Research Article www.acsami.org
Electrolytically Exfoliated Graphene-Loaded Flame-Made Ni-Doped SnO2 Composite Film for Acetone Sensing Suparat Singkammo,† Anurat Wisitsoraat,‡ Chakrit Sriprachuabwong,‡ Adisorn Tuantranont,‡ Sukon Phanichphant,§ and Chaikarn Liewhiran*,†,§ †
Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50202, Thailand Nanoelectronics and MEMS Laboratory, National Electronics and Computer Technology Center, National Science and Technology Development Agency, Klong Luang, Pathumthani 12120, Thailand § Materials Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50202, Thailand ‡
ABSTRACT: In this work, flame-spray-made SnO2 nanoparticles are systematically studied by doping with 0.1−2 wt % nickel (Ni) and loading with 0.1−5 wt % electrolytically exfoliated graphene for acetone-sensing applications. The sensing films (∼12−18 μm in thickness) were prepared by a spin-coating technique on Au/Al2O3 substrates and evaluated for acetone-sensing performances at operating temperatures ranging from 150 to 350 °C in dry air. Characterizations by Xray diffraction, transmission/scanning electron microscopy, Brunauer−Emmett−Teller analysis, X-ray photoelectron spectroscopy and Raman spectroscopy demonstrated that Nidoped SnO2 nanostructures had a spheriodal morphology with a polycrystalline tetragonal SnO2 phase, and Ni was confirmed to form a solid solution with SnO2 lattice while graphene in the sensing film after annealing and testing still retained its high-quality nonoxidized form. Gas-sensing results showed that SnO2 sensing film with 0.1 wt % Ni-doping concentration exhibited an optimal response of 54.2 and a short response time of ∼13 s toward 200 ppm acetone at an optimal operating temperature of 350 °C. The additional loading of graphene at 5 wt % into 0.1 wt % Ni-doped SnO2 led to a drastic response enhancement to 169.7 with a very short response time of ∼5.4 s at 200 ppm acetone and 350 °C. The superior gas sensing performances of Ni-doped SnO2 nanoparticles loaded with graphene may be attributed to the large specific surface area of the composite structure, specifically the high interaction rate between acetone vapor and graphene−Ni-doped SnO2 nanoparticles interfaces and high electronic conductivity of graphene. Therefore, the 5 wt % graphene loaded 0.1 wt % Ni-doped SnO2 sensor is a promising candidate for fast, sensitive and selective detection of acetone. KEYWORDS: flame spray pyrolysis, acetone, SnO2, Ni-doping, graphene, gas sensor
1. INTRODUCTION
chromatography devices, which are normally only available in laboratories. VOC sensors on the basis of semiconductor metal oxide nanomaterials are promising alternatives for rapid estimation of VOCs in the field due to its low cost, high sensitivity and satisfactory selectivity. However, the performances of semiconductor gas sensors must be further improved to meet various requirements, particularly sensitivity and selectivity toward particular VOCs. Metal oxide semiconductors as gas-sensing materials have been widely for various types of gases due to their stable chemical transduction properties, which can reversibly convert chemical interactions on a surface to change the electrical conductivity.7−15 Particularly, tin dioxide (SnO2) is the bestunderstood and commercially used semiconducting metal oxide material due to numerous advantages including low cost, high
Volatile organic compounds (VOCs) are widely used active substances in various chemical-related industries. Due to their volatility and toxicity, they are becoming important environmentally hazardous pollutants that pose a serious threat to human health. VOCs the enter the human body through breathing will transport via the bloodstream to many organs and adversely affect brain, nervous, endocrine and skin systems, even at low concentrations.1−4 Acetone (C3H6O), a widely used VOC in industries and laboratories, is toxic to various organ systems and is a selective breath marker for type-1 diabetes.5 The acetone concentration in the breath of a healthy individual should be below 0.9 ppm and the concentration of more than 1.8 ppm could indicate ketosis (high ketone level in blood) of insulin-dependent diabetes. Thus, highly sensitive and selective sensors for acetone detection are required for the rapid assessment of diabetes and related diseases.5,6 Detections of VOCs at low concentrations have typically been conducted based on expensive analytical instruments such as gas © XXXX American Chemical Society
Received: October 6, 2014 Accepted: January 20, 2015
A
DOI: 10.1021/acsami.5b00161 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX
carbon microsphere template
powder impregnation to dichloromethane (DCH)
hydrothermal
FSP (powders) impregnation (composite) spin-coating (sensors)
Ni-doped SnO2 hollow spheres
3 wt % Ni-doped SnO2 thick film
Ni-doped SnO2 hollow nanofibers
SnO2/graphene nanocomposite
SnO2/graphene composite
SnO2 nanoparticles /reduced graphene oxide
SnO2/reduced graphene oxide composites
0−2 wt % Ni/SnO2 0.1 wt %Ni/SnO2 /0.1−5wt % graphene (G)
Lee et al.24
Cheng et al.25
Meng et al.28
Lin et al.29
Zhang et al.30
B
Chang et al.31
present work
hydrothermal
hydrothermal
wet chemical
electrospinning
hydrothermal
Liu et al.23
method
Ni-doped SnO2 hollow spheres
coprecipitation
Chen et al.22
sensing materials
SnO2 2 wt % Ni/SnO2 4 wt % Ce/SnO2 2 wt % Ni−4 wt % Ce codoped SnO2
Bagal et al.21
authors
acetone, 2.5−200 ppm ethanol, 2.5−200 ppm H2, CH4, 5−400 ppm H2S, 0.2−10 ppm NO2, 0.1−5 ppm 150−350 °C
ethanol 59−100 ppm 350 °C n-butanol ethanol 2−50 ppm 300 °C ethanol 0.1−0.8 ppm 350 °C acetone 2−1000 ppm 340 °C benzene, ethanol toluene, methanol chlorobenzene n-propanol 5−100 ppb 210 °C NH3 10−50 ppm 15−45 °C NO2 0.5−5 ppm 50 °C ethanol H2 S 0.56−1.68 ppm, 300 °C
acetone 0.2−500 ppm 300 °C
gas concentration
S = 22, 1.16 ppm S = 11, 1.16 ppm tres = 22 s, trec = 36 s selectivity = ethanol acetone, 200 ppm 0.1 wt % Ni/SnO2 S = 54.4, tres = 13 s, trec = 3 min 0.1 wt % Ni/SnO2/5 wt % G S = 169.7, tres = 5.4 s, trec = 2.5 min selectivity = acetone
S = 3.31, 5 ppm tres = 135 s, trec = 200 s
S = 15.9%, 50 ppm, 45 °C
