Strategic Synthesis of SiO(2)-Modified Porous Co(3)O(4) Nano-Octahedra Through the Nanocoordination Polymer Route for Enhanced and Selective Sensing of H(2) Gas over NO(x)

[Image: see text] In this work, a strategic synthesis of Co(3)O(4) nano-octahedra was developed through the facile nanoscale coordination polymer (NCP) route, which was further modified by SiO(2) to be used as a sensor for enhanced sensing of hydrogen. The Co(II)-NCP-derived Co(3)O(4) octahedra and SiO(2)-modified Co(3)O(4) octahedra were characterized using Fourier transform infrared, powder X-ray diffraction, Brunauer–Emmett–Teller, thermogravimetric analysis, field emission scanning electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature-programmed reduction (H(2)TPR) techniques. The SiO(2)-modified Co(3)O(4) sensor exhibited a stronger and selective electrical response to H(2) gas over NO(x) at 225 °C than Co(II)-NCP-derived Co(3)O(4) octahedra and the conventional Co(3)O(4) powder. The composite sensor shows faster recovery and significant repeatability than the other two. The enhancement in the sensing performance of the SiO(2)-modified Co(3)O(4) octahedron was explained by the effectiveness of surface modification, controlled morphology, and combination of synergistic effect of Co(3)O(4) and SiO(2). Surface engineering of the as-prepared Co(3)O(4) nano-octahedra with an exposed (111) surface plane and later SiO(2) modification facilitates effective gas adsorption, resulting in enhancement in sensing and selectivity over NO(x). The details of the synergistic effect and the plausible reasons for the improvement in gas-sensing parameters are discussed here. This study would offer new directions for development on the controlled synthesis of porous materials, in general, and in gas sorption or sensing, in particular.