CrB MBene: Synthesis, structural insights, and electrochemical performance assessment

In this study, CrB MBene, a member of two-dimensional transition metal borides, was successfully synthesized from the chromium aluminum boride (Cr 2 AlB 2 ) MAB phase using a 1.25 M HCl selective etching process. The effect of various etching times, including 12 h, 24 h, 36 h, and 48 h, on the structural and electrochemical properties of two-dimensional (2D) CrB MBenes was investigated. Time was a significant factor for the removal of interlayer Al from the Cr 2 AlB 2 MAB phase, resulting in the formation of CrB MBene nanostructures. The synthesized CrB MBenes exhibited a 2D plate-like morphology with enhanced electrochemical performance. Specifically, the CrB/36 electrode exhibited the best specific capacitance of 92.3 F/g at 0.1 A/g with 86.46 % pseudocapacitive contribution according to the Trasatti kinetic analysis. This discovery can pave the way for the synthesis of a wide range of novel 2D MBenes from MAB phases, potentially expanding the family of 2D materials with diverse compositions and properties. • A novel 2D CrB MBene was successfully synthesized via fluoride-free HCl etching from the Cr 2 AlB 2 MAB phase. • Structural and morphological analyses confirmed the formation of high-purity CrB nanosheets. • The CrB/36 electrode exhibited the highest specific capacitance of 92.3 F/g at 0.1 A/g.