Department of Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China.
Phys Chem Chem Phys. 2018 Jun 27;20(25):17313-17323. doi: 10.1039/c8cp01247d.
The remarkable effect of divalent transition metal ions on the electrochemical performance of transition metal-based layered double hydroxides (LDHs) was systematically investigated via computational and experimental approaches. Ni3-xCoxAl-LDHs (x = 0, 1, 2, and 3) were synthesized on carbon paper by a unipolar pulse electrodeposition (UPED) method and used as electrodes in energy storage systems. The structures were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Their electrochemical performance was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The mechanism of different electrochemical performances with various divalent transition metal ions was investigated by the density functional theory (DFT) plus U method and molecular dynamics (MD) simulations. The computational and experimental data demonstrated that the electronic and ionic conductivity and deprotonation of NiAl-LDHs were improved by doping Co species, and the incorporation of Co and Ni cations enabled LDHs to exhibit a larger interlayer spacing which can facilitate the diffusion of OH- ions, indicating that NiCo2Al-LDHs had the highest specific capacitance.
通过计算和实验方法系统研究了二价过渡金属离子对基于过渡金属的层状双氢氧化物（LDHs）电化学性能的显著影响。采用单极脉冲电沉积（UPED）法在碳纸上合成了 Ni3-xCoxAl-LDHs（x = 0、1、2 和 3），并将其用作储能系统中的电极。通过 X 射线衍射（XRD）和 X 射线光电子能谱（XPS）对其结构进行了表征。通过循环伏安法（CV）和电化学阻抗谱（EIS）评估了它们的电化学性能。通过密度泛函理论（DFT）加 U 方法和分子动力学（MD）模拟研究了不同二价过渡金属离子具有不同电化学性能的机制。计算和实验数据表明，掺杂 Co 物种提高了 NiAl-LDHs 的电子和离子电导率以及去质子化，Co 和 Ni 阳离子的掺入使 LDHs 具有更大的层间距，从而有利于 OH-离子的扩散，表明 NiCo2Al-LDHs 具有最高的比电容。
