Facile Synthesis\nof Amorphous NiO/Reduced Graphene\nOxide as a Cocatalyst for Enhanced Dye-Sensitized Photocatalytic H₂ Evolution

Abstract

It is still a challenge to develop efficient catalysts\nfor hydrogen\nevolution reaction (HER) via a low-cost and simple method. Herein,\nwe report an amorphous NiO/reduced graphene oxide (A-NG) composite\nas a cocatalyst for enhanced photocatalytic H₂ evolution\nvia dye sensitization. The A-NG composite is facilely fabricated by\ncalcinating the NiCl₂/GO precursor at a low temperature\nof 250 °C. The detailed characterizations show that amorphous\nNiO presents as tiny nanoparticles highly dispersed on graphene sheets,\nand nickel carbide is formed at the NiO/graphene interface, which\ndemonstrates the strong interaction between Ni and the defective carbon\nof graphene. Compared with crystalline NiO/rGO (C-NG), the A-NG cocatalyst\nshows much enhanced dye-sensitized photocatalytic HER activity because\nthe amorphous NiO nanoparticles can effectively adsorb the dye. As\na result, highly dispersed amorphous NiO accelerates the photoinduced\nelectron transfer from the excited dye to the cocatalyst, namely,\nthe amorphous nickel carbide formed between NiO and rGO. This work\nprovides a low-cost and simple method to develop efficient cocatalysts\nfor photocatalytic H₂ evolution.