Synthesis of Titanium Carbide MXene Nanosheets by Ecofriendly Technique for Strontium Ion Adsorption

2D titanium carbide (Ti3C2Tx, where Tx indicates the surface termination) MXene nanosheets are synthesized by etching the Ti3AlC2 MAX phase using two kinds of etchants: potassium hydroxide (KOH) base and hydrofluoric (HF) acid. This study aims to reduce the environmental side effects caused by the etchant in fabricating MXene nanosheets to extract strontium ions (Sr2+) from nuclear wastewater. Ti3C2Tx MXene synthesized using alkaline KOH etchant shows a 99% Sr2+ removal rate, which is much higher than that synthesized using the conventional HF etchant (82%). The enhanced Sr2+ removal rate associated with KOH etching is explained by unique surface termination, which offers more active adsorption sites for Sr2+ by the partial hydrolysis of TiC bonds on the surface of MXene nanosheets. Herein, a comparative analysis of the microstructure and properties of MXene nanosheets synthesized by KOH and HF etching is presented. The MXene nanosheets synthesized with KOH etchant show significantly higher Sr2+ adsorption capacity than those by HF. The underlying factors that enhance the Sr2+ adsorption associated with the KOH‐etched MXene nanosheets are also explained.