物理化学学报 >> 2015, Vol. 31 >> Issue (10): 2005-2010.doi: 10.3866/PKU.WHXB201509071

材料物理化学 上一篇    下一篇

孔隙结构可调的Cu2O球状纳米结构及其NO2气体传感性质

张东凤,张岩,张华,齐娟娟,商旸,郭林*()   

  • 收稿日期:2015-05-22 发布日期:2015-10-10
  • 通讯作者: 郭林 E-mail:guolin@buaa.edu.cn
  • 基金资助:
    国家自然科学基金(21173015)

Cavity-Tunable Cu2O Spherical Nanostructures and Their NO2 Gas Sensing Properties

Dong-Feng. ZHANG,Yan. ZHANG,Hua. ZHANG,Juan-Juan. QI,Yang. SHANG,Lin. GUO*()   

  • Received:2015-05-22 Published:2015-10-10
  • Contact: Lin. GUO E-mail:guolin@buaa.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(21173015)

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摘要：

报道在聚乙烯吡咯烷酮(PVP)的协助作用下,通过简单调节OH-离子的浓度及Cu2+的释放速度,将Cu2O调节为具有不同空腔特征(介孔、空心及实心)结构的纳米球.研究表明, OH-根离子的扩散动力学是决定产物结构的关键因素.当[OH-] > 0.05 mol·L-1时,高的化学势使其迅速扩散到PVP胶团内部,与吸附在PVP链上的Cu2+反应形成Cu(OH)2,在抗坏血酸(Vc)的还原作用下经过重结晶得到Cu2O实心球纳米结构;当[OH-] < 0.025 mol·L-1时,其扩散速度下降,首先与吸附在PVP胶团外部的Cu2+反应形成Cu(OH)2, Cu(OH)2的形成阻碍了OH-离子的向内扩散,形成具有较大空腔(~220 nm)的空心球;当0.025 mol·L-1 < [OH-] < 0.05 mol·L-1时,形成较小空腔(30-60 nm)的空心球.以NH3水为OH-缓释源时,虽然OH-浓度较低,但同时Cu2+的浓度也低,胶团外部形成的Cu(OH)2不足以阻碍OH-离子的向内扩散,反应过程中NH3的释放及较低的OH-浓度阻碍了重结晶的发生,从而形成Cu2O介孔纳米球.对三种典型结构特征的产物进行了NO2气体传感性质研究,结果表明, Cu2O介孔纳米球相比空心结构和实心结构具有更为优异的响应性.结合比表面积数据,我们认为介孔纳米球疏散的结构有利于NO2气体的扩散和O2的吸附,从而表现出了更灵敏的气体传感性.

关键词: Cu2O, 纳米球, 孔隙可调, 气敏性能, 扩散控制

Abstract:

We report the preparation of cavity-controlled Cu2O nanospheres, having various mesoporous, hollow, and solid structures, by simply adjusting the OH- concentration and the release rate of Cu2+ with the assistance of polyvinyl pyrrolidone (PVP). It indicates that the OH- diffusion kinetics is the key factor that determines the morphology of the products. For [OH-] > 0.05 mol·L-1, the high chemical potential made them rapidly diffuse into the PVP micelle interiors. Adsorbed Cu2+ on the PVP produced Cu(OH)2, which was subsequently reduced to Cu2O. After re-crystallization, Cu2O solid spheres formed. For [OH-] < 0.025 mol·L-1, the OH- diffusion rate was reduced, and the Cu(OH)2 layer on the PVP micelles blocked diffusion into the interior. After re-crystallization, Cu2O hollow spheres had large cavities (~220 nm). For 0.025 mol·L-1 < [OH-] < 0.05 mol·L-1, hollow spheres with smaller cavities (30-60 nm) formed. When an aqueous NH3 solution was the OH- source, although the concentration of OH- is low, the small amount of Cu(OH)2 formed with the limited Cu2+ was not enough to block OH- diffusion into the micelles. The free NH3 and the low OH- concentration did not promote re-crystallization; thus, mesoporous Cu2O spheres were formed. We characterized NO2 gas sensing of the three structures. The porous structures exhibited more sensitivity than did the hollow or solid structures. Together with the specific surface area data, the improved gas sensitivity suggests that the open structure of the mesoporous spheres facilitates NO2 diffusion and O2 adsorption.

Key words: Cu2O, Nanosphere, Cavity-tunable, Gas sensitivity, Diffusion-controlled