Molecular Foundry, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
Nano Lett. 2012 Jan 11;12(1):383-8. doi: 10.1021/nl203669k. Epub 2011 Dec 22.
Semiconductor photocatalysts capable of broadband solar photon absorption may be nonetheless precluded from use in driving water splitting and other solar-to-fuel related reactions due to unfavorable band edge energy alignment. Using first-principles density functional theory and beyond, we calculate the electronic structure of passivated CdSe surfaces and explore the opportunity to tune band edge energies of this and related semiconductors via electrostatic dipoles associated with chemisorbed ligands. We predict substantial shifts in band edge energies originating from both the induced dipole at the ligand/CdSe interface and the intrinsic dipole of the ligand. Building on important induced dipole contributions, we further show that, by changing the size and orientation of the ligand's intrinsic dipole moment via functionalization, we can control the direction and magnitude of the shifts of CdSe electronic levels. Our calculations suggest a general strategy for enabling new active semiconductor photocatalysts with both optimal opto-electronic, and photo- and electrochemical properties.
半导体光催化剂虽然能够宽带太阳光子吸收，但由于不利的能带边缘能量排列，可能仍无法用于驱动水分解和其他太阳能到燃料相关反应。使用第一性原理密度泛函理论和超越，我们计算了钝化 CdSe 表面的电子结构，并探索了通过与化学吸附配体相关的静电偶极子来调整这种半导体和相关半导体的能带边缘能量的机会。我们预测了源自配体/CdSe 界面处诱导偶极子和配体固有偶极子的能带边缘能量的大幅度变化。基于重要的诱导偶极子贡献，我们进一步表明，通过官能化改变配体固有偶极子的大小和方向，我们可以控制 CdSe 电子能级的偏移方向和幅度。我们的计算表明了一种通用策略，可以实现具有最佳光电、光和电化学性能的新型活性半导体光催化剂。
