Encapsulating N‑doped graphite carbon in MoO₂ as a novel cocatalyst for boosting photocatalytic hydrogen evolution

Generally, it is important to ameliorate the co-catalyst used in photocatalytic hydrogen evolution reactions (PHERs) to achieve efficient transfer and separation of photogenerated carriers, decrease the surface reaction energy barrier, and hence improve the photocatalytic activity. In this study, N-doped graphite carbon (GC) was introduced in situ to MoO₂ to ensure the presence of well-dispersed active sites, lower the overpotential of hydrogen evolution, and further achieve high conductivity. Then, the MoO₂/GC composite obtained was used as a co-catalyst of ZnIn₂S₄ (ZIS) in a PHER, resulting in a great improvement in the photocatalytic activity. Given the metallicity and large work function of MoO₂/GC, a Schottky interface can form between MoO₂/GC and ZIS, which accelerates the transmission of photogenerated electrons. As a result, the separation efficiency of photogenerated carriers improves, whereas the surface overpotential of PHERs clearly decreases for ZIS. This study proposes a new idea for exploiting efficient co-catalysts and promotes the wide and heavy use of carbon materials in the field of solar energy conversion.