Cellulose acetate nanofibers coated layer-by-layer with polyethylenimine and graphene oxide on a quartz crystal microbalance for use as a highly sensitive ammonia sensor.

A novel approach to the preparation of a sensing coating on a quartz crystal microbalance (QCM) to realize rapid and accurate ammonia detection is reported in this study. Positively charged polyethylenimine (PEI) and negatively charged graphene oxide (GO) were successively assembled on the surfaces of negatively charged electrospun cellulose acetate (CA) nanofibers, using the electrostatic layer-by-layer (LBL) self-assembly technique. Scanning electron microscopy (SEM) images demonstrated the nanofibrous morphology of the as-prepared CA/PEI/GO membrane. Fourier-transform infrared (FT-IR) and Raman analyses indicated that the PEI and GO were successfully assembled on the surfaces of the CA nanofibers. In gas-sensing tests, the CA/PEI/GO-based QCM sensor not only exhibited a low detection limit and rapid response, but also performed with good reversibility and selectivity with respect to ammonia detection.