The gas-sensing of SmCoOX/MOX (M=Fe, Zn, In, Sn) having a heterojunction

Eco-friendly approach towards green synthesis of zinc oxide nanocrystals and its potential applications

“…Among various metal nanoparticles, zinc oxide nanocrystals (ZnO) exhibit unique characteristics such as semiconducting (Sangeetha et al 2011), piezoelectric (Fujihara et al 2001), and pyroelectric properties (Vayssieres et al 2001), for transparent electronics (Vanathi et al 2014), spin electronics (Wang 2004), and coating (Waham et al 2010), as ultraviolet (UV) light emitters (Akiyama et al 1998), chemical sensors (Mochinaga et al 1998), and catalysts (Elseviers and Verelst 1999), and in space applications (Singh et al 2011). Several chemical and physical methods are employed to obtain ZnO nanocrystals, but these are generally not environmentally friendly and lead to health concerns.…”

Hydrogen sensitivity of doped CuO/ZnO heterocontact sensors

“…Nakamura et al studied CO adsorption on CuO in an attempt to decrease the catalytic activity of the surface in order to form stable CO adsorbates on CuO so that these CO molecules can react with the oxygen adsorbed on ZnO instead of reacting with the adsorbed oxygen on CuO surface [8]. In addition to the CuO/ZnO system, many other different heterocontact systems, both p-n and n-n, have been studied for gas detection [9][10][11][12][13][14]. Among these systems La 2 CuO 4 /ZnO p-n heterocontact showed strong rectifying characteristics and high sensitivity towards hydrogen gas [9].…”

The effect of relative humidity on the NO2 sensitivity of a SnO2/WO3 heterojunction gas sensor

“…Heterojunction gas sensors were first reported in 1979 in the context of humidity measurement [7] and, since this initial study, the responses of several heterojunction sensor systems to target gases including CO, H 2 , H 2 O, NO 2 and C 2 H 5 OH have been investigated [8][9][10][11][12][13][14][15][16]. Several heterojunction sensor systems have been reported, mostly based on interfaces between p-type (p) and n-type (n) semiconducting ceramics [11][12][13][14], although heterojunction sensors formed between two n-type semiconducting ceramics, giving rise to an n-N interface have also been described [15,16].…”

“…Several heterojunction sensor systems have been reported, mostly based on interfaces between p-type (p) and n-type (n) semiconducting ceramics [11][12][13][14], although heterojunction sensors formed between two n-type semiconducting ceramics, giving rise to an n-N interface have also been described [15,16]. In these studies, it has been established that the sensing mechanism is based on a modification, due to the adsorption of gases, of the structure and hence the current flow characteristics of the heterointerface [10].…”