Fabrication of branched nanostructures for CNT@Ag nano-hybrids: application in CO2 gas detection

Abstract

Nanostructures possess interesting particle dimensions, high surface areas, improved solubility, biological adsorption and improved electrochemical behavior. Based on the properties of nanostructures compared to their bulk counterparts, a hybrid material has been developed using carbon nanotubes (CNTs) and silver (Ag) nanoparticles. CNTs were grown using a chemical vapor deposition (CVD) method and then purified and functionalized using an acidic mixture. Silver nanoparticles were generated through the reduction of AgNO₃ using NaBH₄ and during the progression of reaction, Ag ions were trapped in the COOH linkage of an acid functionalized CNT, which resulted in decoration of Ag nanoparticles on the surface of the CNT. Three different concentrations of nano-hybrids were developed by varying the amount of Ag nanoparticles. The CNT@Ag nano-hybrids were successfully characterized using SEM, TEM, EDX, BET, XRD and FTIR. It was observed from SEM micrographs that the variation in concentrations of reactants resulted in modulation of the morphology of CNT@Ag nano-hybrid. Electrochemical and photo-physical behaviours were tested for the developed nano-hybrids. The synthesized CNT@Ag nano-hybrid was used to monitor and control toxic gases, where an attempt was made to detect CO₂ in an aqueous medium using developed nano-hybrids via an electrochemical route. Results showed that the proposed sensor exhibited a significant response towards the detection of CO₂ with a detection limit of 52 nM, and it also converted CO₂ to oxalates.