In this research, two pellets of titanium dioxide TiO₂ were prepared at room temperature. The first was pure titanium dioxide, and the other was doped with silver (2.5%). The pellets were deposited on porous silicon (PSi) with the pulsed laser deposition (PLD) technique. The results of scanning electron microscopy and energy-dispersive X-ray spectroscopy showed improvements in the surface morphologies of the TiO₂/PSi and TiO₂@Ag/PSi composites. The composites were then tested as CO₂ gas sensors. The electrical measurements of the composites showed a decrease in the electrical resistance of the CO₂ gas sensor doped with a metal. Sensitivity to CO₂ increased to up to 55% in Ag-doped TiO₂ film with a concentration of 2.5%, and the highest sensitivity value was obtained in the pure titanium dioxide film (26%).