Room-Temperature Synthesis of NiCo-Layered Double Hydroxide/MXene Composites for High-Performance Supercapacitors

Abstract

The facile preparation of layered double hydroxides (LDHs)/MXene composite at room temperature is still challenging. Herein, we designed and developed a fast and roomtemperature synthesis method to fabricate NiCo-LDH/Ti 3 C 2 T x composites with sandwichlike layered structures via direct NaBH 4 reduction. DFT calculations show that such layered composites can reduce the hydrogen desorption energy and increase the electrical conductivity, which is advantageous to improving electrochemical performance of supercapacitors. These superior features result in the prominent electrochemical performance of the fabricated NiCo-LDH/5-Ti 3 C 2 T x composite electrode, including high specific capacitance (721.5 C/g at 1 A/g), outstanding rate capacity (about 85.2% from 1 to 10 A/g), and excellent stability (80.4% of capacitance retention after 5000 cycles at 5 A/g). This study provides a facile way to construct layered LDHs/ MXene composites with exceptional electrochemical performance, which is expected to be suitable for various applications.

Synergistic MXene/LDH heterostructures with extensive interfacing as emerging energy conversion and storage materials

“…143 Wang et al performed density functional theory (DFT) calculations to measure the interfacial energy and electron transport in a NiCo-LDH/Ti 3 C 2 T x composite. 122 An interlayer spacing of 1.77 Å and an interfacial adhesion energy of −5.1 eV indicated a strong interaction between the NiCo-LDH and Ti 3 C 2 T x . The mesoporous layered architecture of the hybrid provided numerous ion transfer channels, which boost the electron transfer of about 1.54 e per unit cell from the less conductive NiCo-LDH to the highly conductive Ti 3 C 2 T x , as shown in Fig.…”

“…The close interaction of the MXene and LDH was further conrmed by the presence of an intensive density of states (DOS) at the conduction band, which reduced the energy barrier for electron transfer and improved the conductivity of the MXene/LDH composite. 37,122,138 With stable interfacial interactions, the NiCo-LDH/Ti 3 C 2 T x heterostructure exhibited an outstanding rate capacity (85.2% from 1 to 10 A g −1 ) and capacitance retention (80.4% aer 5000 cycles). 122 Moreover, the supercapacitive performance of MXene/LDH also depends on the type of electrolyte used.…”

“…37,122,138 With stable interfacial interactions, the NiCo-LDH/Ti 3 C 2 T x heterostructure exhibited an outstanding rate capacity (85.2% from 1 to 10 A g −1 ) and capacitance retention (80.4% aer 5000 cycles). 122 Moreover, the supercapacitive performance of MXene/LDH also depends on the type of electrolyte used. Ti 3 C 2 T x /NiCo-LDH exhibited the best performance in the alkaline electrolyte as the available hydroxyl ions promoted the activity of NiCo-LDH and reacted with the -F terminations on Ti 3 C 2 T x MXene, improving the overall performance of the composite.…”

“…117 Wang et al reported the in situ vertical growth of NiCo-LDH nanosheets on Ti 3 C 2 T x . 122 The OH − groups on the MXene adsorbed Ni 2+ and Co 2+ ions, which were reduced by NaBH 4 solution, to form the hybrid. The vertically grown NiCo-LDH on both sides of the MXene formed a sandwich-like structure, preventing the aggregation of NiCo-LDH and the oxidation of the MXene.…”

“…It has been widely reported that the low amounts of MXene in the MXene/LDH hybrid lead to enhanced activity by preserving the active sites of the LDH from being masked by the lamellar structure of the MXene. 122 In addition, controlling the size and distribution of the in situ grown LDH on the MXene has been necessary to accelerate the ion diffusion at high current density. 34 Furthermore, the arrangement of the 2D sheets plays a crucial role in energy storage applications.…”