Enhancing charge separation on high symmetry SrTiO3 exposed with anisotropic facets for photocatalytic water splitting
Enhancing charge separation on high symmetry SrTiO3 exposed with anisotropic facets for photocatalytic water splitting
复制标题
增强暴露有各向异性面的高对称性 SrTiO3 的电荷分离，用于光催化水分解
DOI：
10.1039/c6ee00526h
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发表时间：
2016-01-01
影响因子：
32.5
通讯作者：
Li, Can
中科院分区：
文献类型：
--
作者：
Mu, Linchao;Zhao, Yue;Li, Can
光催化整体水分解中的挑战性问题之一是有效地分离光生电荷以及基于光催化剂的光催化剂上的还原和氧化催化位点。据报道，光生电荷可以在具有低对称性的半导体晶体的不同面之间分离。然而，许多半导体晶体具有高对称性（例如立方相）并且暴露各向同性小面，这不适合于小面之间的电荷分离。在此，使用一个独特的形貌剪裁策略，我们合成了高对称性SrTiO 3纳米晶体的暴露面从各向同性的小面（6面SrTiO 3）到各向异性的小面（18面SrTiO 3），这导致不同的晶体小面的暴露。我们发现，18面SrTiO3纳米晶的各向异性晶面上存在氧化还原催化位，而6面SrTiO3纳米晶的各向异性晶面上存在氧化还原催化位.基于这些发现，双助催化剂的选择性分布在各向异性方面的18面SrTiO 3纳米晶体导致表观量子效率的五倍增强。该上级性能可归因于各向异性刻面之间的电荷分离以及还原和氧化催化位点的分离以减少电荷复合。研究结果对合理设计高效的光催化太阳能转化系统具有指导意义。
One of the challenging issues in photocatalytic overall water splitting is to efficiently separate the photogenerated charges and the reduction and oxidation catalytic sites on semiconductor-based photocatalysts. It has been reported that the photogenerated charge can be separated between different facets of a semiconductor crystal with low symmetry. However, many semiconductor crystals possess high symmetry (such as the cubic phase) and expose isotropic facets, which are not suitable for charge separation between the facets. Herein, using a nanocrystal morphology tailoring strategy, we synthesized the exposed facets of high symmetry SrTiO3 nanocrystals from isotropic facets (6-facet SrTiO3) to anisotropic facets (18-facet SrTiO3), which leads to the exposure of different crystal facets. We found that the reduction and oxidation catalytic sites can be separately distributed only on the anisotropic facets of 18-facet SrTiO3 nanocrystals, but randomly distributed on every facet of 6-facet SrTiO3 nanocrystals. Based on these findings, the selective distribution of dual-cocatalysts on the anisotropic facets of 18-facet SrTiO3 nanocrystals leads to a fivefold enhancement of apparent quantum efficiency. The superior performance can be attributed to the charge separation between anisotropic facets and the separation of the reduction and oxidation catalytic sites to reduce the charge recombination. These findings will be instructive for the rational design of a high efficiency photocatalytic system for solar energy conversion.