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<p>Mn<sub>0.5</sub>Cd<sub>0.5</sub>S (MCS) is widely used in photocatalytic hydrogen production via water splitting. However, its inherent drawbacks, including low separation efficiency of photogenerated electron–hole pairs, poor stability, and severe photocorrosion, limit hydrogen production efficiency. In this study, carbon quantum dots (CQDs) were synthesized using alkaline lignin as the carbon source and were loaded onto the surface of MCS via ultrasonic-assisted treatment to construct CQDs/MCS composite photocatalyst. Characterization results revealed that the introduction of CQDs did not alter the crystal structure of MCS but effectively broadened its light absorption range, leading to a red shift of the absorption edge and a narrowed band gap, as well as reduced charge transfer resistance and hydrogen evolution overpotential. The CQDs/MCS composite photocatalyst with the addition of 15&#xa0;mL CQDs solution exhibited the optimal photocatalytic performance, with a hydrogen evolution rate of 13.11&#xa0;mmol g<sup>−1</sup> h<sup>−1</sup>, which was 1.33 times higher than that of pure MCS. Moreover, the composite showed excellent recyclability. The enhanced hydrogen evolution performance of CQDs/MCS can be attributed to the fact that CQDs can capture photogenerated electrons and accelerate the separation of electron–hole pairs. In conjunction with the hole consumption by sacrificial agents, the CQDs/MCS composite achieved significantly enhanced photocatalytic hydrogen evolution performance.</p>

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Preparation of CQDs/Mn0.5Cd0.5S composite photocatalyst and its photocatalytic hydrogen evolution study

  • 期刊论文

  • 发表日期：

    2026年7月2日

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  • Hengyu Ai,
  • Fanqi Meng,
  • Shanshan Wang,
  • Oxana P. Taran,
  • Fubao Sun,
  • Hong Yan

摘要

Mn0.5Cd0.5S (MCS) is widely used in photocatalytic hydrogen production via water splitting. However, its inherent drawbacks, including low separation efficiency of photogenerated electron–hole pairs, poor stability, and severe photocorrosion, limit hydrogen production efficiency. In this study, carbon quantum dots (CQDs) were synthesized using alkaline lignin as the carbon source and were loaded onto the surface of MCS via ultrasonic-assisted treatment to construct CQDs/MCS composite photocatalyst. Characterization results revealed that the introduction of CQDs did not alter the crystal structure of MCS but effectively broadened its light absorption range, leading to a red shift of the absorption edge and a narrowed band gap, as well as reduced charge transfer resistance and hydrogen evolution overpotential. The CQDs/MCS composite photocatalyst with the addition of 15 mL CQDs solution exhibited the optimal photocatalytic performance, with a hydrogen evolution rate of 13.11 mmol g−1 h−1, which was 1.33 times higher than that of pure MCS. Moreover, the composite showed excellent recyclability. The enhanced hydrogen evolution performance of CQDs/MCS can be attributed to the fact that CQDs can capture photogenerated electrons and accelerate the separation of electron–hole pairs. In conjunction with the hole consumption by sacrificial agents, the CQDs/MCS composite achieved significantly enhanced photocatalytic hydrogen evolution performance.