Graphene Acting as Surface Phase Junction in Anatase–Graphene–Rutile Heterojunction Photocatalysts for H2 Production from Water Splitting

The construction of heterojunction photocatalysts has received much attention in the field of photocatalytic H2 production from water splitting. The surface phase junction of semiconductors is very important to the activity of heterojunction photocatalysts. In this study, an effective anatase–graphene–rutile heterojunction structure was designed and fabricated by using graphene as the surface phase junction between anatase and rutile particles. Results show that both the anatase/rutile ratio (A/R ratio) and graphene amount represent important influence on H2 production activities of anatase–graphene–rutile heterojunction photocatalysts. Under our experimental condition, the optimum A/R ratio is 7/3 and graphene addition amount is 2 wt %, the corresponding AR7/3–2%G sample has the highest H2 production rate of 1.714 mmol/h. By further experimental study, we think the high H2 production activity of anatase–graphene–rutile heterojunction photocatalyst is from the enhanced charge separation rather than other effect. This work values the expanding of surface phase junction and provides a feasible strategy to develop high-performance photocatalysts by designing and expanding the surface phase junction.