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

Abstract

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 (∼12.7 s), and outstanding stability at 350 °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.