Abstract
Many researches about biosensors have used Glass Carbon Electrode (GCE) as the host electrode for sensing catalysts, because it is easy to drop the catalysts onto the GCE and used it for sensing. If we want to make an ideal sensor electrode, the most important thing is to choose not only the appropriate catalysts but also the host electrode. Host electrodes need good electric conductivities to rapidly transfer the electronic signals, produced by the sensing reaction. With good hydrophilicity and high interficial areas, the host electrode can enhance the contact with the target components. In this study, we utilized a previously developed technique to modify commercial FTO glass, and improved on the low hydrophilicity and interficial areas of the commercial FTO, providing a choice of substitution for the GCE. In the first part of this study, we used a simple electrochemical treatment to modify the commercial FTO glass. After a series of fabrications, we produced porous FTO with an extraordinary conductivity and good hydrophilicity as we concocted the concentration of SnCl4‧H2O to 0.07 M. A well-developed porous structure was acquired. Comparing to the commercial FTO, the porous FTO possessed high porosities and the roughness was enhanced to 18~36 nm. The static contact angle dropped from 36.1 to 4.4o, and the sheet resistance was about 17.1 Ω□-1. We proceeded with the electrochemical sensing for applications in H2O2 sensing through Pt-loading. As a result, the high porosity enabled a uniform distribution of Pt nanoparticles on the FTO pore surface. The porous FTO was good for Pt loading. This sample showed a high sensitivity of 25.8 mA/Mcm2, ten times of that of the commercial FTO (2.68 mA/Mcm2). For the second part of the study, by using a one-step carrier solvent assisted interfacial reaction process, we successfully synthesized SnFe2O4 nanocrystals, intended for the replacement of Pt. In the experiment, we adjusted the concentration of NaOH to 1M, so that we can obtain SnFe2O4 nanocrystals, which can catalyze reduction of H2O2. After loading it to the porous FTO electrode surface, the static contact angle is about 4.68o, the sensitivity of sensing H2O2 was up to 1027 mA/Mcm2, which is much higher than most of the number indicated by the references using Pt with FTO and ITO, and GCE as the sensing electrode over the past ten years. But comparing to Pt, SnFe2O4 is not toxic and much cheaper. So this study successfully develops a promising and novel nanomaterial, which is an excellent catalyst, and has a good potential to replace Pt as the sensing catalyst.