Preparation, Photoelectrochemical Properties and Biosensor Applications of Oriented 2-D ZnIn2S4 Nanosheet Arrays for Detecting Glutathione (GSH)

In this study, two-dimensional (2-D) ZnIn2S4 nanosheet arrays (NSAs) have been prepared on the arbitrary substrates directly through a facile one-pot hydrothermal route. The effect of synthesis time, synthesis temperature and substrate type were investigated on the surface morphologies of the obtained ZnIn2S4 membranes. It was found that the optimal growth conditions were 200°C, 2 h and fluorine doped tin oxide (FTO) used as the substrate. Besides, the influence of growth time on the photoelectrochemical (PEC) properties of ZnIn2S4 was investigated. It was demonstrated that the best PEC performance was achieved in the 2 h sample (200°C, FTO substrates), which displayed a photocurrent density of ∼ 1.0 mA/cm2 versus reversible hydrogen electrode under a simulated solar irradiation (AM1.5G, with an intensity of 100 mA/cm2). The Mott–Schottky (M–S) plots indicated that the 2 h sample owned the highest donor density (ND) and the most positive flat-band potential (VFB), suggesting that the enhanced PEC performance might be resulting from a better n-type conductivity of the ZnIn2S4 electrode. Further, the PEC biosensors were fabricated by using a ZnIn2S4 photoanode for detection of the glutathione (GSH), leading to an excellent detect limit of 1500 mA cm−2 M−1 and sensitivity of 33 nM.