University of Science and Technology of China
As an ultimate clean energy, hydrogen produced by photocatalytic water splitting using solar energy plays an important role in solving energy and environmental problems. The key of solar hydrogen production is to develop photocatalysts active under visible light. Traditional photocatalysts are discovered in metal oxides, sulfides and nitrides with d0 or d10 transition metal cations. Unfortunately, most of these catalysts are active only under UV irradiation, while others absorbing visible light either suffer stability problems during the reaction process, such as photocorrosion for metal sulﬁde photocatalyst, or the quantum yield is too low for practical use. Photocatalysts with sufficiently high productivity are not found yet. Searching for new efficient photocatalysts both from theoretical and experimental aspects is urgently needed.
Metal-free photocatalysts may have the advantage of non-toxicity and good processability, and are gradually becoming an important catalyst developing. In this report, based on first principles calculations, we propose two visible light driven metal-free photocatalysts for water splitting by chemical functionazation of BN sheet and germanane, that is, half-hydrogenated BN nanosheet (H-BN) with a band gap of 2.24eV and fluorine substituted germanane (GeH2-xFx) with a gap of 1.45eV. We find that the conditions for water splitting are well satisfied and the photocatalysts possess a good electron-hole separation.