Self-Reduction Synthesis of New MXene/Ag Composites with Unexpected Electrocatalytic Activity

Differing from graphene, the activated groups on the surface of layered two-dimensional titanium carbide (MXene) materials bestow superiority to self-assemble some novel MXene derivatives with intriguing chemical/physical properties. Here we first report a series of new MXene-Ag composites by directly mixing AgNO3 and alkalization-intercalated MXene (alk-MXene, Ti3C2(OH/ONa)2) solution containing polyvinylpyrrolidone (PVP) at room temperature, in which an analogous urchin-shaped MXene-Ag0.9Ti0.1 bimetallic nanowire composite exhibits unexpected electrocatalytic activity for the oxygen reduction reaction. The addition of PVP solution induces the formation of 5-fold nanotwin Ag seeds, which then grow into Ag/Ti (Ag0.9Ti0.1) bimetallic nanowires. The unique bimetallic nanowires favor a four-electron transfer process, and exhibit high current density and good stability by offering numerous oxygen adsorption sites and shortening the diffusion path of adsorbed oxygen. The results represent a new step for the electrocatalytic applications of MXene materials, and also motivate enthusiasm in the quest for new MXene derivations.