Mandal S, Rakibuddin M, Ananthakrishnan R. Strategic Synthesis of SiO
2-Modified Porous Co
3O
4 Nano-Octahedra Through the Nanocoordination Polymer Route for Enhanced and Selective Sensing of H
2 Gas over NO
x.
ACS OMEGA 2018;
3:648-661. [PMID:
31457921 PMCID:
PMC6641216 DOI:
10.1021/acsomega.7b01515]
[Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 01/02/2018] [Indexed: 06/10/2023]
Abstract
In this work, a strategic synthesis of Co3O4 nano-octahedra was developed through the facile nanoscale coordination polymer (NCP) route, which was further modified by SiO2 to be used as a sensor for enhanced sensing of hydrogen. The Co(II)-NCP-derived Co3O4 octahedra and SiO2-modified Co3O4 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 (H2TPR) techniques. The SiO2-modified Co3O4 sensor exhibited a stronger and selective electrical response to H2 gas over NO x at 225 °C than Co(II)-NCP-derived Co3O4 octahedra and the conventional Co3O4 powder. The composite sensor shows faster recovery and significant repeatability than the other two. The enhancement in the sensing performance of the SiO2-modified Co3O4 octahedron was explained by the effectiveness of surface modification, controlled morphology, and combination of synergistic effect of Co3O4 and SiO2. Surface engineering of the as-prepared Co3O4 nano-octahedra with an exposed (111) surface plane and later SiO2 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.
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