Exploring the promise of one-dimensional nanostructures: A review of hydrogen gas sensors

Among different materials that have been used for hydrogen sensing, one-dimensional (1D) nanostructures have shown promising results due to their enhanced specific surface area, nanoporosity and improved surface characteristics (in particular, uniformity and stability) facilitate high number of active sites. This paper aims to comprehensively review 1D nanostructure-based hydrogen sensors from three different aspects including: (1) Synthesis techniques: briefly overview the four primary synthesis techniques and how the critical processing parameters affect the morphology and sensing behavior, (2) Materials: properly distinguish the sensing mechanisms and properties of inorganic materials such as metal oxide semiconductors (MOS) combined/doped with organic carbon-based materials and polymers, and how the heterostructures can improve the sensing performance, and (3) Enhancement schemes such as additive functionalisation, material composition and light-assisted approaches to further elevate sensing characteristics. Future challenges are yet to be investigated in this area, which is discussed in this review to enlighten the way for future explorations.