Synthesis of ZIF-9(III)/Co LDH layered composite from ZIF-9(I) based on controllable phase transition for enhanced electrocatalytic oxygen evolution reaction.

The ZIF-9(III)/Co LDH layered composite was successfully synthesized by a one-step controllable phase transition from ZIF-9(I). ZIF-9(III)/Co LDH nanosheets shows great OER electrocatalytic activity and exhibits a low overpotential of 297 mV at the current density of 10 mA cm−2 in 1.0 M KOH due to the high surface area, abundant metal sites and synergistic effect. [Display omitted] • A novel ZIF-9(III)/Co LDH was prepared by controllable phase transition of ZIF-9(I). • The fascinating structures and compositions of ZIF-9(III)/Co LDH are reported. • The optimized ZIF-9(III)/Co LDH exhibits efficient electrocatalytic performance. The quest for desirable two-dimensional (2D) materials and facile strategies to construct 2D layered composites with fascinating structures and compositions for high-performance electrocatalysis is still a major challenge. In the present research, novel nanocomposites of 2D zeolitic imidazolate framework-9 (ZIF-9) combined with Co-layered double hydroxide (Co LDH) were successfully synthetized through a controllable phase transition from ZIF-9(I). The 3D to 2D structural transformation of ZIF-9 was induced by deionized water, and the formation of 2D Co LDH was simultaneously realized during the one-step fabrication of ZIF-9(III)/Co LDH nanocomposites. Due to the high surface area, the presence of abundant metal sites, and the interactions between 2D ZIF-9(III) and 2D Co LDH, the as-optimized ZIF-9(III)/Co LDH nanocomposite exhibits great electrochemical activities for oxygen evolution reaction (OER) (η = 297 mV at 10 mA cm−2) in 1.0 M KOH solution. The electrochemical performance of the ZIF-9(III)/Co LDH nanocomposite was superior to those of the pure Co LDH, ZIF-9(III), and commercial RuO 2. The present work demonstrates that the proposed strategy can effectively boost catalytic activities and also design new routes to synthesize advanced MOF nanohybrids for various applications. [ABSTRACT FROM AUTHOR]