Preparation And Characterization Of The Dissolved Oxygen Sensor Based On Palladium、Nitrogen Doped Nano Titania

The monitoring of dissolved oxygen has a great significance in medicine,environmental sciences, industrial water treatment and food processing area. Especially inthe water quality control and water treatment, dissolved oxygen level is an importantindicator. In recent years, people focused on the preparation and measurement devices toimprove technology, exploration, and electrochemical measurement method for the studyof dissolved oxygen sensor, because of its high selectivity, sensitivity, fast response,etc. In this paper, we synthesized a Pd, N co-doped nano-TiO₂as the oxygen-sensitivematerial, and modified on the glassy carbon electrode as a probe to build a high efficiencydissolved oxygen sensor, and tested the feasibility of it.The nano-Pd-N-TiO₂samples were characterized by X-ray diffraction （XRD）,transmission electron microscopy （TEM）, X-ray photoelectron spectroscopy （XPS） andBET specific surface area for its morphology, composition and performance. The modifiedelectrode used cyclic voltammetry （CV） and eletrochemical impedance spectroscopy （EIS）for electrochemical performance testings, the modified electrodes has been optimized andwe chose the best testing conditions. The effect of dissolved oxygen, water and toxicsubstances for the effective lethal concentration determination have been tested. Theresults are as follows:Nano-Pd-N-TiO₂powder samples was prepared by sol-gel method, the Pd dopingamount is0.5%,1.0%and1.5%, the average particle size was7.28nm,8.04nm and8.72nm, the absorption of N2desorption studies have showed that the adsorption average poresize of4.178nm, BET specific surface area of145.2m2/g of1.0%Pd-N-TiO₂. Thepresence of Nafion membrane has some obstacles for the electron transfer process tosome degrees, but overall the catalytic performance of GC electrode has been significantlyimproved. We tested the effects of pH, doping amount of Pd, and the scan rate, chose thepH=6.5,0.01M phosphate buffer solution as the test substrate, the doping amount of Pdis1.0%, and the scan rate is80mV/s as the optimal test conditions. In the phosphatebuffer （pH=6.5,0.01M）, modified electrode studies have shown an excellent linearitywhich was obtained in the range of0.6⁷.2mg/L, R=0.9909, and the detection limit is0.22mg/L. The modified electrode was succesfully applied to determinationt of the dissolved oxygen in waste water, and the stability of it is good. In the growth process ofalgal, the responsive of oxygen generation rate is sensitive and fast. The inhibition of oleicacid imidazoline when its concentration is30mg/L is conspicuous.