Boosting photocatalytic hydrogen generation of cadmium telluride colloidal quantum dots by nickel ion doping

Splitting water into hydrogen (H₂) with sunlight is an appealing approach towards alleviating the fossil fuel crisis. However, as one of the most promising light harvesters, colloidal quantum dots (QDs) generally exhibit low photocatalytic activity towards H₂ evolution because of the lack of catalytic sites on their surface. Many researchers have focused on activating QDs by anchoring metal complexes on their surface, in which the photoexcited electrons may transfer from the QDs to the metal centres via the organic ligands. These bulky organic ligands usually have poor electrical conductivity and chemical instability, thereby causing high charge recombination and low durability in these QDs/metal complex catalysts. To address these issues, we herein report the doping of cadmium telluride (CdTe) QDs with nickel ions (Ni²⁺), achieving a remarkable H₂ generation rate without the use of co-catalysts. The formation rate of H₂ exceeded 27.3 mmol/g/h under visible light irradiation, which is approximately 110-fold higher than that of pristine CdTe QDs. This doping strategy provides a versatile route to reduce protons to H₂ with a turnover number of 13,650 in terms of Ni and confer superior durability on the CdTe QDs.