Room-temperature gas sensors have aroused great attention in current gas sensor technology because of deemed demand of cheap, low power consumption and portable sensors for rapidly growing Internet of things applications. As an important approach, light illumination has been exploited for room-temperature operation with improving gas sensor’s attributes including sensitivity, speed and selectivity. This review provides an overview of the utilization of photoactivated nanomaterials in gas sensing field. First, recent advances in gas sensing of some exciting different nanostructures and hybrids of metal oxide semiconductors under light illumination are highlighted. Later, excellent gas sensing performance of emerging two-dimensional materials-based sensors under light illumination is discussed in details with proposed gas sensing mechanism. Originated impressive features from the interaction of photons with sensing materials are elucidated in the context of modulating sensing characteristics. Finally, the review concludes with key and constructive insights into current and future perspectives in the light-activated nanomaterials for optoelectronic gas sensor applications.

Three-dimensional (3D) hierarchically porous nanostructures with controlled morphology and dimensionality represent one kind of important material and have received enormous attention for a series of applications. In this work, 3D hierarchically porous ZnO architectures were synthesized via an amino acid-assisted biomimetic hydrothermal method combined with subsequent calcination. First a basic zinc carbonate (BZC) precursor with a lamellar spherical morphology assembled by interconnected nanosheets was synthesized. By subsequent calcination, the as-obtained BZC precursor can be facilely transformed into porous ZnO with a large surface area of 193.7 m²/g, while maintaining its 3D hierarchical morphology. The 3D hierarchically porous ZnO superstructures are further employed as a support to load Au nanoparticles (AuNPs) to construct hybrid nanomaterials for chemical gas sensors. The AuNP-functionalized 3D hierarchically porous ZnO nanomaterials, combining the high surface accessibility of porous materials and catalytic activity of small AuNPs, demonstrated excellent sensor properties in terms of higher sensitivity and very fast response. Furthermore, it is expected this AuNP-functionalized 3D hierarchically porous nanostructure may provide a new pathway to develop advanced nanomaterials for applications like gas sensors, low temperature CO oxidation and photocatalysis.