Development of High Performance Hydrogen Sensor Using Metal Functionalized ZnO/Reduced Graphene Oxide Nanocomposite Synthesized via High Power Laser

Hydrogen (H2) is a clean, renewable, and efficient energy source, with the potential to become a solution for clean energy generation. However, its use as an alternative energy source is associated with numerous safety issues requiring fast, and accurate leakage detection. Chemiresistors, resistive gas-sensing elements that change their electrical conductivity/resistivity in the presence of an analyte, are extensively used in the private as well as the industrial sectors. Nanostructured zinc oxide (ZnO) is a functional material that is sensitive to flammable, and toxic gases. However, ZnO sensors are usually working at high temperature and are suffering from poor selectivity. Decoration of ZnO sensor with noble metal catalysts (Pt, Pd, and Au) is a well-known strategy to reduce its operating temperature and improve its response due to their superior H2 solubility at room temperature. However, such sensors are still suffering from cross-sensitivity issues with other gases. Recently, graphene and reduced graphene oxide (rGO) have attracted great interest in sensing applications due to their unique electrical, and structural properties. As a chemical sensing material, rGO has many advantages over graphene and GO including, reactive sites and high electron mobility at room temperature. rGO can be fabricated in large quantity with low cost using different chemical methods to provide enough active sites for further chemical modification with other nanostructured materials. The reduction of GO to graphene and hence fabrication of rGO can be carried out by using chemical-reducing agents such as hydrazine, and sodium borohydride. However, these chemical-reducing agents are highly toxic and potentially explosive chemical, and therefore its use should be avoided in the fabrication of rGO. As a consequence, many researchers endeavour to develop green and effective methods for fabrication of rGO with desirable properties for diverse sensing applications. As an extension of these endeavours, this proposed project aims to develop a green and effective method for fabrication of ZnO/rGO nanocomposite-based high performance hydrogen sensor. To achieve this aim, three main procedures should be implemented: (1) development of a method to fabricate nanostructured ZnO (nanoparticles, nanowires, naorods)/rGO nanocomposite using high power laser without using any hazardous agent. (2) characterization of the fabricated sensors using different techniques. 3. evaluation of the gas sensing properties (response, selectivity, response/recovery time, stability) towards low level of H2. This proposal will also focus on the effect of coating ZnO/rGO nanocmposite with noble metals on the sensing performance. Last but not least, this project will contribute to the education of undergraduate and graduate students by offering them an opportunity to get involved in developing state-of- art nanostructured gas sensors.