Fan Yingcai, Wang Junru, Zhao Mingwen
School of Physics and State Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong, China.
Nanoscale. 2019 Aug 8;11(31):14836-14843. doi: 10.1039/c9nr03469b.
Spontaneous full photocatalytic water splitting into hydrogen and oxygen under visible light irradiation without the need for sacrificial agents is a challenging task, because suitable band gaps, low overpotentials for both half-reactions and spatially-separated catalytic sites should be fulfilled simultaneously in a photocatalytic system. Here, we propose a promising strategy to achieve this goal by constructing van der Waals (vdW) heterostructures of two-dimensional (2D) materials. Using first-principles calculations, we predict two promising photocatalysts, MoSe2/SnSe2 and WSe2/SnSe2 heterostructures, with the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) taking place separately on the MoSe2 (WSe2) and SnSe2 layers. More excitingly, the Se-vacancy of the MoSe2 (WSe2) monolayer effectively lowers the HER overpotential, making the catalytic reactions occur spontaneously under the potentials solely provided by the photo-generated electrons and holes in pure water. The unique band alignment of these hetero-structured photocatalysts leads to high solar-to-hydrogen (STH) energy conversion efficiencies up to 10.5%, which is quite promising for commercial applications. This work opens up an avenue for the design of highly-efficient photocatalysts for full water splitting.
在可见光照射下，无需牺牲剂就能自发地将水完全光催化分解为氢气和氧气是一项具有挑战性的任务，因为在光催化体系中需要同时满足合适的带隙、两个半反应的低过电位以及空间分离的催化位点。在此，我们提出一种有前景的策略，通过构建二维（2D）材料的范德华（vdW）异质结构来实现这一目标。利用第一性原理计算，我们预测了两种有前景的光催化剂，即MoSe2/SnSe2和WSe2/SnSe2异质结构，析氢反应（HER）和析氧反应（OER）分别在MoSe2（WSe2）层和SnSe2层上发生。更令人兴奋的是，MoSe2（WSe2）单层的硒空位有效地降低了HER过电位，使得催化反应在仅由纯水中光生电子和空穴提供的电位下自发发生。这些异质结构光催化剂独特的能带排列导致高达10.5%的高太阳能到氢能（STH）能量转换效率，这对于商业应用非常有前景。这项工作为设计用于全水分解的高效光催化剂开辟了一条途径。
