Two-dimensional titanium carbide MXenes as efficient non-noble metal electrocatalysts for oxygen reduction reaction

MXenes, a new family of multifunctional two dimensional (2D) solid crystals integrating high electroconductivity and rich surface chemistries, are promising candidates for electrolysis, which, however, have rarely been reported. Herein, free-standing ultrathin 2D MXene nanosheets were successfully fabricated from bulky and rigid MAX phase ceramics by liquid exfoliation with HF etching (delamination) and TPAOH intercalation (disintegration). The high oxygen reduction reaction (ORR) performance has been obtained, due to the extremely small thickness of the asfabricated Ti3C2 around 0.5-2.0 nm, equivalent to the dimensions of single-layer or double-layer Ti3C2 nanosheets in thickness. The ORR performance of the obtained Ti3C2 MXene-based catalyst exhibits desirable activity and stability in alkaline media. This study demonstrates the potential of earth-abundant 2D MXenes for constructing high-performance and cost-effective electrocatalysts.