Kumar Pankaj, Maikap Siddheswar, Qiu Jian-Tai, Jana Surajit, Roy Anisha, Singh Kanishk, Cheng Hsin-Ming, Chang Mu-Tung, Mahapatra Rajat, Chiu Hsien-Chin, Yang Jer-Ren
Department of Electronic Engineering, Chang Gung University (CGU), 259 Wen-Hwa 1st Rd., Kwei-Shan, Tao-Yuan, 333, Taiwan.
Bio-Sensor Lab., Biomedical Engineering Research Center, Department of Electronic Engineering, Chang Gung University, Tao-Yuan, 333, Taiwan.
Nanoscale Res Lett. 2016 Dec;11(1):434. doi: 10.1186/s11671-016-1657-5. Epub 2016 Sep 29.
A 15-nm-thick GdO x membrane in an electrolyte-insulator-semiconductor (EIS) structure shows a higher pH sensitivity of 54.2 mV/pH and enzyme-free hydrogen peroxide (H2O2) detection than those of the bare SiO2 and 3-nm-thick GdO x membranes for the first time. Polycrystalline grain and higher Gd content of the thicker GdO x films are confirmed by transmission electron microscopy (TEM) and X-ray photo-electron spectroscopy (XPS), respectively. In a thicker GdO x membrane, polycrystalline grain has lower energy gap and Gd(2+) oxidation states lead to change Gd(3+) states in the presence of H2O2, which are confirmed by electron energy loss spectroscopy (EELS). The oxidation/reduction (redox) properties of thicker GdO x membrane with higher Gd content are responsible for detecting H2O2 whereas both bare SiO2 and thinner GdO x membranes do not show sensing. A low detection limit of 1 μM is obtained due to strong catalytic activity of Gd. The reference voltage shift increases with increase of the H2O2 concentration from 1 to 200 μM owing to more generation of Gd(3+) ions, and the H2O2 sensing mechanism has been explained as well.
在电解质-绝缘体-半导体（EIS）结构中，15纳米厚的氧化钆（GdOx）薄膜首次展现出比裸露的二氧化硅（SiO2）薄膜以及3纳米厚的GdOx薄膜更高的pH灵敏度（54.2毫伏/ pH）和无酶过氧化氢（H2O2）检测能力。通过透射电子显微镜（TEM）和X射线光电子能谱（XPS）分别证实了较厚GdOx薄膜的多晶晶粒和更高的钆（Gd）含量。在较厚的GdOx薄膜中，多晶晶粒具有较低的能隙，并且在过氧化氢存在的情况下，Gd(2+)氧化态会转变为Gd(3+)氧化态，这通过电子能量损失谱（EELS）得到证实。具有较高Gd含量的较厚GdOx薄膜的氧化/还原（redox）特性负责检测H2O2，而裸露的SiO2薄膜和较薄的GdOx薄膜均未表现出传感特性。由于Gd的强催化活性，获得了1μM的低检测限。随着H2O2浓度从1μM增加到200μM，参考电压偏移增加，这是由于产生了更多的Gd(3+)离子，同时也对H2O2传感机制进行了解释。
