Growth of Graphitic Carbon Nitride-Incorporated ZnO Nanorods on Silicon Pyramidal Substrates for Enhanced Hydrogen Sensing Applications

Abstract

Monitoring the hydrogen gas (H₂) level is highly important in a wide range of applications. Oxide-carbon hybrids have emerged as a promising material for the fabrication of gas sensors for this purpose. Here, for the first time, graphitic carbon nitride (g-C₃N₄)-doped zinc oxide nanorods (ZNRs) have been grown on silicon (Si) pyramid-shaped surfaces by the facile hydrothermal reaction method. The systematic material analyses have revealed that the g-C₃N₄ nanostructures (NS) have been consistently incorporated into the ZNRs on the pyramidal silicon (Py-Si) surface (g-C₃N₄-ZNRs/Py-Si). The combined properties of the present structure exhibit an excellent sensitivity (∼53%) under H₂ gas exposure, better than that of bare ZNRs (12%). The results revealed that the fine incorporation of g-C₃N₄ into ZNRs on the Py-Si surface improves the H₂ gas sensing properties when compared to that of the planar silicon (Pl-Si) surface. The doping of g-C₃N₄ into ZNRs increases the electrical conductivity through its graphene-like edges (due to the formation of delocalized bonds in g-C₃N₄ during carbon self-doping), as revealed by FESEM images. In addition, the presence of defects in g-C₃N₄ induces the gas adsorption properties of ZnO through its active sites. Moreover, the integration of the 1D structure (g-C₃N₄-ZNRs) into a 3D pyramidal structure opens up new opportunities for low-cost H₂ gas sensing at room temperature. It is an easy way to enhance the gas sensing properties of ZNRs at room temperature, which is desirable for practical H₂ sensor applications.

Keywords: 1D/3D structure; ZnO nanorods on pyramidal Si; g-C3N4-ZNRs hybrids; g-C3N4-ZNRs hydrogen sensors; g-C3N4-ZNRs on Si pyramids.