Synthesis of Cu-doped V₂O₅ thin films with improved optical and CO₂ gas sensing

This study provides a comprehensive investigation of Cu-doped vanadium oxide (V₂O₅) thin films prepared via a sol-gel/spin-coating method, correlating dopant-induced structural and optical modifications with improved CO₂ sensing performance at room temperature. XRD confirmed the incorporation of Cu into the V₂O₅ lattice without secondary phase formation, while FE-SEM revealed a morphological transition from nanoplates to nanobelts upon Cu-doping. EDX verified uniform elemental distribution, and UV-Vis measurements indicated a reduced optical band gap, consistent with enhanced charge transport. FTIR spectra exhibited characteristic V-O vibrations, along with CO₂-related absorption bands, indicating favorable surface interactions. Gas sensing experiments demonstrated that Cu incorporation significantly improved sensitivity, response/recovery times, and selectivity. At 8880 ppm CO₂, the 10 at% Cu-doped V₂O₅ films achieved a response of 40.7% with fast response (3.83 min) and recovery (3.3 min) times, excellent repeatability, and stable operation over 30 days. These findings establish 10 at% Cu-doped V₂O₅ thin films as a promising, low-cost material for efficient room-temperature CO₂ detection.