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Core–Shell Double Doping of Zn and Ca on β-Ga2O3 Photocatalysts for Remarkable Water Splitting
ACS Catalysis ( IF 12.9 ) Pub Date : 2021-01-28 , DOI: 10.1021/acscatal.0c05104
Akira Yamakata 1 , Junie Jhon M. Vequizo 1 , Takafumi Ogawa 2 , Kosaku Kato 1 , Shoya Tsuboi 1 , Naohiro Furutani 3 , Masahiro Ohtsuka 4 , Shunsuke Muto 4 , Akihide Kuwabara 2 , Yoshihisa Sakata 3
Affiliation  

Photocatalytic water splitting reaction attracts considerable attention owing to their potential application to generate H2 gas from H2O by using solar energy. However, further activity enhancement is indispensable for industrial use. Various approaches have been adopted to improve its activity; however, as these defects and impurities are the main obstacles that reduce quantum efficiency (QE), the fabrication of fine crystals with low defects and impurities has been essential for activity improvement. Here, we found that Zn and Ca core–shell double doping in polycrystalline β-Ga2O3 photocatalysts is very effective to enhance the photocatalytic activity, and QE reaches 71% under 254 nm illumination. Time-resolved IR absorption spectroscopy and first-principles calculations revealed that Zn and Ca create shallow mid-gap states, and electron trapping at these states prevent the electron–hole recombination. STEM–EDS mapping analysis demonstrate that Ca is doped uniformly in the bulk, but Zn is doped on the surface. These findings herein indicate that the induced concentration gradient of the dopants effectively inhibit the recombination in the bulk and at the surface and assist the diffusion of trapped electrons from the bulk to the surface, thereby accelerating reactions at the surface. These cooperative effects provide an attractive strategy to enhance the photocatalytic activity, which can be applied to many other photocatalysts including rough polycrystalline powders. This method requires neither the fabrication of fine single crystals nor the precise control of the co-catalyst loading.

中文翻译:

Zn和Ca对核-壳双掺杂的β-Ga 2个ö 3光催化剂为显着的分解水

光催化水分解反应由于其潜在的用途,可以利用太阳能从H 2 O生成H 2气体而引起了极大的关注。但是,对于工业用途而言,进一步增强活性是必不可少的。已经采取了各种方法来改善其活动;然而,由于这些缺陷和杂质是降低量子效率(QE)的主要障碍,因此,制造具有低缺陷和杂质的微晶对于提高活性至关重要。在此,我们发现在多晶中Zn和Ca核壳双掺杂的β-Ga 2 ö 3光催化剂对增强光催化活性非常有效,在254 nm的光照下QE达到71%。时间分辨红外吸收光谱和第一性原理计算表明,Zn和Ca产生浅的中间能隙状态,并且在这些状态下的电子俘获阻止了电子-空穴的复合。STEM-EDS映射分析表明,Ca在整体中均匀掺杂,而Zn在表面掺杂。本文中的这些发现表明,所诱导的掺杂剂的浓度梯度有效地抑制了主体中和在表面处的重组,并且有助于捕获的电子从主体向表面的扩散,从而加速了表面处的反应。这些协同效应提供了一种有吸引力的策略来增强光催化活性,可以应用于许多其他光催化剂,包括粗糙的多晶粉末。该方法既不需要精细的单晶制造,也不需要精确控制助催化剂的负载。
更新日期:2021-02-19
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