High density anchoring of NiMoS4 on ultrathin Ti3C2 MXene assisted by dopamine for supercapacitor electrode materials

Abstract MXenes have a broad application in electrochemical energy storage. However, the smooth surface of high-density MXenes makes it difficult to stabilize the anchored active material. In this study, ultrathin Ti3C2 MXenes were doped with a high density of NiMoS4 nanoparticles with the assistance of dopamine (DA). DA was adsorbed by the Ti3C2 surface (Ti3C2-DA) to form a negatively charged layer, which was beneficial for the enrichment of metal ions. NiMoS4 was anchored to Ti3C2-DA via a hydrothermal reaction. The resultant Ti3C2-DA-NiMoS4 heterostructure increased the exposure of NiMoS4 active sites, and reduced the decrease in specific capacitance caused by volume changes. Consequently, Ti3C2-DA-NiMoS4 exhibited excellent electrochemical performance with a high specific capacitance of 1288 F g−1 at 1 A g−1. In addition, an asymmetric supercapacitor based on a Ti3C2-DA-NiMoS4 positive electrode achieved a high energy density of 40.5 Wh kg−1 at 810 W kg−1, and demonstrated excellent cycling stability (capacitance retention of 89% after 9000 cycles at 10 A g−1). These results demonstrate that the Ti3C2-DA-NiMoS4 heterostructure is a prospective candidate material for high-performance supercapacitors.