Carbon dots enhance the stability of CdS for visible-light-driven overall water splitting

Abstract

Cadmium sulfide (CdS) has long time been one of the most promising inorganic photocatalysts for hydrogen production driven by visible light. However, the photocorrosion of CdS is the most serious problem which constrains its development. Here, we report the design and fabrication of a carbon dots-cadmium sulfide (CDs-CdS) nanocomposite, showing significant photocatalytic water splitting properties with impressive stability without requirement for any sacrificial agents or cocatalysts. The highest hydrogen production rate was obtained for about 2.55μmolh−1, with an oxygen evolution rate for about 0.52μmolh−1, when the concentration of CDs in the sample is 0.03gCDs/gcatalyst. Even the produced H2 and O2 are not equal to the stoichiometric ratio of 2:1 (H2:O2), the CDs-CdS nanocomposite shows greater stability (8-time repetitive catalytic experiments) than the CdS catalysts reported up to now (without sacrificial agents or cocatalysts). It is also inspiring that when we increased the concentration of CDs in the catalysts, the produced H2 and O2 were gradually adjusted to meet the stoichiometric ratio of 2:1 in spite of low hydrogen production rate (0.13μmolh−1).