Exceptional enhancement of response and stability in ethanol sensors based on Pr-doped In2O3

Utilizing a one-step hydrothermal synthesis, this study produced Pr-doped In 2 O 3 -based ethanol gas sensors. The material’s elemental composition and morphology were investigated by XPS, XRD, SEM, and other characterization methods. Effective substitution of In 3 + lattice sites by Pr 3+ /Pr 4+ ions was achieved, generating smooth irregular polyhedral particles composed of interlocked octahedra with varying sizes. At the optimum temperature of 300 °C, the sensor exhibited a response of 179–100 ppm ethanol, accompanied by rapid response/recovery times of 43 s and 13 s. Compared to pure In₂O₃, the response value increased by 10 times, and the recovery time was reduced by 66 s, while exhibiting excellent selectivity and long-term stability (>150 days). The enhanced ethanol response stems from increased adsorbed oxygen density, which creates a more polarized initial high-resistance state for subsequent gas-sensing reactions by forming a more pronounced surface electron depletion layer and higher initial barrier. Upon contact with target gases, the higher density of adsorbed oxygen participates as reaction sites and promotes surface redox reactions. This leads to a greater flux of released captured electrons, triggering a sharp decrease in the surface barrier and a dramatic macroscopic resistance transition in the material. Ultimately, this significantly amplifies the sensor's response magnitude. The work concludes by presenting a detailed mechanistic analysis of the sensing behavior.