Synthesis and Characterization of Two Functional Complexes Based on 2-Methyldipyrido[3,2-f:2′,3′-h]quinoxaline as Co-catalysts and Their Enhancement on Photocatalytic H 2 Production Activity of g-C 3 N 4

Hydrogen as a new energy source, it can be made by photocatalytic technology. However, the photocatalyst is the key to the efficient decomposition of water to produce hydrogen. Functional complexes are porous materials with high crystallinity, which have the characteristics of both organic and inorganic materials. For this reason, two complexes [Mn 3 (Medpq) 2 (CIN) 6 ]·H 2 O (1) and [Cd 3 (Medpq) 2 (CIN) 2 (Ac) 4 ] (2) (HCIN = cinnamic acid, Medpq = 2-methyldipyrido[3,2-f:2′,3′-h]quinoxaline) were synthesized by a hydrothermal process. Combined with the unique electronic structure and group of the complex and the unique semiconductor energy band structure and excellent chemical stability of g-C 3 N 4 , the complex/g-C 3 N 4 composite materials were constructed to solve the defect of low utilization rate of light energy and improve quantum efficiency in the internal structure. The experiment proved that complex 1/g-C 3 N 4 photocatalytic rates of hydrogen production 715.8 μmol h −1 g −1 , and complex 2 photocatalytic rates of hydrogen production 1622.9 μmol h −1 g −1 , about double and fourfold that of pure g-C 3 N 4 (407.6 μmol h −1 g −1 ) consequently, high-performance of the hydrogen production from water decomposition was realized. Graphical Abstract The two functional complexes [Mn 3 (Medpq) 2 (CIN) 6 ]·H 2 O (1) and [Cd 3 (Medpq) 2 (CIN) 2 (Ac) 4 ] (2) have the characteristics of both organic and inorganic materials and significantly enhance visible-light photocatalytic hydrogen evolution.