Boosting Charge Carrier Separation by Constructing a Dual Metal–Organic Framework-Derived CuO@TiO₂ Heterojunction toward Efficient Visible-Light-Driven Hydrogen Production

The development of photocorrosion-resistant, recoverable, and stable photocatalysts for high-efficiency visible light photocatalytic production of hydrogen is a very urgent task. Herein, a strategy to fabricate CuO@TiO2 heterojunction photocatalysts (CuTi-X) by calcining a dual metal–organic framework at different temperatures has been reported. The results reveal that the CuTi-X catalysts have a regular morphology, highly porous structure, and large specific surface area, providing more contact sites for surface mass transfer in photocatalytic reactions. The TiO2 component is in close contact with the CuO layer uniformly supported on the surface, which facilitates the migration and separation of photogenerated carriers. Optical and electrochemical analyses further confirm that the optimized CuO@TiO2 (CuTi-450) heterojunction exhibits an extended photogenerated carrier lifetime and a reduced mass transfer resistance. CuTi-450 shows a photocatalytic hydrogen evolution rate under visible light irradiation of 1458.1 μmol g–1 h–1, which is 36.2 and 5.5 times higher than that of the single TiO2 (Ti-450) and CuO (Cu-450) components, respectively, and remains stable after four reaction cycles. This work opens an avenue to design stable and efficient oxide heterojunction photocatalysts derived from dual MOFs.