Tailoring CO₂ gas sensing properties of V₂O₅ through polyaniline incorporation: A structural and optical study

PANI–V₂O₅ nanocomposites with varying polyaniline (PANI) content (1–9 wt.%) were synthesized via a sol–gel method followed by mechanical mixing to investigate their structural, optical and gas sensing properties. X-ray diffraction confirmed the orthorhombic V₂O₅ phase with no impurity formation, while peak broadening and Williamson–Hall analysis revealed reduced crystallite size and increased microstrain with increasing PANI content, indicating strong interfacial interaction. FTIR spectroscopy verified the coexistence of characteristic vibrational modes of both PANI and V₂O₅, confirming successful composite formation. UV–Vis absorption studies and Tauc analysis showed a systematic reduction in optical band gap due to enhanced charge delocalization. Particle size analysis indicated nanoscale dimensions with improved dispersion at intermediate PANI loadings. Gas sensing studies demonstrated that the 7 wt.% PANI–V₂O₅ nanocomposite exhibited superior CO₂ sensing performance, attributed to optimized p–n heterojunction formation, enhanced surface activity, and efficient charge transfer. These findings highlight the potential of PANI–V₂O₅ nanocomposites for gas sensing applications.