Sensing properties of MWCNTs layers electrodecorated with metal nanoparticles for detection of aromatic hydrocarbon comp
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Sensing properties of MWCNTs layers electrodecorated with metal nanoparticles for detection of aromatic hydrocarbon compounds E. Dilonardo1,2*, M. Alvisi3, R. Rossi3, G. Cassano,3 F. Di Palo,4 G. Palazzo,2 M. Penza3 1 Department of Chemistry, Università degli Studi di Bari Aldo Moro, Bari, Italy. 2 Department of Electrotechnics and Electronics (DEE), Politecnico di Bari, Bari, Italy. 3 ENEA, - Brindisi Research Center, Brindisi, Italy 4 Arpa Puglia, Bari, Italy. *Corresponding authors: Elena Dilonardo ([email protected]). ABSTRACT An electrophoretic process is proposed to deposit electrochemically-preformed Au or Pd NPs, with controlled size, directly on MWCNTs-based chemiresistors to improve the detection of aromatic pollutants, compared to pristine ones. The sensing properties of pristine and functionalized MWCNTs were evaluated at an operating temperature of 40°C towards various concentrations of one aromatic pollutant, belonging to the dangerous BTEX class of compounds, m-Xylene. The sensing performance was related to the metal used in the functionalization process. Metal-doped MWCNTs sensors exhibited a very high gas sensitivity to m-Xylene even at low (80 ppb) concentration at low operating temperature (40°C), good reversibility and repeatability, with the sensing properties controlled by the type of deposited metal catalyst. The results indicate that Metal-modified MWCNT-based chemiresistive gas sensors has good potential in practical applications, due to its remarkable performance, low power consumption, and facile synthesized methods. INTRODUCTION Chronic exposition to a specific harmful class of indoor compounds, composed of benzene, toluene, ethyl benzene and xylene (BTEX), negatively impacts on the environment and, specifically, on the human health, causing skin and sensory irritation, carcinogenesis, mutagenesis, central nervous system depression and respiratory system damage [1]. Therefore, the rapid detection of these compounds is desired to maintain their concentration within permissible limit and avoid exposure associated health hazards. To date, different techniques are applied for BTEX monitoring, despite of their high cost, and. in many cases, large volume, complexity or non-selectivity due to the lack of alternative methods. The necessity to detect and monitor these molecules put a pressing need for development of fast responsive BTEX detection systems. Beside different approaches developed to detect BTEX [2, 3], chemiresistive sensors have distinct advantages of cost, response time and possibility of an easy integration into a chemiresistive array. Since the electrical conductivity is an essential requirement for the development of chemiresistive sensors, MWCNTs are promising as sensing layer in chemiresistors, thanks to their intrinsic sensing characteristics, such as the high conductivity. As a result, there is an increasing interest in the development of MWCNTs-based gas sensors with fast response time, high sensitivity, selectivity, portability and low-power consumption. Beside the p
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