Recent advancements in zero, one, two, and three-dimensional transition metal nitride-based supercapacitor electrodes

The development of next-generation energy storage devices that are economical, industry-scalable, and environment-sustainable is urgently required to ensure a steady and reliable supply of renewable energy for widespread utilization in powering diverse devices. Among the various explored energy storage systems, supercapacitors (SCs) have significant advantages ascribed to their longer cycle lifetime, superior power density, and quick charging-discharging capabilities compared to conventional batteries and electrostatic capacitors. Despite these advantages, SC's low energy density prevents them from being extensively deployed and thus presents enormous potential for future research and development of high energy density SCs. The strategic design of the SC's electrode is essential for addressing their inherent limitation of low energy density. In this aspect, strategically engineered transition metal nitrides (TMNs) based electrodes have been extensively researched and utilized for SCs to provide improved energy density, higher power density, and extended cycle life owing to their excellent pseudocapacitive properties. In this review article, we have summarized the recently achieved advances in zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) TMNs-based nanostructured electrodes for high-performance SC applications. The 0D (quantum dots, nanoparticles, nanospheres), 1D (nanowires, nanorods, nanotubes), 2D (nanosheets, nanoplates), and 3D (nanopyramids, nanoflowers, honeycomb nanostructures) TMNs based nanostructured electrodes, and their unique electrochemical properties have been discussed in detail. The review not only categorizes TMNs-based electrodes but also critically addresses the correlation of nanostructure morphology with electrochemical functionality, elucidating their intrinsic charge storage mechanism, ion diffusion kinetics, and conductivity optimization strategies. Dimensional engineering highlights how quantum confinement in 0D materials, electron transport pathways in 1D nanostructures, interlayer ion diffusion kinetic in 2D materials, and interconnected porous networks in 3D nanostructures are contributing to pushing the limits of energy density, power density, rate capability, and cyclability. Finally, the latest developments in TMNs for SC applications are thoroughly analyzed in this study, which additionally examines the current challenges and proposes future research avenues for improving their electrochemical performance.