CoSe₂ Embedded in C₃N₄: An Efficient Photocathode for Photoelectrochemical Water Splitting

An efficient H 2 evolution catalyst is developed by grafting CoSe 2 nanorods into C 3 N 4 nanosheets. The as-obtained C 3 N 4 –CoSe 2 heterostructure can show excellent performance in H 2 evolution with outstanding durability. To generate phatocathode for photoelectrochemical water splitting CoSe 2 grafted in C 3 N 4 was decorated on the top of p-Si microwires (MWs). p-Si/C 3 N 4 –CoSe 2 heterostructure can work as an efficient photocathode material for solar H 2 production in PEC water splitting. In 0.5 M H 2 SO 4, p-Si/C 3 N 4 –CoSe 2 can afford photocurrent density −4.89 mA/cm 2 at “0” V vs RHE and it can efficiently work for 3.5 h under visible light. Superior activity of C 3 N 4 –CoSe 2 compared to CoSe 2 toward H 2 evolution is explained with the help of impedance spectroscopy.