Enhancement humidity sensing properties of graphene oxide/Poly(ethyleneimine) film QCM sensors

In this work, a novel graphene oxide (GO)/Poly(ethyleneimine) (PEI) layered film was prepared on the quartz crystal microbalance (QCM) by feasible spray process for the humidity detection. The morphology of sensitive film was analyzed by field emission scanning electron microscopy (FESEM). it was worth mentioning that a chemical bonding could be formed at the interface between PEI and GO sheets due to the acylation reaction, which was proved by the Fourier transform infrared (FTIR) transmission spectrum characterization. The humidity-sensing results showed that the frequency shift of sensors exhibited the excellent response and reproducibility, which might be partly ascribed to the effective interaction between PEI and GO. Meanwhile, an instant recovery time (5s) and negligible humidity hysteresis (less than 1%RH) were achieved. Furthermore, the mechanism of performance enhancement of layered film sensors was analyzed.