Gas sensitivity enhancement in praseodymium-doped cobalt ferrite nanoparticles: investigating humidity effects and palladium synergy

The objective of this research is to explore the influence of praseodymium incorporation into cobalt ferrite nanoparticles, derived from sol-gel, on their response to hydrogen gas. Additionally, we investigated the hydroxyl scavenging capacity of praseodymium ions by comparing the results obtained at low relative humidity (RH ~ 20%) and high relative humidity (RH ~ 50%). Our findings revealed that the optimal gas sensing properties of the CoFe_2 − xPr_xO₄ semiconductor (where x = 0, 0.02, 0.04, 0.06) were achieved with a Pr concentration of 0.02 at a working temperature of 300 °C. Scanning electron microscopy and mapping Energy-dispersive X-ray spectroscopy (EDS) analysis of Pr-doped CoFe₂O₄ nanoparticles provided evidence for the existence of a secondary phase at higher Pr concentrations, which impacted gas-sensing performance when x > 0.02. Furthermore, the addition of palladium proved to be effective in enhancing the moisture-resistant gas-sensing properties of the CoFe_1.98Pr_0.02O₄ gas sensor. The synergistic interaction between palladium and praseodymium ions was responsible for the observed enhanced anti-humidity and hydrogen gas detection characteristics.