Mechanism for Alcohol Sensing Properties of p-Type AgNiO ₂ Nanoparticles: Adsorption Configuration and Charge-Transfer Effects

The chemiresistive properties of oxide materials are critical to their electrical performance, which originate from the interfacial phenomena involving gaseous species and the solid substrate, e.g., adsorption and charge-transfer processes. However, their fundamental mechanisms are still insufficiently understood. In this study, we investigated the sensing behavior of p-type delafossite AgNiO₂ nanoparticles to a series of gaseous alcohols based on the chemiresistive effect, which presented a trend that the response increases with the growing carbon chain from methanol to n-pentanol but decreases from n-hexanol to n-nonanol. Combining the first-principles calculations and experimental data, we proposed a novel mechanism to elucidate this phenomenon. The growing carbon chain may alter the adsorption configuration to facilitate the supplementary electron transfer routes, which eventually boosted the chemiresistive effect. However, further elongation of the carbon chain in an alcohol can bring about the steric hindrance effect, which, in turn, suppressed the charge transfer. These findings provided new insights into the fundamental design of the functional oxide materials for advanced electrical applications.