Development of COF derived nanosheet composite for electrocatalysis

Abstract

In today's world, when fossil fuel reserves are depleting rapidly, and the amount of harm and contamination the use of fossil fuels causes to the environment, humans have to shift their attention to a more sustainable way of living. The most important aspect of making this shift involves generating and storing energy in a sustainable fashion. Some examples of generating this energy are through fuel cells and metal-air batteries. Moreover, energy can be stored sustainably in the form of chemical bonds such as H2 through electrochemical water splitting. However, electrochemical water splitting is limited by some drawbacks like the slow kinetics observed in the anodic oxygen evolution reaction (OER), and this can be improved by using suitable catalysts. The structure morphology of 2-dimensional covalent organic frameworks (COFs) is similar to that of graphenes, and their modular nature allows atomic level manipulations. The desirable properties of COFs, including their porous and crystalline nature, makes them excellent candidate catalyst supports. Here a nitrogen-rich porous 2D COF has been synthesised and used as a support for bimetallic (Ni, Co) nanosheets for the oxygen evolution reaction (OER). The composite synthesised here has recorded an overpotential of 347 mV @ 10 mA/cm2 (ƞ10). This activity can be credited to some extent to the ability of the COF to confine the size of the nanosheets without any capping agents to a regime that is usually difficult to access. This is possible due to the N-rich framework of the COF, which anchors the metal nanosheets. The long-range ordered framework of the COF provides a structure to disperse the nanosheets uniformly.