Highly\nEffective Electrochemical Exfoliation of Ultrathin Tantalum Disulfide\nNanosheets for Energy-Efficient Hydrogen Evolution Electrocatalysis

Abstract

Developing\nhighly efficient transition metal dichalcogenide electrocatalysts\nwould be significantly beneficial for the electrocatalytic hydrogen\nevolution reaction (HER) from water splitting. Herein, we reported\nnovel ultrathin tantalum disulfide nanosheets (TaS₂ NSs)\nprepared by electrochemically exfoliating bulk TaS₂ with\nan alternating voltage in an acidic electrolyte. The obtained TaS₂ NS electrocatalyst possessed an ultrathin structure with\na lateral size of 2 μm and a thickness of ∼3 nm. Owing\nto the unique 2D structure, the achieved TaS₂ NSs displayed\nremarkable electrocatalytic activity toward the HER by a small overpotential\nof 197 mV at 10 mA cm^–2 and a small Tafel slope\nof 100 mV dec^–1 in acidic solution, much lower than\nthose of TaS₂ (>547 mV and 216 mV dec^–1, respectively) and other reported TaS₂-based HER electrocatalysts.\nFurthermore, highly efficient full water splitting could be realized\nwith two electrodes in which TaS₂ NSs acted as the cathode\nwhile Ir/C served as the anode, with help of two AA size batteries\nor solar cells. By replacing the oxygen evolution reaction with the\nurea oxidation reaction (UOR), bifunctional TaS₂ NSs enabled\nan energy-effective HER process in the cathode and UOR process in\nthe anode with decreased applied potential.