(569cz) Robust Electrochemical Nitrate Reduction to Ammonia Using Activated Ti3C2Tx Mxene

Electrochemical nitrate reduction reaction (eNO₃RR) is a promising method to effectively produce ammonia (NH₃), which has recently attracted attention as a carbon-free fuel and hydrogen carrier. However, the eNO₃RR faces challenges both kinematically and thermodynamically due to competing hydrogen evolution reaction (HER). To suppress HER and enhance the eNO₃RR, an efficient electrocatalyst is required to promote the hydrogenation (*NH₂→*NH₃) known as rate determining step (RDS) of eNO₃RR. Ti₃C₂T_x MXene (T = O, OH, F, Cl) has attracted much attention as an electrocatalyst due to its large surface area and good electrical conductivity. Notably, Ti₃C₂T_x MXene with oxygen functional groups is known to promote hydrogenation process of eNO₃RR due to the weakening of *NH_x adsorption on the surface. In this study, Ti₃C₂T_x MXene was activated to have oxygen functional groups via simple electrochemical method, addressing limitations of conventional activation. As a result, the activated Ti₃C₂T_x MXene exhibited a 1.5-fold increase in NH₃ production rate (PR) and a 22% improvement in Faradaic efficiency (FE) compared to those of inactivated Ti₃C₂T_x MXene and achieved up to 2,942 μg∙h^-1∙cm^-2 NH₃ PR and 92.8% FE. This study experimentally proved that activated Ti₃C₂T_x MXene with oxygen functional groups is effective for eNO₃RR and is expected to provide insight into activation of MXene-based catalysts.