Bis(aminothiolato)nickel nanosheet as a redox switch for conductivity and an electrocatalyst for the hydrogen evolution reaction

A π-conjugated coordination nanosheet comprising bis(aminothiolato)nickel (<b>NiAT</b>) moieties was synthesized by the reaction of Ni(acac)₂ with 1,3,5-triaminobenzene-2,4,6-trithiol at liquid-liquid and gas-liquid interfaces. The sheet thickness could be controlled down to a single layer (0.6 nm). Selected area electron diffraction and grazing incidence X-ray diffraction analyses indicated the formation of a flat crystalline sheet with a kagome lattice stacked in a staggered alignment. <b>NiAT</b> was reversibly interconverted to a bis(iminothiolato)nickel (<b>NiIT</b>) nanosheet by the chemical 2H⁺-2e^- reaction, which was accompanied by a drastic change in electrical conductivity from 3 × 10^-6 to 1 × 10^-1 S cm^-1. This change in conductivity was explained by the difference in band structures between <b>NiAT</b> and <b>NiIT</b>. <b>NiAT</b> acted as an efficient electrocatalyst for the hydrogen evolution reaction, showing strong acid durability and an onset overpotential of -0.15 V.