Abstract
Highly sensitive gas sensing materials are of great importance for environmental pollution monitoring. In this study, four nanohybrid materials containing different phenoxyl substituents of cobalt phthalocyanines (tetra-β-carboxylphenoxylphthalocyanine cobalt (cpoPcCo), tetra-β-(4-carboxy-3-methoxyphenoxy)phthalocyanine cobalt (cmpoPcCo), tetra-β-phenoxylphthalocyanine cobalt (poPcCo), and tetra-β-(3-methoxyphenoxy)phthalocyanine cobalt (mpoPcCo)) and reduced graphene oxide (rGO) (RPcCo/rGO) were synthesized via non-covalent interactions as a high performance gas sensing materials for the ppb-level detection of ammonia (NH3). Various characterization techniques, including FT-IR, Raman, UV-vis, TGA, XPS and SEM, were used to confirm the structure, element information and morphology of the as-synthesized materials. The obtained materials were used in interdigital electrodes to fabricate the sensing device, and the gas sensing performance was investigated at room temperature. The obtained sensors exhibited excellent sensitivity, selectivity, good reproducibility and perfect response–concentration linearity towards NH3, which are mainly ascribed to the synergetic effects of RPcCo and rGO due to the specific surface area structure for NH3 diffusion, the abundant active sites to adsorb NH3, and excellent conductivity for efficient electron transport, particularly the effect of RPcCo. For example, the cpoPcCo/rGO-based sensor showed a higher and faster response for low concentration of NH3 (∼2.5 and 45 s for 100 ppb of NH3), a ppb level detection and superior stability over 60 days. Besides, the effect of different phenoxyl substituents of cobalt phthalocyanines on the sensing performance and the sensing mechanism for the sensitivity enhancement were discussed and confirmed by the first-principles density functional theory calculations and electrochemical impedance spectroscopy (EIS).
Highlights
In recent years, various toxic gases have been released due to rapid developments and unforeseen accidents in various industries
An ammonia gas sensor based on polyaniline with N-doped graphene quantum dots was prepared, and showed a response value of 110.92 for 1500 ppm NH3.18 Karaduman et al reported that the reduced graphene oxide (rGO) hybrids showed enhanced NH3-sensing properties by the modi cation of Ag, Au and Pt nanoparticles at room temperature.[19]
Because of the p–p interactions, RPcCo could spontaneously assemble with rGO, generating RPcCo/rGO hybrids
Summary
Graphene nanosheets have attracted considerable attention of scientists, graphene oxide (GO) and reduced graphene oxide (rGO). Doping some heteroatoms in graphene and combining with other gas sensing materials represent a new research method for improving the sensitivity of the hybrid.[17] An ammonia gas sensor based on polyaniline with N-doped graphene quantum dots was prepared, and showed a response value of 110.92 for 1500 ppm NH3.18 Karaduman et al reported that the rGO hybrids showed enhanced NH3-sensing properties by the modi cation of Ag, Au and Pt nanoparticles at room temperature.[19] The rGO-TiO2 hybridbased sensor has shown excellent sensing properties by improving the morphology of rGO sheets due to the introduction of synthetic TiO2.20 it is still a big challenge for GO and rGO hybrids to obtain excellent sensitivity, selectivity, and good stability It is well-known that metal phthalocyanines (MPcs) are good gas sensitive materials due to their unique conjugated 18p-electron structure.[21] There are 16 hydrogen atoms around the phthalocyanine ring, which can be substituted by other groups, such as alkoxy group, carboxyl group, amino group and sulfonic acid group[22,23,24] which provides an opportunity to improve and optimize the NH3-sensing performance of rGO by using substituted MPcs as dopants.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
