Engineering MoTe2 and Janus SeMoTe nanosheet structures: First-principles roadmap and practical uses in hydrogen evolution reactions and symmetric supercapacitors

Recent advancements in van der Waals-bonded atomically layered structures have tremendously shaped the possibilities of exploring novel materials and physical phenomena for practical modern applications. The astonishing physicochemical characteristics inspired by the Janus transition-metal dichalcogenides (TMDs) of SeMoTe owing to their asymmetric atomic arrangements were deliberately chosen for study by first-principles calculations with an elaborate comparison of their paternal MoSe2 and MoTe2 structures. The experimental synthesis was made by a cost-effective one-pot reaction methodology to engineer MoTe2 and SeMoTe alloy nanosheet structures. For the water-splitting hydrogen evolution reaction, the SeMoTe alloy nanosheet structures evolved low overpotentials and Tafel slopes in alkaline and acidic media, which proved their persistent atomic arrangements regardless of the pH. To extend their uses, symmetric capacitors were made using MoSe2, MoTe2, and SeMoTe active electrodes, and found their high specific energy of 41.3 W h kg−1 at a specific power of 4.0 kW kg−1 with 367 F g−1 capacitance at a current density of 1.0 A g−1 for the Janus SeMoTe nanosheet structure. The observed results not only discover the incredible potential of Janus SeMoTe nanosheets for green energy production and symmetric storage devices but also facilitate novel phenomena to engineer asymmetrically stretched TMD structures for future smart applications.