2D-Ti3C2Tx MXene-supported Cu2S nanoflakes for supercapacitors and electrocatalytic oxygen evolution reaction

Recently, the design of efficient multifunctional materials for supercapacitors and oxygen evolution reaction (OER) has become imperative in the field of energy storage and conversion. In the present study, novel Cu2S-MXene heterostructures were synthesized, which exhibited multifunctional electrochemical properties. First, the charge storage properties of these heterostructures were investigated, and among the synthesized materials, 50Cu2S-50MXene exhibited superior properties with a specific capacity of 1874.1C g−1 in a 3 M KOH + 0.1 M K4[Fe(CN)6] electrolyte system. Subsequently, a flexible all-solid-state supercapacitor device was constructed using 50Cu2S-50MXene as the cathode and porous carbon derived from spent tea-waste as the anode separated by the electrolyte encapsulated with PVA gel. This device exhibited an excellent energy density of 79.7 W h kg−1 at a power density of 1730.3 W kg−1, which exceeds the performance of previously reported MXene-based ASC devices. Also, the device exhibited extreme flexibility and long cycle life (∼5000 cycles) and its practical utilization was demonstrated by illuminating a panel of LED lights. Furthermore, the multifunctionality of the materials was tested by performing electrocatalytic oxygen evolution reaction (OER). Among them, 50Cu2S-50MXene showed the highest catalytic activity, which exhibited an overpotential of 250 mV (at 25 mA cm−2), Tafel slope of 61 mV dec−1, exchange current density of 145.56 mA cm−2 and the maximum TOF of 4.52 s−1. The catalyst showed no significant deviation in its performance even after 2000 LSV scans with cycling stability for a maximum of 20 h. Hence, this study offers new insight for the exploration of novel multifunctional Cu2S-MXene hybrid heterostructures in both energy storage and conversion.