Temperature effects on the electrocatalytic activities of carbon nanotube/poly(N-isopropylacrylamide) composites

Abstract

This study investigates the electrocatalytic activities of carbon nanotubes (CNTs) in temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) composites with a low critical solution temperature of about 32°C. The composite cast on a glassy carbon electrode (GCE) as working electrode was investigated by cyclic voltammetry (CV) using potassium ferricyanide as a probe. The factors examined included the temperature (25 and 37°C, denoted as 25f and 37f) at which GCE was modified, content of CNT in the composite, acid treatment of CNT, and working temperature (25 and 37°C, denoted as 25aq and 37aq) of GCE. The CV data revealed that a higher content of CNT and COOH-functionalized CNT (fCNT) in the composite exhibited a higher electrocatalytic activity. The electrocatalytic activity of the modified GCE was also found to be significantly temperature dependent. The fCNT/PNIPAAm composite with the 25f–37aq temperature combination exhibited strong electrocatalytic activity and highly selective detection ability for the three analytes (dopamine, uric acid, and ascorbic acid). In contrast, the same composite with the other three combinations (25f–25aq, 37f–25aq, and 37f–37aq) and the CNT/PNIPAAm composite with all four combinations exhibited insignificant electrocatalytic activity and no selective detection ability.