Spatial heterogeneous is one of the important features for thermal catalysis on heterogeneous catalysts. These local environments strongly affect the macroscopic properties. In artificial photocatalysis, the situation becomes even more challenge and complex: most of the elementary surface reactions of photocatalysis involve charge transfer processes. The spatial distribution of photogenerated charge carriers becomes a new and important factor to determine the overall performance of photocatalysis.
Herein, making use of the newly developed photoelectrical imaging technique, the distribution of photogenerated charges on the surface and across the interface of semiconductor photocatalyst is revealed. It is found that built-in electric field plays quite important roles in the spatially separated charges. Several exemplifications will be demonstrated: the anisotropic space charge region in the different facets of single crystal semiconductor1,2, the inverted built-in electric fields in semiconductor photocatalyst aligned by cocatalyst3, and the effectively formed built-in electric field across the nano scale interface of anatase and rutile nanoparticles4. Moreover, the charge separation affected by the external fields such as asymmetric illumination and local enhanced electromagnetic fields will be also discussed. These results give deep insights into the nature of photogenerated charge separation in a single semiconductor photocatalyst particle and provide the scientific basis for enhancing the performance of solar chemical-conversion devices.
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2. J. Zhu, F.T. Fan, R.T. Chen, H.Y. An. Z.C. Feng, C. Li., Angew. Chem. 54(2015), 9111;
3. J. Zhu, S. Pang, T. Dittrich, F.T. Fan, C. Li. et al. Nano Lett. (2017), ASAP;
4. Y. Gao. J. Zhu, F.T. Fan, C. Li. et al. J. Phys. Chem. Lett. ( 2017), 8, 1419.