Affiliation:
1. School of Chemistry and Chemical Engineering Northwestern Polytechnical University No. 1 Dongxiang Road, Chang'an Xi'an Shaanxi 710129 P. R. China
2. Innovation Center NPU Chongqing Northwestern Polytechnical University Chongqing 400000 P. R. China
3. College of Materials Science and Engineering Xi'an University of Science and Technology Xi'an Shaanxi 710054 P. R. China
4. State Key Laboratory of Electrical Insulation and Power Equipment, Center of Nanomaterials for Renewable Energy, School of Electrical Engineering Xi’an Jiaotong University Xi’an 710049 P. R. China
Abstract
AbstractNitrogen‐doped titanium carbides (MXene) films exhibit extraordinary volumetric capacitance when high‐concentration sulfuric acid electrolyte is utilized owing to the enhancement of pseudocapacitance. However, the energy storage mechanism of nitrogen‐doped MXene is unclear due to the complex electrode structure and electrolyte ions’ behavior. Here, based on pristine MXene (Ti3C2O2), three different MXene structures are constructed by introducing metal vacancy sites and doped nitrogen atoms, namely, defective MXene (Ti2.9C2O2), nitrogen‐doped MXene (Ti3C2O1.9N0.1), and nitrogen‐doped MXene with metal vacancy sites (Ti2.9C2O1.9N0.1). Then, the density functional theory (DFT)‐based calculations coupled with the effective screening medium reference interaction site method (ESM‐RISM) are applied to reveal the electrochemical behavior at the electrode/electrolyte interfacial area. Through analyzing the electronic structure, electrical double‐layer capacitance (EDLC), and equilibrium potential of the pseudocapacitance reaction, the specific effect of structural changes on their performance can be clarified: metal vacancy sites can reduce the potential difference of gap layer (Outer Helmholtz plane) at charged state and increase the electronic capacity of Ti, which can be used to explain the high pseudocapacitance, low charge transfer resistance and high‐rate capacity properties of nitrogen‐doped MXene observed in experiments.
Funder
National Natural Science Foundation of China
Key Research and Development Projects of Shaanxi Province
Natural Science Foundation of Chongqing Municipality
Subject
Biomaterials,Biotechnology,General Materials Science,General Chemistry