(24b) Nanocrystalline Doped Sno2 for Room Temperature Detection of Hydrogen; Recovery and Response Improvements

Current hydrogen sensor issues are use at lower temperatures and fast detection. Use of nanomaterials in sensors may improve detection limits to lower temperatures by alterations of the space charge layer. The surface reaction which identifies H2 on the sensor is improved when the number of defect sites for reaction are increased .

Nano In-SnO2 is synthesized using sol-gel method with for ppm level H2 sensing at room temperature. Its sensing is based on variations of the depletion layer in the presence of a reducing or oxidizing gas, which leads to a variation in the height of the energy barriers for free charge carriers. Conduction electrons have to overcome a potential barrier induced by the space charge layer. Doping with indium enhances the conductivity response within the SnO2 lattice. Ceria, due to its multi-valence states, has oxygen storage and release capabilities. It will be incorporated within the In-SnO2. In an oxygen-free environment, CeO2 would release stored oxygen to In-SnO2 to recover its original resistance

Variations in doping amount of indium for increased response are being investigated for generation of excess oxygen-ion vacancy concentration. Doping in the amounts of 1%. 3%, 6.5%, and 9% will give insight to the optimal doping amounts for room temperature sensing using the sol gel method to derive nanocrystalline SnO2. Variations in doping amounts of Ceria are also being investigated. Preliminary results show that room temperature sensing of hydrogen can been achieved using this system. Preliminary results have also shown that doping with Ceria can reduce the recovery time to under a minute, recovering approximately 95% of the sensor's original conductivity.