双金属驱动Z型光催化材料的制备及其在光催化全分解水中的应用研究

Z-scheme photocatlaysts have exhibited a broad application prospect on photocatalytic overall water splitting. However, photo-generated electrons and holes are recombined as they inclined to transport to the carriers’ transmission media thermodynamically. It causes the low separation efficiency of high energy photo-generated carriers and low solar-to-hydrogen energy conversion efficiency of Z-scheme photocatlaysts. For this problem, we demonstrate a conceptually new approach: changing the structure of Z-scheme photocatlaysts from photocatlaysts/metal/photocatlaysts to photocatlaysts/metal A/metal B/photocatlaysts. The contact of two kinds of metals forming contact potential difference, we apply the contact potential difference to separate the high energy photo-generated carriers to split water in photocatalysts and attract the low energy photo-generated carriers into the metal to make recombination. Thus, the selective separation and recombination of photo-generated carriers could be realized, when using the bimetal to control their transportation. NaCl is selected as template to synthesize photocatlaysts/metal A/metal B/photocatlaysts multilayer structure and realize the off-site deposition of cocatalysts, thereby forming desired structure of materials. Then we can investigate the regulation rule, mechanism of photo-generated carriers under the control of contact potential difference, realize the controllable transportation of photo-generated carriers and improve the separation efficiency of high energy photo-generated carriers in Z-scheme photocatalysts. Finally, we hope obtain the bimetal Z-scheme photocatalysts with at least 10 % quantum efficiency and 2 % solar-hydrogen conversion efficiency for overall water splitting under visible light.

Z型光催化材料在光催化全分解水方面具有广阔的应用前景，但其光生电子、空穴在热力学上倾向于输运至传输介质（金属）复合，降低了高能光生载流子的分离效率，造成光-氢转换效率的低下。针对这个问题，本课题组提出新的概念：Z型光催化材料的结构由光催化剂/金属/光催化剂改为光催化剂/金属A/金属B/光催化剂。金属接触形成接触电势差分离高能光生载流子使其保留在光催化剂内部分解水；吸引低能光生载流子进入金属内部复合。这样双金属就驱动了光生载流子的输运，实现选择性分离和复合。我们设计氯化钠模板法制备光催化剂/金属A/金属B/光催化剂多层结构，离域沉积助催化剂，制备出理想的材料结构；探究金属接触电势差对光生载流子输运的调控机制和规律，实现载流子可控输运和高能光生载流子的高效分离。最终获得可见光下全分解水产氢量子转换效率不低于10%，光能-氢能转换效率不低于2%的双金属Z型光催化材料。

Z型光催化材料在光催化全分解水方面具有广阔的应用前景，但其光生电子、空穴在热力学上倾向于输运至传输介质（金属）复合，降低了高能光生载流子的分离效率，造成光-氢转换效率的低下。针对这个问题，本课题组提出新的概念：Z型光催化材料的结构由光催化剂/金属/光催化剂改为光催化剂/金属A/金属B/光催化剂。金属接触形成接触电势差分离高能光生载流子使其保留在光催化剂内部分解水；吸引低能光生载流子进入金属内部复合。这样双金属就驱动了光生载流子的输运，实现选择性分离和复合。我们设计氯化钠模板法制备光催化剂/金属A/金属B/光催化剂多层结构，离域沉积助催化剂，制备出理想的材料结构；探究金属接触电势差对光生载流子输运的调控机制和规律，实现载流子可控输运和高能光生载流子的高效分离。在此我们开发了新型的光驱动催化系统，基于选择性光吸收原理构建了新型光热系统，在一个标准太阳光辐照下可产生250-300℃的高温。此外，我们还基于模板法开发了一系列新型催化剂。结果表明，在自然太阳光辐照下，新型光热系统和催化剂在CO2甲烷化、CO氧化、NOx脱除、VOCs燃烧、甲醇、水、CO制氢等方面均表现出创纪录的性能，并且该系统可以大规模量产，显示出工业应用的潜力。