Synergistic Enhancement of Photocatalytic H2 Evolution over NH2-MIL-125 Modified with Dual Cocatalyst

The construction of efficient photocatalysts for water splitting to enable H₂ evolution is pivotal to alleviate energy issues and environmental concerns. In this work, carbon dots (CDs) were prepared by employing "green solvent" ionic liquids as carbon sources and then combined with Pt/NH₂-MIL-125, resulting in the emergence of a high-efficiency photocatalyst termed CDs-Pt/NH₂-MIL-125 for the first time. This composite photocatalyst exhibited outstanding photocatalytic activity in H₂ production under visible light irradiation. Notably, the H₂ production rate of CDs₁₀₀-Pt/NH₂-MIL-125 reaches up to 951.4 μmol/g/h, which was 3.1 times that of Pt/NH₂-MIL-125. The characterization results indicate that CDs and Pt uniformly dispersed on the surface of NH₂-MIL-125 and fabricated a synergistic compact structure, providing a high BET surface area (985 m² g^-1) and a suitable band gap. Furthermore, the distinctive embeddable-dispersed CDs and Pt, as dual cocatalyst, can harvest light and facilitate the transfer of photogenerated electrons, thereby significantly augmenting the exploitation of visible light. The plausible mechanism of photocatalytic H₂ evolution over the CDs-Pt/NH₂-MIL-125 catalyst was also discussed. This work introduces a promising strategy for designing high-performance CDs-MOFs-based photocatalysts, an innovative step toward achieving efficient photocatalytic water splitting for H₂ production.