Atomic Layered Titanium Sulfide Quantum Dots as Electrocatalysts for Enhanced Hydrogen Evolution Reaction

Abstract The overall electrocatalytic activity toward hydrogen evolution reaction for layered transition metal dichalcogenides is governed by their intrinsic activity, the corresponding density of active sites, and the electron transfer resistance. Here, nanoengineering strategies to scale down both the lateral size and thickness of layered 1T‐TiS 2 powder to quantum dots (QDs) by bath sonication and probing sonication incision are employed. Uniform lateral size of 3–6 nm in the resulting QDs enhances the density of edge sites while the atomic layer thickness (1–2 nm) facilitates the electron transfer from the substrate to the edge sites. The obtained TiS 2 QDs exhibit superior hydrogen evolution reaction activity over TiS 2 nanosheets and MoS 2 QDs prepared by the same method. The turnover frequency of TiS 2 QDs with a small loading of 0.7 ng cm −2 in an optimal deposition on electrode reached ≈2.0 s −1 at an overpotential of −0.2 V versus RHE, several orders of magnitude higher than TiS 2 nanosheets (0.01 s −1 ) and MoS 2 QDs (0.07 s −1 ).