pH-dependence in facet-selective photo-deposition of metals and metal oxides on semiconductor particles

Igor Sîretanu, YuXi Guo, Bastian Timo Mei, Xiaowei Li, Hongwei Huang, Guido Mul, Friedrich Gunther Mugele

Research output: Contribution to conferencePoster

Abstract

Facet-engineering and the deposition of co-catalysts lead to improvement in efficiency of semiconductors in photocatalytic applications. While facet-based charge separation is a known phenomenon and it is reported for a range of semiconductors, there is still a limited understanding of it and the mechanism behind remain elusive. Moreover, the proposed simplistic mechanism based on an offset of the valence band and conduction band of different facets is debated. Here, we show that facet-selective, photo-induced reductive or oxidative deposition of co-catalysts onto plate-like bismuth-oxy-bromide (BiOBr) nanoparticles is strongly pH-dependent. High resolution atomic force microscopy and spectroscopy measurements demonstrate that the effect of pH is caused by a reversal of the surface charge of the 001 facets upon increasing the pH from 3 to 9 (isoelectric point 5), while the side facets remain (increasingly) negatively-charged. We propose a different mechanism and we suggest that differences in surface charge/band bending that vary for different surface orientations is the dominant element causing selective charge transport between different facets and metal-oxide deposition.
Original languageEnglish
Publication statusPublished - 17 Sep 2018
Event21st International Conference on Non-Contact Atomic Force Microscopy 2018 - Porvoo Art Factory, Porvoo, Finland
Duration: 17 Sep 201821 Sep 2018
Conference number: 21
https://ncafm2018.aalto.fi/

Conference

Conference21st International Conference on Non-Contact Atomic Force Microscopy 2018
Abbreviated titleNC-AFM 2018
CountryFinland
CityPorvoo
Period17/09/1821/09/18
Internet address

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    Sîretanu, I., Guo, Y., Mei, B. T., Li, X., Huang, H., Mul, G., & Mugele, F. G. (2018). pH-dependence in facet-selective photo-deposition of metals and metal oxides on semiconductor particles. Poster session presented at 21st International Conference on Non-Contact Atomic Force Microscopy 2018, Porvoo, Finland.