Electric-Field-Assisted Alkaline Hydrolysis of Metal–Organic Framework Bulk into Highly Porous Hydroxide for Energy Storage and Electrocatalysis

Abstract

Metal–organic frameworks (MOFs) have attracted tremendous attention in the field of supercapacitors and electrocatalysis due to their open metal sites and high surface area. However, their inherent instability and poor electrical conductivity lead to limited electrochemical performance. Herein, we have employed a new and simple strategy for converting MOF bulk into porous Zn–Co hydroxide composites with the assistance of electric fields with different cycles. This method can alter the migration behavior of charged molecules/ions and improve the nucleation rate of hydroxide, thus adjusting the morphology of derivatives. As a supercapacitor electrode, the optimal material of Zn0.3Co0.7(OH)2 with an electric-field application time of 1200 cycles shows excellent electrochemical performance with a high specific capacity of 981.2 C g–1 at 1 A g–1. Additionally, the fabricated asymmetric supercapacitor exhibits an energy density of 42.5 Wh kg–1 at a power density of 750.0 W kg–1 and a remarkable cycling stability (99% after 11,000 cycles). Simultaneously, the as-prepared Zn0.3Co0.7(OH)2 with an electric-field application time of 1200 cycles delivers prominent OER performances, which can exhibit low overpotentials of 300 and 326 mV at 50 and 100 mA cm–2, respectively, and shows a small Tafel slope of 31.5 mV dec–1. This study represents a new strategy for the synthesis of economical and efficient electrode materials for supercapacitors and OER electrocatalysts and offers a novel way for the mild preparation of nanoderivatives from MOFs.

Interface engineering of a hollow core-shell sulfur-doped Co2P@Ni2P heterojunction for efficient charge storage of hybrid supercapacitors

“…5(e-f)) [38]. Based on the plots (i = av b ) of peak current (i) and scanning speed (v), the values of b of all four materials are positive with the range of 0.5-1 [39,40]. The value of b of the S-Co2P@Ni2P is 0.68, indicating that the nanomaterials act via both the diffusion control and pseudocapacitance mechanisms such that the reversible intercalation and release of ions and Faradaic redox reactions ensure the high capacity of the S-Co2P@Ni2P hollow core-shell heterojunction (Fig.…”

Design and synthesis of mixed-ligand architectured Zn-based coordination polymers for energy storage

“…4b). 16,47,48 For the N 1s spectrum shown in Fig. 4c, the binding energies at 398.7, 399.7 and 400.5 eV correspond to the N-Zn, N-C and N-H bonds of Zn-CP, respectively.…”

“…The peaks at 531.4, 532.2 and 533.5 eV are assigned to Zn-O, Zn-OH 2 and C-O species, respectively. 47 The C 1s spectra of Zn-CP and Zn-CP/rGO are fitted to four peaks centred at 284.5, 285.7, 286.5 and 288.6 eV, which are related to C-C/CvC, C-N, C-O and O-CvO functional groups, respectively (Fig. S5 †).…”

By Introducing Multiple Hydrogen Bonds Endows MOF Electrodes with an Enhanced Structural Stability

“…However, there is no denying that the weak coordination bonds between metal ions and organic ligands give MOFs unstable structure, prone to collapse, further resulting in poor cycling stability − and thus limiting their practical applications. How to improve the cycling stability of MOF-based electrode materials is urgent.…”