Efficient Photoelectrochemical Hydrogen Generation from Water Using a Robust Photocathode Formed by CdTe QDs and Nickel Ion

Design of a novel sensitized NiO photocathode with wide visible light absorption and good stability is of great significance for photoelectrochemical hydrogen evolution. Inspired by recent reports on novel photocatalytic hydrogen evolution systems based on semiconductor quantum dots (QDs) and earth-abundant inorganic metal ion, we demonstrate the fabrication of an effective and stable photocathode by CdTe QDs and nickel ion. This photocathode showed good activity and stability for photocatalytic H2 evolution (10.38 μmol) at a low overpotential of 92 mV, in which the Faradaic efficiency was almost 100% under visible light irradiation for 30 000 s. Characterized by X-ray photoelectron spectroscopy, X-ray powder diffraction and high-resolution transmission electron microscopy, the active site of photocathode in producing hydrogen by water splitting was found to be NiS@QDs. Then a possible mechanism of NiS@QDs for photoelectrochemical hydrogen evolution was proposed.