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.