Insight into Au functionalization on core-shell LaFeO3 spheres for high-response and selectivity n-butanol gas sensors with DFT study

In this work, LaFeO3 core-shell spheres functionalized with different amounts of Au nanoparticles (NPs) were successfully synthesized through a facile hydrothermal method. Various characterization methods were conducted to confirm the morphology, microstructure, and surface properties of the samples. The results demonstrated that the morphology of Au-LaFeO3 has a uniform core-shell structure. Besides, gas sensing investigation indicated that compared with pure LaFeO3, gas sensors based on 4 wt. % Au-LaFeO3 core-shell spheres exhibited remarkably enhanced sensing properties (5 times higher) toward n-butanol. The sensor has a response value of 115 for 100 ppm n-butanol at 225 °C and has a low limit of detection (500 ppb, 1.2). The enhancement can be mainly ascribed to the Schottky barrier between Au NPs and LaFeO3. The possible adsorption configuration, the adsorption energy and charge transfer amount of the adsorbate in the absence or presence of Au NPs are calculated based on the first principles. n-Butanol has the highest adsorption energy and is easier to adsorb than other gases. n-Butanol loses more electrons after the functionalization of Au NPs which become negative charge centers and have a spillover effect. This work also provided a new candidate sensing material for high-performance n-butanol sensors.