Architecting carbon-coated Mo 2 CT x /MoSe 2 heterostructures enables robust potassium storage.

Herein, carbon-coated MoSe 2 decorated Mo 2 CT x MXene heterostructures (MoSe 2 /Mo 2 CT x @C) have been fabricated. Mo 2 CT x works as a dual-function electron/ion conductor, which not only provides high conductivity and mechanical strength, but also prevents the severe self-aggregation of few layered MoSe 2 nanosheets. The high reversible capacities of 405 mA h g -1 at 100 mA g -1 after 150 cycles and 258 mA h g -1 at 2000 mA g -1 after 400 cycles could be achieved for a potassium-ion battery.