Graphdiyne (C_nH_2n-2) as an “electron transfer bridge” boosting photocatalytic hydrogen evolution over Zn_0.5Co_0.5S/MoS₂ S-scheme heterojunction

In the process of photocatalytic water cracking, the migration rate and utilization rate of photogenerated charges determine the hydrogen evolution performance of the catalyst. In this paper, a carbon isotope superconducting material graphdiyne (GDY) is prepared by mechanical ball milling and introduced into the S-scheme heterojunction Zn_0.5Co_0.5S/MoS₂ inorganic system. In terms of hydrogen evolution kinetics, GDY acts as an electron bridge, not only accelerating the migration of photogenerated carriers but also improving the utilization of photogenerated charges. Morphologically, the large two-dimensional layer provides more loading and anchoring points for Zn_0.5Co_0.5S/MoS₂, which increases the number of active sites. The ternary composite catalyst 20%GDY/Zn_0.5Co_0.5S/Mo₂S (20-GCSM) generates 69.94 μmol of hydrogen (5 h) in triethanolamine solution. It is 2.97 and 1.80 times higher than Zn_0.5Co_0.5S and Zn_0.5Co_0.5S/MoS₂, respectively. After the cyclic experiment, it still has stable hydrogen evolution performance after standing for 24 h (under dark conditions). In addition, the potential mechanism of photocatalytic hydrogen evolution is demonstrated through in-situ X-ray photoelectron spectroscopy. This work provides a reference for further research in the field of introducing carbon materials into photocatalytic systems and improving the utilization of photogenerated charges.