Hierarchical porous NiO as a noble‐metal‐free cocatalyst for enhanced photocatalytic H 2 production of nitrogen‐deficient g‐C 3 N 4

Graphitic carbon nitride with nitrogen vacancies (NV‐g‐C 3 N 4 ) as a photocatalyst has been studied in solar‐driven energy conversion. However, expensive and rare noble metal co‐catalysts such as Pt or Pd are required in the photocatalytic H 2 evolution. Consequently, the exploration of low‐cost and high‐performance co‐catalysts to replace expensive and rare noble metals has received more and more attention. Herein, a novel hierarchical porous NiO anchored on NV‐g‐C 3 N 4 is successfully fabricated. The NV‐g‐C 3 N 4 /NiO photocatalysts exhibited outstanding H 2 evolution rate under visible light irradiation in absence of noble metal co‐catalysts. The optimized NV‐g‐C 3 N 4 /NiO (the mass ratio of NiO is ~ 1.7%) achieved a maximum H 2 evolution rate of 170.60 μmol·g −1 ·h −1 , exhibiting ∼ 8.3‐fold enhancement as compared to that of NV‐g‐C 3 N 4 . NiO as co‐catalyst provided more active sites for photocatalytic H 2 evolution. Moreover, on the interface of NV‐g‐C 3 N 4 /NiO, an interface electric field is formed between NiO and host nitrogen‐vacated g‐C 3 N 4 , facilitating the transfer of the photogenerated electrons from NV‐g‐C 3 N 4 to NiO co‐catalyst, resulting in significantly promoted migration and separation efficiency of the photogenerated charge carriers.