Highly Chiral MoS₂ Flakes With Redox-Active Centers for Spin Selective Water Oxidation

We propose a hydrothermal synthesis route for highly chiral two-dimensional flakes of MoS₂ doped with single nickel atoms (Ni:MoS₂) for spin-controlled water oxidation. Organic enantiomers were added to the reaction mixture as chiral encoders. The resulting MoS₂ material obtained in the 1T phase exhibited wide absorption bands throughout the visible spectrum. Circular dichroism measurements indicated a pronounced chiroptical response at both UV and visible wavelengths. After delamination, the chirality was retained, and the Ni:MoS₂ flakes were subsequently tested for water oxidation under the assumption that the flakes could support chiral-induced spin alignment of the transiting electrons. The chiral-induced spin selectivity (CISS) effect facilitates water oxidation kinetics and tunes the reaction selectivity toward oxygen production. The results of the electrochemical experiments, subsequently confirmed by density functional theory calculations, showed a significant decrease in the water-oxidation offset and onset potentials for the optimal combination of doping and flake chirality. In turn, the CISS effect manifests itself as an apparent suppression of hydrogen peroxide production and enhancement of oxygen production. Our work provides clear evidence of how chiral transition metal dichalcogenides can be used to tune the reaction efficiency and selectivity in energy-related applications.