Theoretical investigation on RuO2 nanoclusters adsorbed on TiO2 rutile (110) and anatase (101) surfaces

It is fundamental to uncover adsorption properties of metal oxide nanoclusters as cocatalysts on semiconductor surface and charge transfer mechanisms at the interface to understand experimentally observed improvement of photocatalytic activity. This work presents first-principle calculation on RuO2 nanoclusters as an example of cocatalysts adsorbed at rutile TiO2 (110) and anatase TiO2 (101) surfaces, determines the most stable adsorption configurations and elucidates the binding nature of ruthenium oxide clusters on TiO2 surfaces. Our results demonstrate that, for the same cluster size, adsorption energy of RuO2 cluster on rutile surface is larger than that on anatase surface due to more interfacial bonds formed between cluster and surface. The adsorption of RuO2 clusters on rutile (110) surface rather than anatase (101) surface brings noticeable contributions of cluster-related states in the top of valence bands. Upon light irradiation, electron transfer from ruthenium oxide cluster to surface increases the possibility of spatially separating photoinduced electron and hole, which is beneficial to the enhancement of photocatalytic activity. The present study may be helpful for understanding the enhanced photocatalytic activity by loading appropriate cocatalysts on the surface of semiconductor.