Noble Metal‐Decorated Nanostructured Zinc Oxide: Strategies to Advance Chemiresistive Hydrogen Gas Sensing

Abstract

Hydrogen (H2) is known as the key player in the alternative and renewable energy revolution and henceforth H2 production, transportation, storage and usage have been a major interest of current research. However, due to severe safety concerns, strategies are indispensable to devise superior H2 sensors, particularly selective and sensitive H2 sensors. In this personal account, three specific gas sensing constructs; zinc oxide (ZnO) nanostructures‐, noble metal nanoparticles‐decorated ZnO‐ and noble metal nanoparticles‐decorated ZnO nanostructures on reduced graphene oxide (rGO)‐based H2 sensors have been demonstrated. The dynamic response and H2 sensing characteristics of ZnO nanostructures‐based H2 sensors were found to be improved compared to those of pristine ZnO. High‐resolution field emission scanning electron microscopy (FESEM) confirmed the flower‐like nanostructures that had higher surface area around the nanoscale petals. The mechanism behind the superior sensing characteristics of ZnO nanostructures‐based H2 sensor has been demonstrated. Decoration of ZnO nanostructures with noble metal nanoparticles, particularly platinum (Pt) and gold (Au) was observed to be useful in achieving better H2 sensing performance compared to that of ZnO nanostructures. The Pt‐ and Au‐decorated ZnO nanostructures followed the well‐known “Spill‐over” mechanism in enhancing the H2 sensing characteristics. Abundant free electrons/holes generation and higher conductivity are two important parameters for designing selective and sensitive gas sensors. In this context, a hybrid nanocomposite, rGO−ZnO has been developed and decorated with noble metal nanoparticles, particularly Pt and Au. The ultimate sensing material has been characterized and compared to those of pristine ZnO, ZnO nanostructures and Pt‐ and Au‐decorated ZnO for H2 gas sensing applications. Such systemic and focus strategies is critical not only for developing efficient H2 gas sensors but also for better understanding the mechanisms underlying such superior performance.

Critical Sensing Modalities for Hydrogen: Technical Needs and Status of the Field to Support a Changing Energy Landscape

“…Efforts to lower MOS operating temperatures without sacrificing sensitivity have focused on increasing surface-to-volume ratios. MOS microcubes, thin films and nanostructures such as nanoparticles, , nanospheres, , nanorods, nanowires, nanotubes, nanofilms, and nanoflowers, − all exhibit improved sensitivity at lower temperature. In addition, functionalizing the MOS surface with metals like Pd, Pt, or Ni nanoparticles greatly improves H 2 sensitivity.…”

Metal Oxide-Based Sensors for Ecological Monitoring: Progress and Perspectives

“…For instance, investigations into the morphology effect of SnO 2 and ZnO on sensitivity have demonstrated that nanobelts significantly outdo the other types of 1D nanostructures. Herewith, sensors based on ZnO are the most attractive due to their low cost, ease of preparation, and thermal/chemical stability [35,36].…”

Advances in Noble Metal-Decorated Metal Oxide Nanomaterials for Chemiresistive Gas Sensors: Overview

“…Actually, several reviews about noble metal-decorated SMOs-based gas sensors are focused more on either certain type of noble metals, such as Ag-modified SMOs-based gas sensors [ 35 ] and Pd-decorated nanostructures-based gas sensors [ 36 ], or certain type of SMOs, such as noble metal-decorated nanostructured ZnO-based H 2 gas sensors [ 37 ]. However, few comprehensive reviews focusing on the recent advances in diverse noble metal-decorated SMOs for high-performance gas sensors have been reported.…”