Room temperature exsolution of CdS nanodots on A-site deficient cotton-ball like titanate perovskite nanoparticles for H₂ production under visible light

Exsolution of nanoparticles followed by chemical treatment (“chemistry at a point”) is a very exciting approach to the smart design of functional materials such as visible light active photocatalysts. Unfortunately, the usually utilized thermal reduction approach is not feasible for low melting point metals and compounds such as Cd and CdO. Here a hydrothermal approach to prepare exsolved CdS nanodots on cotton ball-like perovskite supports is described. The titanate-based photocatalyst is synthesized using a hydrothermal process followed by room-temperature sulfidation. The hydrothermal route directs A-site doping of Cd²⁺ via hydroxyl group incorporation in the titanate lattice. Formation of CdS via exsolution provides a high H₂ production mass activity of 3050 µmol g⁻¹ h⁻¹ under visible light with only 5 mol.% Cd doping of the titanate. Moreover, the strong CdS-support interaction offers good cycling stability under UV–vis and visible light irradiation. This is the first report describing the exsolution of CdS nanodots at room temperature and shows its advantages for photocatalytic activity.