Customized Synthesis of 2D Ti₃C₂ MXene for Improved Overall Water Splitting

The pursuit of low-cost, facilely synthesized, and highly efficient noble metal-free electrocatalysts for water splitting has gained momentum. In this context, two-dimensional (2D) MXenes have emerged as promising electrocatalyst materials. In this study, we report an approach to improve the overall water splitting reactivity of the Ti3C2 MXene by modifying the synthesis of the Ti3AlC2 MAX phase. The MAX phase was synthesized through conventional heat treatment under an Ar atmosphere at 1400 degree celsius for 1 min, employing a carefully selected nonstoichiometric composition. The formation of secondary-phase TiC was found to be minimal when Ti/TiC/Al = 1/0.75/1.4 (termed 14TAC40) composition was heat-treated. The formation mechanism of Ti3AlC2 was elucidated using X-ray diffraction (XRD) and differential thermal analysis (DTA) techniques. The MXene (termed TC40) derived from the 14TAC40 MAX phase demonstrated improved performance in both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activities. The overpotential required for the HER and OER activity was 188 and 330 mV, respectively. This improvement in the performance of the TC40 MXene is attributed to its abundant active sites and high charge transfer capability. Furthermore, the TC40 MXene was also evaluated as a bifunctional electrocatalyst for comprehensive water splitting. The results reveal that 1.70 V potential was adequate for the TC40 MXene bifunctional electrocatalyst to achieve 10 mA/cm(2) current density. Importantly, the prepared catalyst exhibited durability throughout the overall water splitting reaction.