A1 Refereed original research article in a scientific journal
Harnessing true capacitive activity of nitrogen-doped MXene through hydrogel assembly and theoretical understanding of the role of dopant sites
Authors: Patra, Amalika; Dutta, Pronoy; Das, Mandira; Karim, Golam Masud; Deb, Sujit Kumar; Das, Snehasish; Mukherjee, Priyam; Ghosh, Subhradip; Maiti, Uday Narayan
Publisher: Elsevier Ltd
Publication year: 2024
Journal: Carbon
Journal name in source: Carbon
Article number: 119485
Volume: 229
eISSN: 1873-3891
DOI: https://doi.org/10.1016/j.carbon.2024.119485(external)
Web address : https://doi.org/10.1016/j.carbon.2024.119485(external)
Heteroatom nitrogen (N) doping in MXene can significantly push its energy storage metric. However, translating the intrinsic improvement of individual sheets into macroscopic electrodes is challenging due to the blockage of dopant sites by restacking. Here, we report the development of restack-controlled N-doped MXene hydrogel through speedy interfacial assembly methods to keep the dopant sites electrochemically accessible. Application of a small voltage between two zinc plates in an aqueous dispersion of N-doped MXene leads to the rapid development of doped hydrogel over the positive zinc plate via electrophoretic drag and linking by interfacial released zinc ions. As-developed hydrogels having continuous porosity and quasi-oriented sheet arrangement preserve ion transporting channels, thus allowing the surface dopant sites to participate in the supercapacitive energy storage actively. N-doped hydrogel displays a high capacitance of 488 F g−1 at 5 mV s−1 much higher as compared to compact film. The N-doped MXene hydrogels display excellent rate performance with retention over 88 % at 1000 mV s−1 and cyclic stability of 87 % over 10000 cycles. The detailed density functional theory (DFT) calculation reveals a major pseudocapacitive contribution from the surface adsorption and functional group substitution type N dopant sites as compared to another dopant site, namely, lattice substitution.
Funding information in the publication:
This work is supported by financial assistance from BRNS (grant no.: 58/14/27/2022/BRNS-37099 Dated November 11, 2022). We are thankful to the Central Instruments Facility (CIF), Indian Institute of Technology Guwahati (IITG) for their constant support and help in providing infrastructure and instrumental facilities. The authors greatly acknowledge IITG and C-DAC, India for providing the supercomputer PARAM-ISHAN high-performance computing (HPC) facility.
