Abstract
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.