Precisely tailored LaFeO3 dendrites using urea and piperazine hexahydrate for the highly selective and sensitive detection of trace level acetone

Abstract

Trace level sensing of chemical vapours using metal oxides with fascinating morphologies has attracted much attention in many fields. Leaf-like dendrites have been investigated as a potential morphology for sensors because of their fast surface reactivity and transducer–receptor function. However, the preparation and understanding of these unique and homogenized morphological metal oxides are still far from sufficient. Herein, simple additives urea (9 mM) and piperazine hexahydrate (0–21 mM, 3 mM increments) were used to tailor homogenized lanthanum ferrite (LaFeO₃) dendrites under hydrothermal conditions. The sequential reactions revealed that the urea by-products NH₄⁺ and CO₃²⁻ controlled the formation of the La₂O₃/Fe₂O₃ impurity phases and improved the formation of LaFeO₃. The protonated piperazine molecules reacted with the metal hydroxides to form a bridge-like La–2O–Fe structure between two protonated piperazine molecules. This complex structure induced the growth of dendrites and led to the formation of LaFeO₃ dendrites upon calcination. By utilizing these LaFeO₃ dendrites for trace level detection at low temperature, an acetone sensing device was fabricated, which experimentally achieved the detection range from 10 ppm to 10 ppb with excellent stability and low noise to signal ratio at a chamber and device temperature of 100 °C. The maximum and minimum sensitivity values were 157.88 and 1.05, respectively. The sensitivity, response and recovery time for 1 ppm acetone were 37.63, 1.19 s and 95.81 s, respectively, and the device exhibited outstanding repeatability with long term stability. Furthermore, the selective detection of acetone in the presence of comparable sensitive molecules ethanol and formaldehyde was achieved by varying the chamber and device temperatures.