The influence of rhodium on SnO2-CO gas sensor

Ultrasensitive detection of trimethylamine using Rh-doped SnO2 hollow spheres prepared by ultrasonic spray pyrolysis

“…The R a values of the Rh-SnO 2 hollow spheres were significantly higher than those of the pure SnO 2 hollow spheres. This is consistent with the literature to show the two to three orders of magnitude increase in R a by loading Rh to Pd-SnO 2 [28] and In 2 O 3 thick film sensors [25], indicating the acceptor role of Rh. The R a value of the Rh-SnO 2 hollow spheres was highest (2.4 × 10 8 ) at 325 • C to show the maximum TMA response (Fig.…”

“…This is similar to the increase of S MAX and the decrease of T MAX by loading Pt catalysts to SnO 2 sensor in the literature [35,36], indicating the catalytic role of Rh to promote gas sensing reaction at the lower sensor temperature. The doping of Rh is known to enhance the responses to C 2 H 5 OH, CO, and CH 4 in SnO 2 sensors [28,37,38] and the response to C 2 H 5 OH in In 2 O 3 sensors [25]. Silva et al [39] analyzed the reaction mechanism of the partial oxidation of ethanol on Rh/CeO 2 catalysts by using diffuse reflectance infrared spectroscopy (DRIFTS).…”

XPS study of the SnO2 films modified with Rh

“…According to our estimations, 1.0 ML corresponded to the averaged thickness of the rhodium coverage ~ 0.3 nm . However, numerous studies have shown that such coatings are not optimal for many applications, including catalysis and gas sensorics . The optimum characteristics of the sensors and catalysts were obtained at much lower rhodium concentrations on the surface of the metal oxides.…”

“…14,16 However, numerous studies have shown that such coatings are not optimal for many applications, including catalysis 17 and gas sensorics. 10,[18][19][20] The optimum characteristics of the sensors and catalysts were obtained at much lower rhodium concentrations on the surface of the metal oxides. For example, Shimizu et al 19 believe that the optimum gas sensitivity effect was achieved at the rhodium concentration of 0.1 wt%.…”

Effect of additives on the response of sensors utilizing semiconducting oxide on carbon monoxide sensitivity

“…A degree of selectivity could be conferred by careful control of sensor operating temperature and use of specific additives. In several cases researchers have modified the sensor composition with additives such as Sb, 1 Pt/Pd, 2-5 Rh, 6 in an attempt to improve CO sensitivity, lower the operating temperature and irradicate cross sensitivity to other reducing gases. Several investigators have also carried out experiments of the selective detection of CO in air, by the addition of metal oxides to the base material SnO 2 such as Sb 2 O 3 , 7,8 Al 2 O 3 , 9,10 Bi 2 O 3 , [11][12][13][14][15] ThO 2 .…”