Synthesis of two-dimensional TaB2 and its application in electrocatalytic water splitting

Abstract

Diborides of transition metals (IV–VIB) possess a layered structure, and their exfoliation into two-dimensional (2D) materials has been attempted; however, this is challenging due to the strength of the metal–boron bonds between the layers. Herein, TaB_2−zI_x 2D materials were prepared via a facile two-step method. The TaB_2−zI_x precursors were synthesized via chemical vapor transportation at 750 °C for 12 h and then exfoliated into 2D TaB_2−zI_x in n-butyllithium hexane solution. The results demonstrated that the typical nanosheet was about 0.891 nm thick (approaching a single layer) and 830 nm wide. Density functional theory calculation indicated that the single-layer nanosheet still possessed metallic behaviour. The NiFeLDH (layered double hydroxide)/2D TaB_2−zI_x/NF (nickel foam)-45 composite electrodes displayed an enhanced electrocatalytic oxygen evolution reaction performance, with overpotentials of 200.4 and 240.4 mV at current densities of 10 and 100 mA cm⁻² in 1.0 M KOH, respectively, together with superior electrochemical stability.