Controlled synthesis of electrospun hollow Pt-loaded SnO2 microbelts for acetone sensing

Challenges for ubiquitous diffusion of gas analytes into semiconducting metal oxides (SMOs) based sensing layers have necessitated the introduction of unprecedented synthesis techniques for thin, porous and high-performance gas sensing materials. In this work, electrospinning and calcination were employed to prepare unprecedented SiO2-SnO2 core-shell microbelts (hereinafter referred to as SiO2@SnO2 BLs) followed by etching away of SiO2 in NaOH solution (pH 12) to achieve hollow SnO2 BLs (hereinafter referred to as SnO2 HBLs) with mean crystal size of 14.01 nm, large BET surface area (143.5 m2g-1), high porosity (mean pore size of 5.7 nm), and shell thickness of 58.3 +/- 11.4 nm. Sensitization of SnO2 HBLs with apoferritin-templated platinum nanoparticles (Pt NPs) enhanced their detection capability toward acetone. Response (defined as Ra/Rg, where Ra and Rg are sensor resistances in air and target gas, respectively) of Pt(0.12 %)_SnO2 HBLs toward 2 ppm acetone was up to 7.8 times higher compared to that of pristine SnO2 HBLs, and exhibited faster response (9.2 s). The Pt(0.12 %)_SnO2 HBLs based sensor indicated a promising long-term stability, and outstanding repeatability of response (Ra/Rg = 93.7 +/- 0.89) toward 25 cycles of 2 ppm acetone exposure in a humid environment of 90 % relative humidity. This performance could be attributed to the unique morphology of HBLs, sensitization effects of catalytic Pt NPs, and enlargement of the electron-depleted layer resulting from a Schottky barrier between Pt NPs and SnO2 grains.