Kumar Manish, Basera Pooja, Saini Shikha, Bhattacharya Saswata
Department of Physics, Indian Institute of Technology Delhi, New Delhi, 110016 India.
Sci Rep. 2020 Sep 21;10(1):15372. doi: 10.1038/s41598-020-72195-0.
and are well known materials in the field of photocatalysis due to their exceptional electronic structure, high chemical stability, non-toxicity and low cost. However, owing to the wide band gap, these can be utilized only in the UV region. Thus, it's necessary to expand their optical response in visible region by reducing their band gap through doping with metals, nonmetals or the combination of different elements, while retaining intact the photocatalytic efficiency. We report here, the codoping of a metal and a nonmetal in anatase and for efficient photocatalytic water splitting using hybrid density functional theory and ab initio atomistic thermodynamics. The latter ensures to capture the environmental effect to understand thermodynamic stability of the charged defects at a realistic condition. We have observed that the charged defects are stable in addition to neutral defects in anatase and the codopants act as donor as well as acceptor depending on the nature of doping (p-type or n-type). However, the most stable codopants in mostly act as donor. Our results reveal that despite the response in visible light region, the codoping in and cannot always enhance the photocatalytic activity due to either the formation of recombination centers or the large shift in the conduction band minimum or valence band maximum. Amongst various metal-nonmetal combinations, (i.e. Mn is substituted at Ti site and S is substituted at O site), in anatase and , in are the most potent candidates to enhance the photocatalytic efficiency of anatase and under visible light irradiation.
由于其特殊的电子结构、高化学稳定性、无毒和低成本，[具体物质1]和[具体物质2]是光催化领域中众所周知的材料。然而，由于其宽带隙，这些材料仅能在紫外区域使用。因此，有必要通过掺杂金属、非金属或不同元素的组合来减小其带隙，同时保持光催化效率不变，从而将它们的光学响应扩展到可见光区域。我们在此报告，利用杂化密度泛函理论和从头算原子热力学，在锐钛矿型[具体物质1]和[具体物质2]中进行金属和非金属的共掺杂，以实现高效的光催化水分解。后者确保能够捕捉环境效应，以了解在实际条件下带电缺陷的热力学稳定性。我们观察到，在锐钛矿型[具体物质1]和[具体物质2]中，除了中性缺陷外，带电缺陷也是稳定的，并且根据掺杂性质（p型或n型），共掺杂剂既可以作为施主也可以作为受主。然而，在[具体物质2]中最稳定的共掺杂剂大多作为施主。我们的结果表明，尽管在可见光区域有响应，但由于复合中心的形成或导带最小值或价带最大值的大幅移动，在[具体物质1]和[具体物质2]中的共掺杂并不总能提高光催化活性。在各种金属 - 非金属组合中，锐钛矿型[具体物质1]中的[具体组合1]（即Mn取代Ti位点，S取代O位点）、[具体物质2]中的[具体组合2]以及[具体物质3]中的[具体组合3]是在可见光照射下提高锐钛矿型[具体物质1]和[具体物质2]光催化效率的最有力候选者。
