高效光分解水的Co3O4纳米材料制备及其电子学特性研究

Photocatalytic water splitting is the optimal method to produce hydrogen. It is reported that a number of nano-semiconducting metal oxides, which have photocatalytic activity, can split the water under solar light. But the low efficiency of solar energy utilization and high excitation energy make the photocatalytic water splitting for hydrogen difficult for the wide application, using the present system designed with semiconducting metal oxides, such as TiO2. Friendly Co3O4 with a bandgap of about 2.1 eV has attracted much attention due to its low cost in terms of photocatalytic water splitting for hydrogen. The energy level structure of photocatalyst and the characteristics of electronics are considered as the core issues of water splitting. In this project, Co3O4 nanomaterial with high specific surface area is synthesized using degreasing cotton as a dispersant and carbon source.Co3O4 with surface disordered structure as a durable and efficient photocatalyst is prepared by hydrotreating to broaden its spectral absorption, and then modified through the metal and nonmetal doping to change its energy level structure. Furthermore through decorating with precious metals and combining with semiconductor TiO2 to reduce the recombination rate of the photo-generated electron-hole, the photocatalytic activity of Co3O4 is improved in the process of water splitting for hydrogen under visible light. The project can lay a solid foundation in solving the problems of energy and environmental pollution.

利用光能分解水制氢是最理想的绿色制造氢气的方式。研究发现利用一些具有光催化活性的纳米半导体金属氧化物可实现水的光分解，但目前利用金属氧化物（如TiO2）设计的光解水制氢系统对太阳能的利用效率低，所需激发能量较高，不宜推广。Co3O4因具有适宜的带宽、低廉的价格、环境友好等特性在光解水方面受到较多关注。而提高光解水效率的核心问题是系统研究光催化剂材料的能级结构等电子学特性，因此本课题拟采用脱脂棉作为分散剂和碳源来合成具有高比表面积的Co3O4，通过氢化处理制备出一种寿命长且效率高的表面无序结构光催化剂, 拓宽其光谱吸收范围; 继而通过金属、非金属掺杂改变其能级结构以及贵金属修饰、与半导体TiO2复合等方式减小光生电子和空穴湮灭几率，提高Co3O4纳米材料在可见光下的光催化活性，高效吸收太阳光进行光解水制氢，为解决能源与环境污染问题奠定坚实的基础。

能源是人类生存都基础，光水解是一种理想的绿色能源准备方法，因此对高效稳定的光催化剂研究成为必然。Co3O4 因其较窄的带宽（2.1 eV）、优异的氧化能力（价带顶较低）、环境友好以及价格低廉等性能在光解水制氧领域受到了较多关注。.本项目研究过程中通过多种方法研制了高比表面积Co3O4纳米颗粒，并通过金属、非金属掺杂以及贵金属修饰成Co3O4/ZnO，Co3O4/TiO2，Co3O4/C3N4，Co3O4/C3N4/Pt等多种复合微纳米材料，通过XRD、SEM、FT-IR和Raman等测试手段对制备的材料进行了表征，研究了制备工艺过程中诸多参数对所制备Co3O4基微纳米材料的电子学特性和光催化性能的影响。研究发现Co3O4的能级结构在与n型半导体（ZnO，TiO2等）复合和贵金属（Pt等）修饰等过程中发生了变化，从而使其光催化性能大大提高。本项目所研制的Co3O4基微纳米半导体金属氧化物材料还可以实现水的光分解。研究中以脱脂棉为模板所制备的p-Co3O4/n-TiO2复合材料的BET比表面积为39.64m2/g，平均孔径为3.83nm，在可见光辐照下H2和O2的最佳生产速率分别为8.16μmol/g·L和4.0μmol /g·L，其中H2析出率比纯Co3O4纳米粒子高25%。在与C3N4和Pt复合过程中以2% C3N4和0.25%Pt含量制备的复合颗粒的光解水性能最好。.在该项目的研究基础上，共培养1名博士研究生和3名硕士研究生，项目组成员共发表论文12篇，其中SCI收录7篇。该项目的研究结果为解决能源与环境污染问题奠定了坚实的基础。