Facile engineering of metal–organic framework derived SnO2@NiO core–shell nanocomposites based gas sensor toward superior VOCs sensing performance

Aiming to achieve high-sensitivity volatile organic compounds (VOCs), it is of great significance to continuously enhance the sensing performance of metal oxide based sensors. Herein, novel NiO nanoplates-decorated on SnO 2 nanofibers 1D core–shell structures derived from metal-organic frameworks (MOFs) are fabricated by the facial solvothermal method and heat treatment for VOCs gas sensors. The morphology and composition of 1D core shell SnO 2 @NiO are regulated by solvothermal time in the range of 0 ∼ 24 h. Based on the unique structure and composition of SnO 2 @NiO, SnO 2 @NiO with 4 h solvothermal time (denoted as SnO 2 @NiO-4) exhibits excellent selectivity, high response (R a /R g  = 25.6) and low detection limit as well as good response linearity between response and concentration of xylene. Especially, the obtained SnO 2 @NiO-8 and SnO 2 @NiO-16 show the high sensitivity to acetone (R a /R g  = 28.7) and triethylamine (R a /R g  = 13.7), respectively. Structural characterizations such as SEM, TEM, and Mott-Schottky results demonstrate the core–shell structure with p-n heterojunction. In-depth investigations on reaction mechanism reveal XPS, photoluminescence (PL), and ESR testing reveal the intrinsic defects such of oxygen vacancy and Ni 3+ active sites. And in situ FTIR, online mass spectroscopy, as well as UV/UPS analysis further discover the evolution of intermediates and products during the surface catalysis reaction. These results demonstrate that the remarkable sensing performance of SnO 2 @NiO-8 can be attributed to several factors, including abundant oxygen vacancy, formation of p-n heterostructure and efficient Ni 3+ /Ni 2+ catalyzing, which beneficial for increased active sites and enhanced electron transport. This synthetic strategy provides an effective method for the facile engineering of high-performances metal oxide-based sensors towards practical health assessment.