Oxygen vacancy engineering in (FeMnNiCoCr)₃O₄-modified GaN for room-temperature ammonia sensing

In this work, a composite of GaN with (FeMnNiCoCr) 3 O 4 was designed, and a chemiresistive gas sensor based on this composite material was constructed for NH 3 detection at room temperature. The (FeMnNiCoCr) 3 O 4 modification caused the collapse of GaN morphology and formed a more porous nanostructure, promoting the gas diffusion and adsorption process. The inherent high configurational entropy and lattice adaptation capabilities of (FeMnNiCoCr) 3 O 4 effectively address the deficiency of O V in GaN intrinsic defects through entropy-driven interfacial stabilization and dynamic lattice matching mechanisms. The fabricated gas sensor exhibited improved sensitivity, lower detection limit (100 ppb), fast response/recovery (19/66 s) and good stability compared with pure GaN at room temperature. This work provides a novel strategy for oxygen vacancy regulation and an alternative scheme for the development of ppb-level NH 3 sensors.