Enhanced photocatalytic hydrogen evolution over graphitic carbon nitride modified with Ti-activated mesoporous silica

• Graphitic carbon nitride modified with Ti-activated mesoporous silica.
• Ti-MCM-41/g-C3N4 showed superior photocatalytic activity under visible light.
• Electrons in g-C3N4 can be easily transferred to the [Ti4+-O2−] active centers in Ti-MCM-41.
• Photoinduced charge carriers were efficiently separated between g-C3N4 and Ti-MCM-41.

In this study, it was demonstrated that the visible light photocatalytic hydrogen evolution performance of g-C3N4 could be enhanced when g-C3N4 was loaded onto the MCM-41 mesoporous silica, and the photocatalytic activity of obtained MCM-41/g-C3N4 was 1.2 times as high as that of pure g-C3N4. This is mainly because the high dispersion of g-C3N4 on MCM-41 leads to the improved separation efficiency of electrons and holes photoexcited in g-C3N4. By introducing Ti into the MCM-41 framework structure to create [Ti4+-O2−] active centers, the visible light driven photocatalytic activity of the obtained Ti-MCM-41/g-C3N4 was further increased, with hydrogen production rate reaching 80.76 μmol h−1 g−1, which was 1.6 times as high as that of pure g-C3N4. In the Ti-MCM-41/g-C3N4 composite photocatalysts, the photo-generated electrons in the conduction band of g-C3N4 can be easily transferred to the [Ti4+-O2−] active centers in Ti-MCM-41 framework, hence, the separation efficiency of the photo-generated charge carriers was further improved, achieving higher photocatalytic activity of Ti-MCM-41/g-C3N4 than MCM-41/g-C3N4 as well as pure g-C3N4.

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