Orthorhombic (Co,Fe)Se2/Ti2C MXene porous microspheres for high-performance supercapacitors

In this work, the porous o-(Co,Fe)Se2/Ti2C MXene composite microspheres have been prepared using a facile and simple strategy via in-situ growth of orthorhombic o-(Co,Fe)Se2 on few-layered Ti2C MXene and subsequent vacuum calcination. The porous o-(Co,Fe)Se2/Ti2C composite microspheres exhibits a high reversible capacity of 286.2 mA h g–1 at a current density of 1 A g–1. In addition, the assembled asymmetric supercapacitor demonstrates a competitive energy density (68.9 Wh kg–1 at 800.0 W kg−1) and a robust long cycling stability (65.3 % capacitance retention after 10,000 cycles). The excellent electrochemical performance is described to the unique architecture of porous o-(Co,Fe)Se2/Ti2C microspheres and the synergistic effect of Fe doping and compositing with MXene. •Preparing porous o-(Co,Fe)Se2/Ti2C composite microspheres using a facile route.•Achieving an efficient synergy of doping and composite engineering in o-CoSe2.•Porous o-(Co,Fe)Se2/Ti2C shows a dramatically improved specific capacity.•Providing a feasible strategy for design of CoSe2 based energy-storage materials.