Perovskite Nanoparticle-Sensitized Ga₂O₃ Nanorod Arrays for CO Detection at High Temperature

Noble metal nanoparticles are extensively used for sensitizing metal oxide chemical sensors through the catalytic spillover mechanism. However, due to earth-scarcity and high cost of noble metals, finding replacements presents a great economic benefit. Besides, high temperature and harsh environment sensor applications demand material stability under conditions approaching thermal and chemical stability limits of noble metals. In this study, we employed thermally stable perovskite-type La_0.8Sr_0.2FeO₃ (LSFO) nanoparticle surface decoration on Ga₂O₃ nanorod array gas sensors and discovered an order of magnitude enhanced sensitivity to carbon monoxide at 500°C. The LSFO nanoparticle catalysts was of comparable performance to that achieved by Pt nanoparticles, with a much lower weight loading than Pt. Detailed electron microscopy and X-ray photoelectron spectroscopy studies suggested the LSFO nanoparticle sensitization effect is attributed to a spillover-like effect associated with the gas-LSFO-Ga₂O₃ triple-interfaces that spread the negatively charged surface oxygen ions from LSFO nanoparticles surfaces over to β-Ga₂O₃ nanorod surfaces with faster surface CO oxidation reactions.