Hydrothermal Synthesis of Tetragonal MoB MBene: Process Optimization and Electrochemical Properties

Two‐dimensional (2D) transition metal borides, known as MBenes, possess remarkable properties such as high electrical conductivity, high thermal stability, and high Young's modulus, which make them excellent candidates for applications in energy storage, catalysis, and sensing. Despite such properties, research on MBenes is still at its nascent stage because they involve complex synthesis processes. Among various MBenes, 2D MoB MBene is being extensively investigated; however its synthesis remains time‐consuming, requires hazardous etchants, and results in residual salt contamination and undesirable secondary phases. Here, we demonstrate hydrothermal‐assisted etching of orthorhombic MoAlB phase using KOH solution at 170 °C for 14 h resulting in high‐purity tetragonal MoB MBene. The synthesized MoB exhibits a specific capacitance of approximately 127.5 F g ⁻¹ at 0.2 A g ⁻¹ in a 3‐electrode configuration. Further, the symmetric device containing MoB shows a high energy density of 29.4 μW h cm ⁻² at a power density of 2400 μW cm ⁻² . Our results provide an evidence of synthesis of high‐purity tetragonal MoB MBene, establish electrochemical properties‐phase relationship, and paves the way for its usage in various applications.