Phosphorene Modified Zinc Oxide for Extended-Gate Field-Effect Transistor pH Sensors

In this study, we prepare a pH sensor based on the extended gate field-effect transistor (EGFET), in that phosphorene (PP), which is one type of 2-D materials, is used to modify the zinc oxide (ZnO) sensing electrode. Preparation of PP is performed by using the liquid-phase exfoliation (LPE) method, while the sensing electrode is realized by spin-coating the PP-modified ZnO colloid onto the fluorine-doped tin oxide (FTO) glass. Sensing characteristics of the prepared EGFET pH sensors, including linearity, sensitivity, hysteresis, and drift effect are investigated. It is found that the PP-modified ZnO pH sensor exhibits a sensitivity of 62.5 mV/pH and a linearity of 0.993, respectively, along with a hysteresis voltage of 10 mV and a drift rate of 0.714 mV/h. This study highlights the potential of PP-modified ZnO sensors for accurate and reliable pH measurement, laying the groundwork for further exploration in biomedical sensing applications.