A General Strategy for Bandgap Engineering Via Anion‐Lattice Doping in High‐Entropy Oxides

Abstract Bandgap engineering is a critical tool for tailoring the electronic properties of functional materials, traditionally achieved by modifying the cation sublattice. Here, a generalizable strategy is introduced that leverages facile anion‐lattice doping in high entropy materials to modulate the bandgap in high‐entropy metal oxides (HEMOs). By incorporating nitrogen into a single‐phase high‐entropy metal oxide/nitride (HEMO:HEMN) solid solution, a substantial bandgap reduction is achieved from 3.55 eV (HEMO) to ≈2.46 eV (HEMO:HEMN), significantly enhancing electronic conductivity. Unlike conventional bandgap tuning approaches that rely on cation substitution or heterojunction formation, this method exploits anion‐mediated entropy stabilization, enabling uniform bandgap narrowing across the entire solid solution. This anion‐lattice engineering strategy is broadly applicable to high‐entropy systems, providing a new pathway for designing energy materials with tailored electronic properties. The resulting HEMO:HEMN solid solution exhibits a tenfold increase in capacitance and capacity compared to HEMO in supercapacitor and lithium‐ion battery tests, demonstrating the transformative potential of anion‐driven bandgap modulation for next‐generation energy storage and conversion technologies.