Dudziak Szymon, Karczewski Jakub, Ostrowski Adam, Trykowski Grzegorz, Nikiforow Kostiantyn, Zielińska-Jurek Anna
Department of Process Engineering and Chemical Technology, Gdansk University of Technology, G. Narutowicza 11/12, 80-273Gdansk, Poland.
Institute of Materials Science and Nanotechnology, Gdansk University of Technology, G. Narutowicza 11/12, 80-273Gdansk, Poland.
ACS Mater Au. 2024 Mar 26;4(4):436-449. doi: 10.1021/acsmaterialsau.4c00008. eCollection 2024 Jul 10.
The present study highlights the importance of the net density of charge carriers at the ground state on photocatalytic activity of the faceted particles, which can be seen as a highly underexplored problem. To investigate it in detail, we have systematically doped {1 0 1} enclosed anatase nanoparticles with Gd ions to manipulate the charge carrier concentration. Furthermore, control experiments using an analogical Nb doped sample were performed to discuss photocatalytic activity in the increased range of free electrons. Overall results showed significant enhancement of phenol degradation rate and coumarin hydroxylation, together with an increase of the designed Gd/Ti ratio up to 0.5 at. %. Simultaneously, the mineralization efficiency, measured as a TOC reduction, was controlled between the samples. The observed activity enhancement is connected with the controlled decrease of the donor state density within the materials, being the net effect of the spontaneously present defects and introduced dopants, witch reduce hydroxylation and the hole trapping ability of the {1 0 1} facets. This allows to fine-tune multi-/single-electron processes occurring over the prepared samples, leading to clear activity maxima for 4-nitrophenol reduction, HO generation, and ·OH formation observed for different donor densities. The optimized material exceeds the activity of the TiO P25 for phenol degradation by 52% (377% after surface normalization), showing its suitable design for water treatment. These results present a promising approach to boost photocatalyst activity as the combined result of the exposed crystal facet and dopant-optimized density of ground-state charge carriers.
本研究强调了基态电荷载流子的净密度对多面体颗粒光催化活性的重要性，这一问题在很大程度上尚未得到充分探索。为了详细研究这一问题，我们系统地用Gd离子对{1 0 1}面封闭的锐钛矿纳米颗粒进行了掺杂，以控制电荷载流子浓度。此外，还进行了使用类似的Nb掺杂样品的对照实验，以讨论在自由电子增加范围内的光催化活性。总体结果表明，苯酚降解率和香豆素羟基化显著提高，同时设计的Gd/Ti比增加到0.5原子%。同时，在各样品之间控制了以TOC降低衡量的矿化效率。观察到的活性增强与材料中施主态密度的受控降低有关，这是自发存在的缺陷和引入的掺杂剂的综合效应，它们降低了{1 0 1}面的羟基化和空穴捕获能力。这使得可以对制备样品上发生的多电子/单电子过程进行微调，从而在不同施主密度下观察到4-硝基苯酚还原、HO生成和·OH形成的明显活性最大值。优化后的材料在苯酚降解方面的活性比TiO P25高出52%（表面归一化后为377%），表明其在水处理方面的合适设计。这些结果提出了一种有前景的方法来提高光催化剂的活性，这是暴露晶面和掺杂剂优化的基态电荷载流子密度共同作用的结果。
