Novel visible-light driven Mn0.8Cd0.2S/g-C3N4 composites: Preparation and efficient photocatalytic hydrogen production from water without noble metals

A series of novel visible light-responsive Mn 0.8 Cd 0.2 S/g-C 3 N 4 hybrid materials with different g-C 3 N 4 contents were synthesized via a facile hydrothermal method. The obtained Mn 0.8 Cd 0.2 S/g-C 3 N 4 composites displayed highly efficient photocatalytic activities for H 2 evolution from aqueous solutions containing sacrificial reagents (Na 2 S and Na 2 SO 3 ) under visible light ( λ   >   420   nm) even without noble metal co-catalysts. The highest H 2 evolution rate of 4.0   mmol   h −1   g −1 (with an apparent quantum efficiency of 4.1% at 420   nm) was achieved on the Mn 0.8 Cd 0.2 S/g-C 3 N 4 (10   wt%) sample, which was about 3.40 times higher than that of pure Mn 0.8 Cd 0.2 S. The enhanced photocatalytic activity of Mn 0.8 Cd 0.2 S/g-C 3 N 4 composites should be attributed to the well-matched band structure and intimate contact interfaces between Mn 0.8 Cd 0.2 S and g-C 3 N 4 , which led to the effective transfer and separation of the photogenerated charge carriers. In addition, the Mn 0.8 Cd 0.2 S/g-C 3 N 4 photocatalysts showed good stability during the photocatalytic water splitting to hydrogen under visible light. A possible mechanism of the enhanced photocatalytic activity of Mn 0.8 Cd 0.2 S/g-C 3 N 4 was also proposed.