Lawrence Berkeley National Laboratory

Herein, we report the synthesis of two-dimensional Ta₂Se₂C (2D-Ta₂Se₂C) nanosheets using electrochemical lithiation in multilayer Ta₂Se₂C followed by sonication in deionized water. Multilayer Ta₂Se₂C was obtained via solid-state synthesis of Fe_xTa₂Se₂C followed by chemical etching of Fe. 2D-Ta₂Se₂C exhibited promising electrocatalytic activity for the hydrogen evolution reaction from water compared to multilayer Ta₂Se₂C and 2D-TaSe₂. 2D-Ta₂Se₂C showed an overpotential at 10 mA·cm^-2 (η₁₀) of 264 mV, a Tafel slope of 91 mV·dec^-1, and an electrochemically active surface area of 17.61 m_ECSA²·g_catalyst^-1. The high performance could be attributed to the large surface area of single sheets which hence maximizes the number of exposed catalytic sites and increased density of vacancies, observed with transmission electron microscopy, during synthesis and processing.