Grain boundaries dependent hydrogen sensitivity in MAO-TiO2 thin films sensors

作者：Ren Fujian; Huang Liang; Ling Yunhan^*; Feng Jiayou

来源：Sensors and Actuators B: Chemical , 2010, 148(1): 195-199.

DOI：10.1016/j.snb.2010.05.014

• Grain boundaries
• Thin films
• TiO2
• Sensors

Anatase TiO2 thin films were fabricated on titanium substrates by micro-arc oxidation (MAO) process and their hydrogen sensing properties were investigated. The obtained films exhibited the maximum H-2 gas response at 250 degrees C but showed no response at the temperature above 300 degrees C. Electrochemical impedance spectroscopy (EIS) was applied to investigate the gas sensing mechanism. EIS analysis on the as-prepared MAO-TiO2 films with limited porosity reveals that the equivalent electron transfer circuit of grain and grain boundary could be represented electrochemically by a resistor and a constant phase element (CPE) in parallel, respectively, by which a possible surface-controlled gas sensing mechanism is proposed. It is found that temperature dependent grain boundary is a crucial factor governing the gas sensing properties.

• 出版日期2010-6-30
• 单位清华大学