Effects of a Ni cocatalyst on the photocatalytic hydrogen evolution reaction of anatase TiO2 by first-principles calculations,New Journal of Chemistry

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Effects of a Ni cocatalyst on the photocatalytic hydrogen evolution reaction of anatase TiO2 by first-principles calculations
New Journal of Chemistry ( IF 2.7 ) Pub Date : 2020/03/09 , DOI: 10.1039/c9nj06398f
Ping Zhuang _{1,

2,

3,

4} , Haiying Yue _{1,

2,

3,

4} , Hao Dong _{1,

2,

3,

4} , Xin Zhou _{4,

5,

6,

7}

Affiliation

TiO₂ is a promising photocatalyst for overall water splitting, and its low efficiency for the hydrogen evolution reaction (HER) can be improved by loading proper cocatalysts. Accordingly, to explore the working mechanism of Ni/TiO₂ photocatalysts in the HER, we performed in-depth first-principles calculations. It was found that it is more difficult for the Ni_n cluster to undergo aggregation on the TiO₂(001) surface than the TiO₂(101) surface. The structural difference between these two surfaces determines the above-mentioned property. The adsorption of the Ni_n cluster on the TiO₂ surface is beneficial for the separation of photogenerated charges by introducing mid-gap states into the band gap and elevating the Fermi level to a higher energy region, which is favorable for the HER. An electrochemical computational method was applied to investigate the process of producing hydrogen. Our results indicate that the active site of HER in Ni_n/TiO₂ composites is the O_2c atoms binding or near to the Ni_n cluster. Thus, loading Ni_n clusters remarkably decreases the Gibbs free energy of the HER compared with clean surfaces. Our study reveals the growth behavior of the Ni cocatalyst on the anatase TiO₂ surfaces and presents a reasonable explanation for the experimental improvement in the photocatalytic activity of TiO₂ for HER upon introducing Ni cocatalysts.

中文翻译：

镍助催化剂对锐钛矿型锐钛矿型TiO2光催化析氢反应的影响。

TiO ₂是用于整个水分解的有前途的光催化剂，并且通过加入适当的助催化剂可以改善其对氢析出反应（HER）的低效率。因此，为了探索Ni / TiO ₂光催化剂在HER中的工作机理，我们进行了深入的第一性原理计算。发现Ni _n团簇比TiO ₂（101）表面更难以在TiO ₂（001）表面上发生聚集。这两个表面之间的结构差异决定了上述特性。Ni _n团簇在TiO ₂上的吸附通过将中带隙态引入带隙并将费米能级提高到较高的能量区域，表面有利于光生电荷的分离，这对HER是有利的。采用电化学计算方法研究了制氢过程。我们的结果表明，HER在Ni _n / TiO ₂复合材料中的活性中心是结合或靠近Ni _n团簇的O _2c原子。因此，与干净的表面相比，负载Ni _n团簇显着降低了HER的吉布斯自由能。我们的研究揭示了Ni助催化剂在锐钛矿TiO ₂上的生长行为并提出了合理的解释，说明引入Ni助催化剂后TiO ₂对HER的光催化活性的实验改进。

更新日期：2020-04-06

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