Influence of the Electronic Properties of the Ligand on the Photoelectrochemical Behavior of Au<sub>25</sub> Nanocluster-Sensitized TiO<sub>2</sub> Photoanode
Ye Liu, Ewa Wierzbicka, Andreas Springer, Nicola Pinna, Yu Wang
Abstract
Atomically precise metal nanoclusters (NCs) have recently emerged as a new class of bifunctional (photoactive and catalytically active) photosensitizers in light energy conversion applications. Despite the size and alloy effects of NCs, no effort has been made to elucidate how the protecting ligand affects the photoelectrochemistry of the NC-sensitized photoelectrodes. With a nanoporous TiO2 array as model support, Au25 NCs protected by various thiol-bearing ligands have been used to prepare four different photoanodes. It is revealed that a subtle change of the ligand from an alkanethiol to an aromatic thiol facilitates the charge transfer between the NC and TiO2, which in turn improves the photoelectrochemical performance of the corresponding photoanode by at least 6 times. This new insight highlights the importance of the electronic properties of the ligand on the design of more efficient NC-sensitized photoelectrodes.