ZnO Nanoparticles/Reduced Graphene Oxide Bilayer Thin Films for Improved NH3-Sensing Performances at Room Temperature

Abstract

ZnO nanoparticles and graphene oxide (GO) thin film were deposited on gold interdigital electrodes (IDEs) in sequence via simple spraying process, which was further restored to ZnO/reduced graphene oxide (rGO) bilayer thin film by the thermal reduction treatment and employed for ammonia (NH3) detection at room temperature. rGO was identified by UV-vis absorption spectra and X-ray photoelectron spectroscope (XPS) analyses, and the adhesion between ZnO nanoparticles and rGO nanosheets might also be formed. The NH3-sensing performances of pure rGO film and ZnO/rGO bilayer films with different sprayed GO amounts were compared. The results showed that ZnO/rGO film sensors exhibited enhanced response properties, and the optimal GO amount of 1.5 ml was achieved. Furthermore, the optimal ZnO/rGO film sensor showed an excellent reversibility and fast response/recovery rate within the detection range of 10–50 ppm. Meanwhile, the sensor also displayed good repeatability and selectivity to NH3. However, the interference of water molecules on the prepared sensor is non-ignorable; some techniques should be researched to eliminate the effect of moisture in the further work. The remarkably enhanced NH3-sensing characteristics were speculated to be attributed to both the supporting role of ZnO nanoparticles film and accumulation heterojunction at the interface between ZnO and rGO. Thus, the proposed ZnO/rGO bilayer thin film sensor might give a promise for high-performance NH3-sensing applications.

Advances in designs and mechanisms of semiconducting metal oxide nanostructures for high-precision gas sensors operated at room temperature

“…Among these carbon materials, the composites of reduced graphene oxide (rGO) and SMONs are the most investigated ones for gas sensor applications. rGO has been used to combine with various types of SMONs for enhancing the gas sensing properties, and these SMONs include Fe 2 O 3 , 315 In 2 O 3 , 316 ZnO, 317,318 The RT NO 2 sensor fabricated using rGO/a-Fe 2 O 3 126 exhibits a response value of 3.86 to 5 ppm NO 2 , which is better than that of pure rGO, whose response is 1.38. In addition, it has significantly shorter response/recovery times of 32/1432 s, compared with those of the sensors made of pure rGO (2059 s, 40130 s).…”

Metal Oxide Gas Sensors by Nanostructures

“…Graphene-ZnO 17.4 (100 ppm) 1.25 (10 ppm) 23.5 (1 ppm) [36][37][38] Graphene-SnO 2 2.45 (20 ppm) 1.9 (500 ppm) 9 (400 ppm) [39][40][41] Graphene-TiO 2 -1.7 (10 ppm) 6.5 (100 ppm) [42,43] MWCNT-ZnO 1.025 (10 ppm) 41 (10 ppm) - [44,45] MWCNT-SnO 2 2 (10 ppm) 1.06 (60 ppm) 0 (100 ppm) [39,46,47] MWCNT-TiO 2 -2 (100 ppm) 7 (50 ppm) [48,49] SWCNT-ZnO 6 (250 ppm) -0 (50 ppm) [50,51] SWCNT-SnO 2 11.1 (10 ppm) 50 (100 ppm) 1.29 (50 ppm) [52][53][54] SWCNT-TiO 2 ---- Table 1.…”

Graphene-enhanced metal oxide gas sensors at room temperature: a review

“…Tai et al [ 46 ] deposited ZnO nanoparticles and GO thin films on gold interdigital electrodes (IDEs) through a simple spray process and thermally reduced the deposits to ZnO–rGO composites. The ZnO–rGO sensor exhibited a response of 1.2 to NH 3 with ultra-fast response/recovery times of 78 s/188 s, which was much better than that of a pure rGO sensor (low response and endless recovery time).…”