SnO2/NiO composite thin films for formaldehyde detection

Formaldehyde (HCHO) is a volatile organic compound that outgasses from textiles and composite wood products, with adverse health effects resulting from prolonged exposure to concentrations of ~10 ppb in air. Commercially available HCHO sensors struggle to detect HCHO at such low concentrations. Tin dioxide (SnO₂) / nickel oxide (NiO) poly crystalline composite films have shown sensitivity to ~ 100 ppb via resistance measurements. Here we explore several thin Snθ2/NiO films produced by pulsed laser deposition (PLD), varying preparation parameters including NiO loading and substrate temperature during deposition. These variables are shown to affect both composition and morphology, as characterized by XPS, XRD, SEM, and SEM-EDX. Here we report the response time and sensitivity of these sensor materials to HCHO concentrations from ~10 ppb to 1000 ppb at various operating temperatures.