Phosphorus-doped porous perovskite LaFe1-xPxO3-δ nanosheets with rich surface oxygen vacancies for ppb level acetone sensing at low temperature

Perovskite-type oxide semiconductors (ABO3) with defective conduction properties have been regarded as highly promising gas-sensitive materials due to their abundant structural types. However, pure ABO3 gas sensors usually have suboptimal sensing response due to low specific surface area and few adsorption sites. Recently, surface oxygen vacancies (Ov) defects have been shown to be a remarkably effective way to enhance the sensing response of gas sensors by increasing the number of adsorption sites and changing the energy level structure. In view of the above, herein, P-doped perovskite LaFe1-xPxO3-δ (x = 0.005, 0.01, 0.03, 0.05) with abundant Ov defects were prepared by sol–gel method and fabricated as sensors for the acetone detection. Characterization and test results show that LaFe0.99P0.01O3-δ with porous nanosheet structure has excellent acetone gas-sensitive performance. Compared to pure LaFeO3 gas sensor, the optimal operating temperature of LaFe0.99P0.01O3-δ is reduced to 180 °C and response value is improved nearly twofold, whose limit of detection is even at the ppb level. Crucially, the results of electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) verify that the sensing characteristics of the LaFe1-xPxO3-δ sensor are strongly correlated with the Ov defect. In addition, further theoretical analysis shows that P doping in LaFeO3 induces Ov defects and modulates frontier electron orbital energy levels of the material, thus increasing the chemisorbed oxygen species and enhancing the intermolecular interactions. In this work, the vital function of Ov defects in perovskite-type gas sensors is highlighted, which also provides an effective and feasible way to improve the performance of gas sensors.