Doping and Nanostructuring of Spinel Ferrites for Enhanced Gas Sensing: Recent Developments

ABSTRACT

Spinel ferrites have emerged as promising materials for gas sensing due to their tunable electronic properties, magnetic characteristics, and thermal stability. This review examines recent developments in doping and nanostructuring strategies for enhancing their gas sensing performance. Strategic incorporation of transition‐metal dopants (Fe ³⁺ , Co ²⁺ , Ni ²⁺ , Mn ²⁺ , and Zn ²⁺ ) enables precise control over oxygen‐vacancy concentration, electronic conductivity, and surface reactivity through defect‐chemistry manipulation, while nanostructuring approaches, including hierarchical architectures, hollow spheres, core‐shell configurations, and one‐dimensional structures, substantially increase surface‐to‐volume ratio and gas‐diffusion kinetics. Sensing mechanisms are analyzed through band‐structure engineering, surface catalysis, and charge‐transfer processes, supported by operando characterization that provides direct mechanistic insight. Reported performance gains include sub‐ppb detection limits, response times reduced to seconds, and markedly enhanced selectivity relative to undoped bulk materials, with synthesis‐structure–property relationships established to guide rational design. Persistent challenges include reproducible large‐scale synthesis, long‐term stability, cross‐sensitivity mitigation, and cost‐effective production. Future directions encompass machine‐learning‐guided materials discovery, quantum‐sensing phenomena, bio‐inspired recognition mechanisms, and sustainable synthesis routes, supported by advanced characterization and multi‐scale computational modeling. Convergence with artificial intelligence, IoT platforms, and green chemistry positions doped, nanostructured spinel ferrites to address critical applications in environmental monitoring, industrial safety, healthcare diagnostics, and emerging smart sensing systems.