Nanostructured high-entropy oxides for catalysis: linking entropy to function.

High entropy oxides (HEOs) are gaining rapid attention due to densely distributed active centers, tunable surface areas, robust lattices, flexible geometries and self-balanced electronic states. These features give them activity and durability that single- or binary-metal oxides rarely match in thermal, electro- and photo- catalysis. We systematically examine four entropy-driven effects, namely high-entropy stabilization, severe lattice distortion, sluggish diffusion and cocktail-like multi-element synergy, all of which govern phase formation, defect chemistry and functional performance. By simultaneously optimizing the surface area, lattice robustness and scalable processing, we outline how porous architectures, low-temperature integrity, phase control and high-throughput manufacturing are merged into a single framework. Complex disordered structures of HEOs challenge traditional characterization, demanding advanced methods. In situ vibrational spectroscopy, operando X-ray characterization, DFT and artificial-intelligence converge to resolve the dynamic structure-property relationships that underpin HEO catalysis. We hope this review sparks wider interest in high-entropy oxides and accelerates their path from laboratory curiosity to industrial catalysts.