Construction of rod-like cobalt-pyridinedicarboxylic acid/MXene nanosheets composites for hydrogen evolution reaction and supercapacitor

Metal-organic frameworks (MOFs) have attracted considerable attention in the field of energy storage and conversion due to their large specific surface area, regulatable pore structure and composition. However, the poor electrical conductivity and few active sites of MOFs impede their application. Herein, highly conductive MXene nanosheets are introduced to modulate the electronic conductivity and structure of rod-like Co-pyridinedicarboxylic acid (Co-PDC), and thus enhancing the electrochemical performance of MOFs. The heterostructural Co-PDC/MXene (CPM) was facily synthesized at room temperature. The as-prepared CPM-30 with 30 % MXene only requires the overpotential of 75.1 mV to achieve a current density of 10 mA cm-2 for hydrogen evolution reaction (HER), and the assembled electrolytic cell with CPM-30 and RuO2 as cathode and anode electrodes can achieve a current density of 10 mA cm-2 at a voltage of 1.65 V. In addition, CPM-10 exhibits a high specific capacitance of 583.1 F g-1 at 0.5 A g-1 and an excellent rate performance of 41.6 % at 50 A g-1. Furthermore, the assembled asymmetric supercapacitor CPM-10//AC exhibited an energy density of 15.55 Wh kg-1 at a power density of 750 W kg-1 and excellent stability with a capacitance retention rate of 95 % after 10,000 cycles. The excellent electrochemical properties of Co-PDC/MXene are attributed to the unique structure and synergistic effect of Co-PDC and MXene.