Engineering the TiO 2 –Graphene Interface to Enhance Photocatalytic H 2 Production

In this work, TiO 2 –graphene nanocomposites are synthesized with tunable TiO 2 crystal facets ({100}, {101}, and {001} facets) through an anion‐assisted method. These three TiO 2 –graphene nanocomposites have similar particle sizes and surface areas; the only difference between them is the crystal facet exposed in TiO 2 nanocrystals. UV/Vis spectra show that band structures of TiO 2 nanocrystals and TiO 2 –graphene nanocomposites are dependent on the crystal facets. Time‐resolved photoluminescence spectra suggest that the charge‐transfer rate between {100} facets and graphene is approximately 1.4 times of that between {001} facets and graphene. Photoelectrochemical measurements also confirm that the charge‐separation efficiency between TiO 2 and graphene is greatly dependent on the crystal facets. X‐ray photoelectron spectroscopy reveals that TiC bonds are formed between {100} facets and graphene, while {101} facets and {001} facets are connected with graphene mainly through TiOC bonds. With TiC bonds between TiO 2 and graphene, TiO 2 ‐100‐G shows the fastest charge‐transfer rate, leading to higher activity in photocatalytic H 2 production from methanol solution. TiO 2 ‐101‐G with more reductive electrons and medium interfacial charge‐transfer rate also shows good H 2 evolution rate. As a result of its disadvantageous electronic structure and interfacial connections, TiO 2 ‐001‐G shows the lowest H 2 evolution rate. These results suggest that engineering the structures of the TiO 2 –graphene interface can be an effective strategy to achieve excellent photocatalytic performances.