Glutaraldehyde-Crosslinked Chitosan and Zinc Oxide Coating Reinforced with Polysulfone on Copper as a Platform for Electrochemical Formaldehyde Sensing

Abstract

Formaldehyde monitoring requires electrochemical platforms with stable structures and reliable interfacial responses. This study aimed to prepare and characterize a Cu|CS–GLA/ZnO–PSf composite film on a copper substrate as a platform for further formaldehyde-sensing development. The film was characterized using FTIR, SEM–EDX, XRD, and cyclic voltammetry. FTIR supported the presence of features associated with chitosan, imine, polysulfone, and Zn–O, while SEM–EDX revealed a heterogeneous polymer-rich coating with Zn- and O-containing domains distributed non-uniformly. XRD indicated a predominantly amorphous or poorly crystalline structure. Cyclic voltammetry showed scan-rate-dependent peak separations, with ΔEp increasing from 0.632 to 0.777 V in citrate buffer and from 0.320 to 0.560 V in the ferri/ferrocyanide system, indicating strongly non-ideal interfacial kinetics. Overall, the Cu|CS–GLA/ZnO–PSf interface provides a structurally and electrochemically characterized basis for further formaldehyde-sensing development.