Two-Dimensional NH<sub>4</sub>V<sub>3</sub>O<sub>8</sub> Nanoflakes as Efficient Energy Conversion and Storage Materials for the Hydrogen Evolution Reaction and Supercapacitors
Phuoc‐Anh Le, Van Qui Le, Thien Lan Tran, Nghia Trong Nguyen, Thi Viet Bac Phung, Van An Dinh
Abstract
High Resolution Image Download MS PowerPoint Slide Herein, for the first time, we present two-dimensional (2D) NH 4 V 3 O 8 nanoflakes as an excellent material for both energy conversion of the hydrogen evolution reaction and storage of supercapacitors by a simple and fast two-step synthesis, which exhibit a completely sheet-like morphology, high crystallinity, good specific surface area, and also stability, as determined by thermogravimetric analysis. The 2D-NH 4 V 3 O 8 flakes show an acceptable hydrogen evolution performance in 0.5 M H 2 SO 4 on a glassy carbon electrode (GCE) coated with 2D-NH 4 V 3 O 8, which results in a low overpotential of 314 mV at −10 mA cm –2 with an excellent Tafel slope as low as 90 mV dec –1 . So far, with the main focus on energy storage, 2D-NH 4 V 3 O 8 nanoflakes were found to be ideal for supercapacitor electrodes. The NH 4 V 3 O 8 working electrode in 1 M Na 2 SO 4 shows an excellent electrochemical capability of 274 F g –1 at 0.5 A g –1 for a maximum energy density of 38 W h kg –1 at a power density as high as 250 W kg –1 . Moreover, the crystal structure of 2D-NH 4 V 3 O 8 is demonstrated by density functional theory (DFT) computational simulation using three functionals, GGA, GGA + U, and HSE06. The simple preparation, low cost, and abundance of the NH 4 V 3 O 8 material provide a promising candidate for not only energy conversion but also energy-storage applications.