Heterostructured mesoporous In2O3/Ta2O5 composite photocatalysts for hydrogen evolution: Impacts of In2O3 content and calcination temperature

► 3D interconnected mesoporous In2O3/Ta2O5 were prepared by a sol-gel process. ► A clear heterojunction structure is demonstrated between In2O3 and Ta2O5. ► The calcination temperature (T) influences the mesoporosity and crystallinity. ► The heterojunction characteristic is mainly related to the In2O3 content (x). ► Both T and x play important roles in enhancing the photocatalytic activity.