School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University , Shanghai 200240, PR China.
Inorg Chem. 2013 May 20;52(10):5924-30. doi: 10.1021/ic400109j. Epub 2013 May 7.
Semiconductor-based sensors have played an important role in efficient detection of combustible, flammable, and toxic gases, but they usually need to operate at elevated temperatures (200 °C or higher). Although reducing the operation temperature down to room temperature is of practical significance, it is still a huge challenge to fabricate room temperature sensors with a low cost. Here we show a novel "self-doping" strategy to overcome simultaneously both difficulties of "high resistance" and "low reaction rate", which have always been encountered for room-temperature operation of semiconductor-based sensors. In particular, a porous crystalline titania with heavily self-doped Ti(3+) species has been prepared by using a porous amorphous TiO2 and urea as the starting materials. The resulting Ti(3+) self-doped TiO2 material serves as an efficient room-temperature gas-sensing material for specific CO detection with fast response/recovery. The self-dopant (Ti(3+)) in the titania material has proved to decrease the resistance of TiO2 significantly on the one hand and to increase the chemisorbed oxygen species substantially, thus enhancing the surface reaction activity on the other. Such a self-doping concept is anticipated to give a fresh impetus to rational design of room-temperature sensing devices with low costs.
基于半导体的传感器在高效检测可燃、易燃和有毒气体方面发挥了重要作用，但它们通常需要在高温（200°C 或更高）下运行。虽然将操作温度降低到室温具有实际意义，但制造具有低成本的室温传感器仍然是一个巨大的挑战。在这里，我们展示了一种新颖的“自掺杂”策略，该策略同时克服了半导体基传感器在室温下运行时一直存在的“高电阻”和“低反应速率”这两个难题。具体来说，我们使用多孔无定形 TiO2 和尿素作为起始材料，制备了一种具有大量自掺杂 Ti(3+)的多孔结晶二氧化钛。所得的 Ti(3+)自掺杂 TiO2 材料可用作高效的室温气体传感材料，可用于特定 CO 的检测，具有快速的响应/恢复速度。二氧化钛材料中的自掺杂剂（Ti(3+)）一方面显著降低了 TiO2 的电阻，另一方面大大增加了化学吸附氧物种，从而提高了表面反应活性。这种自掺杂概念有望为低成本的室温传感器件的合理设计提供新的动力。
