolayer nanoparticle coverings allowing a large number of active boundaries, nanopores, and metal-metal interfaces to be accessible. Optimization of the Au/Pd atomic ratio y/z obtains large surface-enhanced Raman scattering detection sensitivity (at y/z = 5.06) and a higher catalytic activity (at y/z = 3.55) toward reduction reactions as benchmarked with 4-nitrophenol than for most bimetallic catalysts. Subsequent optimization of x (at fixed y/z) further increases the catalytic activity to obtain a superior tri-metallic catalyst, which is mainly attributed to the synergy of several aspects including the large porosity, increased surface roughness, accessible interfaces, and hydrogen absorption capacity of nanosized Pd. This work provides a new concept for scalable synthesis and performance optimization of tri-metallic nanostructures.

Co3O4 nanocrystals derived from a zeolitic imidazolate framework on Ni foam as high-performance supercapacitor electrode material

A binder-free method was adopted to obtain a Ni foam/Co₃O₄ electrode.