Selective adsorption of cysteamine molecules on Au/TiO2 boosts visible light-driven photocatalytic hydrogen evolution.

Photocatalytic evolution of hydrogen is becoming a research hotspot because it can help to produce clean energy and reduce environmental pollution. Titanium dioxide (TiO2) and its composites are photocatalysts that are widely used in hydrogen evolution because of their high abundance in nature, low price, and high photo/chemical stability. However, their catalytic performances still need to be further improved, particularly in the visible light spectrum. Herein, visible light-driven photocatalytic evolution of hydrogen on Au/TiO2 nanocomposite is enhanced ∼ 10 folds by selectively functionalizing the nanocomposite with cysteamine molecules. It is revealed that the amine group (-NH2) in cysteamine favors the transfer and separation of photo-generated hot carriers. The rate of hydrogen produced can be further tuned by varying the ionization of the functionalized molecules at different pH values. This work provides a simple, convenient, and effective method that can be used to improve the photocatalytic evolution of hydrogen. This method can also be used for many other nanocatalysts (e.g., Au-MoS2, Au-BiVO4) and catalytic reactions (e.g., carbon dioxide reduction, nitrogen reduction).