TiN浸渍-热分解法制备IrOx-TiO2粉体催化剂及其表征

以纳米TiN粉体为前驱体反应物, 采用浸渍-热分解法制备了n(Ir)∶n(Ti)比为1∶6.5的IrOx-TiO2水电解用纳米粉体催化剂. 通过XPS, XRD, TEM和极化曲线等测试手段对其组成、结构、形貌和性能进行了表征. 结果表明, 在350 ℃的热分解温度下, 纳米TiN转化为金红石相TiO2, 铱则以多种价态存在, 与TiO2形成二元氧化物固溶体, 并且在该固溶体表面存在富集Ir的颗粒, 其平均粒径约为7 nm. 将经500 ℃退火处理的IrOx-TiO2粉体作为析氧阳极催化剂, 在SPE水电解中的测试结果表明, 其具有很高的电催化性能, 在铱担载量为1.2 mg/cm2, 电解温度80 ℃, 工作电流密度1 A/cm2条件下, 槽压为1.6 V. 上述实验结果表明, TiN浸渍-热分解法是制备低载量, 高催化性能的水电解催化剂的理想途径.

Syntheses of IrOx-TiO2 Nano-powers from TiN via Impregnationthermal Decomposition Method and Its Characterization

Nano IrOx-TiO2 catalyst with a n(Ir)∶n(Ti) ratio of 1∶6.5 was synthesized from the TiN nano-particle precursors via the impregnation-thermal decomposition method. XPS, XRD, TEM and anodic polarization curve techniques were used to characterize the composition, size, distribution and morphology of the catalyst. The results indicate that TiN were converted to TiO2 rutile-type phase at 350 ℃ and Ir presented as multi-value oxides. TiO2 and IrOx formed a binary solid solution in a rutile phase. A great number of Ir particles with an average crystal size of about 5—10 nm were rich on the surface of the solid solution. After annealing at 500 ℃ for 1 h, a partly sintering of the oxides could be observed and part of Ir was separated from the solid solution. The polarization curves measured in 0.5 mol/L H2SO4 also proved the high-temperature treatment would reduce the activity but beneficial to stability. The catalyst samples annealed at 500 ℃ were achieved. The electrolytic voltage was 1.6 V at 1 A/cm2 and 80 ℃, with Ir loading of only 1.2 mg/cm2. These results suggest that this new method is an efficient way to synthesize noble metal oxides catalyst with a high activity and low cost for water electrolysis.