Synergistic etching and intercalation enables ultrathin Ti_(3)C_(2)T_(x)and Nb_(2)CT_(x)MXene nanosheets

Transition metal-containing MXene has shown great potential in the promising research fields,and its performance strongly depends on the composition,structure,dimension,and surface chemistry.Thus,rational design and controllable synthesis of ultrathin two-dimensional(2D)MXene nanosheets with uniform surface terminations are of great importance.However,the use of 2D MXene,particularly in solar-powered photocatalysis and electrocatalysis,is restricted by the formation of thick,multi-layered MXene flakes with a small interlayer spacing produced from the conventional hydrofluoric acid(HF)etching method.In this work,we report a few-layer MXene nanosheets by solely employing a mixture of lithium fluoride and hydrochloric acid as the etching reagent.Synergic etching and intercalation technique endows MXene with ultrathin 2D nanostructures;moreover,the use of fluoride salt,rather than harmful HF,offers a safer and environmentally-friendly synthetic route for scalable green production of 2D MXene.Both the obtained Ti_(3)C_(2)T_(x)and Nb_(2)CT_(x)nanosheets show a highly efficient photoelectrochemical performance superior to highly stacked MXene flakes.This work highlights a mild,simultaneous etching and delamination strategy for the development of high quality of 2D MXene nanosheets.