Ammonia borane assisted mechanochemical boost of electrochemical performance of basal planes of MoS 2 -type materials

The maximization of the number of exposed edges of layered MoS 2 -type transition metal dichalcogenides of general formula MX 2 (M = Mo, W; X = S, Se) is difficult yet meaningful way to improve their electrochemical and electrocatalytic performance. In this work, an all-solid ball milling method for simultaneous introduction of defects and their hybridization through binding of ammonia borane (NH 3 BH 3 ) to defect sites of MX 2 is demonstrated. The milling conditions leads to partial separation and nanosizing of MX 2 layers, simultaneously extensively introducing defects (cracks, vacancies, strains, voids etc.), while the detailed analysis revealed the functionalization of the material by binding of NH 3 BH 3 to defect sites, which results in highly improved electrocatalytic performance of thus obtained composites with respect to MX 2 for hydrogen evolution reaction. The mechanochemical approach thus enables preparation of MoS 2 -type materials with improved, highly tunable activity, potentially relevant for energy conversion and storage.