Wet Chemistry Methods for Synthesizing High-Entropy Nanoparticles: A Review of the Synthesis Strategies and Various Applications

High-entropy nanoparticles (HE-NPs) have recently gained considerable attention owing to their potential to yield several materials with unique characteristics due to the homogeneous mixing of five or more elements. The complexity of HE-NPs leads to electronic hybridization, lattice distortion, and sluggish diffusion effects, all of which contribute to their performance and stability. The formation of HE-NPs is thermodynamically limited, particularly by enthalpic factors. To overcome these limitations and design intricate nanostructures, wet chemistry can be employed as a relatively straightforward synthesis method. This review provides an overview of HE-NPs, including their definition, thermodynamic principles, and wet-chemical synthesis methods. It further explores the diverse range of applications of HE-NPs and examines how specific nanoparticle morphologies and compositions can be tailored efficiently using various synthesis strategies. Additionally, this review discusses case studies presenting optimized HE-NPs for individual applications, demonstrating their high performance. By identifying the key factors that contribute to their superior performance, this review offers valuable insights into future research directions for HE-NPs.