Graphene oxide templating: facile synthesis of morphology engineered crumpled SnO2 nanofibers for superior chemiresistors

A new method of graphene oxide (GO) templating is pioneered to prepare highly porous oxide fibers consisting of crumpled two-dimensional (2D) SnO2 nanosheets (NSs). GO flakes, which are functionalized with Sn2+ ions through electrostatic interactions between negatively charged GO and positively charged Sn ions (Sn-loaded GO), are directly electrospun. During electrospinning, Sn-loaded GO flakes undergo self-crumpling on the as-spun polymeric nanofibers. After subsequent pyrolysis, highly porous oxide NFs comprised of crumpled SnO2 NSs are achieved, offering three distinct benefits, i.e., (i) a high surface area and broad pore size distribution stemming from the co-existence of 1D and 2D structures, (ii) formation and effective modulation of the electron depletion region due to the ultrasmall thickness of SnO2 NSs and small crystallite size, and (iii) the enhanced catalytic effect of Pt nanoparticles anchored on porous SnO2 NSs. As a result, under high humidity (95% RH), the Pt-functionalized SnO2 NS-assembled NFs exhibited an exceptionally high acetone response (R-air/R-gas = 79.4@1 ppm), excellent selectivity, fast response speed (approximate to 12.7 s), and outstanding stability at 350 degrees C. Sensor arrays were further utilized to discriminate simulated diabetic breath from healthy breath via pattern recognition, thus demonstrating potential feasibility for reliable sensing of breath biomarkers.