Chitosan-templated nanocatalysts on one-dimensional metal oxide for chemical sensor

Abstract

In this work, we introduce chitosan-Pt complex (CS-Pt) as an effective template for catalytic Pt sensitiza-tion and creation of abundant mesopores in $SnO_2$ nanofibers (NFs). The Pt particles encapsulated by the CS exhibit ultra-small size (~ 2.6 nm) and high dispersion characteristics due to the repulsion between the CS. By combining CS-Pt with electrospinning, mesoporous $SnO_2$ NFs uniformly functionalized with Pt catalyst (CS-Pt@$SnO_2$ NFs) are synthesized. Particularly, the mesopores with diameters of ~20 nm are increased through the decomposition of the CS, while small $SnO_2$ grain size (~ 14.3 nm) are maintained by the pinning effect of the CS. Consequently, CS-Pt@$SnO_2$ NFs exhibited outstanding response ($R_{air}/R_{gas}$ = 141.92 at 5 ppm), ex-tremely low detection limit ($R_{air}/R_{gas}$ = 2.9 at 5 ppb), excellent selectivity, long-term stability, and fast response (12 s)/recovery (44 s) speed toward 1 ppm acetone at $350^\cir C$ and high humidity (90% RH). Furthermore, the sensor array of CS-Pt@$SnO_2$ NFs, CS driven $SnO_2$ NFs, polyol-Pt loaded $SnO_2$ NFs, and dense $SnO_2$ NFs, suc-cessfully classified the exhaled breath of simulated diabetics and healthy subjects by using pattern recogni-tion system. These results clearly demonstrate that the mesoporous oxide NFs, particularly functionalized by CS-metal complex catalysts, open up new class of sensing layers with high sensitivity and selectivity.