Pt-Fe_2O_3复合纳米陶瓷的室温氢敏性能研究

Room-temperature Hydrogen Sensing Capabilities of Pt-Fe_2O_3 Composite Nanoceramics

以Fe_2O_3纳米粉与铂粉为原料,通过压片与烧结,制备出了Pt-Fe_2O_3复合纳米陶瓷。SEM等分析表明,该陶瓷中存在大量纳米尺寸的孔洞,其Fe_2O_3晶粒粒径仅为30 nm。以该陶瓷材料制备的氢气传感器,在室温下对氢气具有显著的响应。对氮气中5%氢气,其电阻下降90余倍,响应时间和在空气中的恢复时间分别约为20和30 s。为了揭示其室温氢敏机理,将氮气中氢气的浓度由5%降低至0%,发现该陶瓷的电阻不随氮气中氢气浓度的下降而发生变化。结果表明,Pt-Fe_2O_3复合纳米陶瓷的室温氢敏现象是由于氢在Pt的催化作用下与吸附氧在室温下发生化学反应而引起的。与之前报道的Ti O_2基陶瓷材料的室温氢敏现象相比,Fe_2O_3基陶瓷材料的室温氢敏性能与机理均存在显著的差别,因此有必要对金属氧化物半导体基陶瓷材料的室温氢敏现象进行深入系统的研究。

Pt-Fe_2O_3 composite nanoceramics were prepared from Pt and Fe_2O_(3 )nanoparticles through traditional pressing and sintering.SEM analyses show that numerous nanosized pores are present in the ceramics and Fe_2O_(3 )grains are around 30 nm in size.Sensors based-on the nanoceramics show strong responses to hydrogen at room temperature.To 5%H_2 in N_2,the sensitivity is decreased by 90times,and the response and recovery times are 20 and 30 s,respectively.To explore the room-temperature hydrogen sensing mechanism,hydrogen concentration in surrounding N_2 is decreased from 5%to 0%.The resistance of the sensors exhibits no response to the hydrogen concentration variation.It indicates that hydrogen-induced decrease in resistance of Fe_2O_(3 )results from the reaction between chemisorbed oxygen on Fe_2O_3 and hydrogen at room temperature with the catalytic effect of Pt.Fe_2O_3-based ceramics are quite different from TiO_2-based ceramics in room-temperature hydrogen sensing properties and mechanism,and systematic investigations should be conducted on room-temperature hydrogen sensing of various metal oxide semiconductor ceramics.