摘要
通过简单快速且无添加剂的氨水可控沉淀法在水溶液中制备具有新型形貌和均匀纳米结构的氧化锌粉末。用SEM、XRD、FTIR、TG/DTA等检测手段表征所制备的固体粉末。FTIR分析结果显示:纳米结构形貌对所制备材料的红外光谱影响较小。将原始态(ZnO-AP)、烧结态(ZnO-Cal)和商业(ZnO-Com)纳米结构ZnO制作成气敏元件,并在室温(29℃)下检测其对氨气、丙酮和酒精的气敏性能。结果表明,ZnO-AP和ZnO-Cal气敏元件对1×10^(-6)的氨气表现出优良的气敏性能和可重复性,灵敏度分别为63.79%和66.87%,响应和恢复时间分别为13和3 s;这是由于合成的纳米结构具有独特的形貌和优异的形状与尺寸均匀性。相反,ZnO-Com气敏元件对浓度200×10^(-6)以下的氨气没有响应。另外,ZnO-Cal在室温下对氨气的选择性高于对丙酮和酒精的选择性。总之,合成的ZnO对氨气的最低检测限为1×10^(-6),表明其具有优异的气敏特性。
Zinc oxide uniform nanostructures with novel morphologies were synthesized through simple and fast ammonia based controlled precipitation method in aqueous media and in the absence of any additive. Selected batches of the synthesized solids were characterized by SEM, XRD, FTIR and TG/DTA. FTIR analysis revealed that the morphology of nanostructures had little effect on their IR spectral profile of the synthesized material. The as-prepared, calcined and commercial ZnO nanostructures (ZnO-AP, ZnO-Cal and ZnO-Com) were then employed as gas sensors for the detection of ammonia, acetone and ethanol. ZnO-AP and ZnO-Cal based sensors showed superior and reproducible performance towards 1×10^-6 ammonia with gas response of 63.79% and 66.87% and response/recovery time of 13 and 3 s, respectively, at room temperature (29℃). This was attributed to the unique morphology and remarkable uniformity in shape and size of the synthesized nanostructures. In contrast, the ZnO-Com based sensor did not respond to ammonia concentration less than 200×10^-6. In addition, ZnO-Cal showed high selectivity to ammonia as compared to acetone and ethanol at room temperature. Moreover, the lowest detection limit was 1×10^-6, which demonstrates excellent ammonia sensing characteristics of the synthesized ZnO.
