Constructing 2D/2D heterojunction of MnO2 nanolamellas grown on MXene nanosheets for boosted supercapacitor performance

Although supercapacitors are regarded as the next-generation power resources for various electronic devices, their broad-scale commercialization is largely dependent on the exploration and utilization of advanced electrode materials. Herein, we demonstrate an in situ oxidation approach to the construction of 2D/2D heterojunctions built from α-MnO2 nanolamellas grown on Ti3C2Tx MXene nanosheets through an ambient-temperature redox reaction. Interestingly, the growth density of MnO2 nanolamellas on MXene surface can be well controlled by regulating the reaction times, which endows the heterojunctions with adjustable composition, morphology, and microstructure. By virtue of the unique architectural merits including large accessible surface areas, uniform dispersion of MnO2 nanolamellas, well-contacted 2D/2D interfaces, and high electrical conductivity, the optimized MnO2/MXene heterojunction synthesized at a reaction time of 36 h exhibits boosted electrochemical performance with a high specific capacitance of 334.3 F g−1 at 0.5 A g−1, good rate property, and long cycle life with ~90.9 % capacitance retained after 5000 cycles, far outperforming those of bare MnO2 and MXene electrodes.