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

Abstract

• O v defect-rich phosphorus-doped porous perovskite LaFeO 3-δ nanosheets were prepared. • Characterizations and DFT results indicate that doping with P induces O v defects. • Perovskite LaFe 1-x P x O 3-δ sensor has excellent acetone sensing properties at 180 °C. • O v defects reconfigure electron distribution and promote gas adsorption. Perovskite-type oxide semiconductors (ABO 3 ) with defective conduction properties have been regarded as highly promising gas-sensitive materials due to their abundant structural types. However, pure ABO 3 gas sensors usually have suboptimal sensing response due to low specific surface area and few adsorption sites. Recently, surface oxygen vacancies (O v ) 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 LaFe 1-x P x O 3-δ (x = 0.005, 0.01, 0.03, 0.05) with abundant O v defects were prepared by sol–gel method and fabricated as sensors for the acetone detection. Characterization and test results show that LaFe 0.99 P 0.01 O 3-δ with porous nanosheet structure has excellent acetone gas-sensitive performance. Compared to pure LaFeO 3 gas sensor, the optimal operating temperature of LaFe 0.99 P 0.01 O 3-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 LaFe 1-x P x O 3-δ sensor are strongly correlated with the O v defect. In addition, further theoretical analysis shows that P doping in LaFeO 3 induces O v 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 O v defects in perovskite-type gas sensors is highlighted, which also provides an effective and feasible way to improve the performance of gas sensors.