Zn(II)-MOFs nanosheets interaction with P-doped graphitic carbon nitride nanosheets for effective overall water splitting in alkaline medium

Abstract

We developed an electrocatalyst made up of two dimensional nanosheets interacted with another two-dimensional nanosheets (2D-2D) to explore the mediation of overall water splitting in alkaline medium. The 2D-2D electrocatalyst is denoted as ZIF-P-GCN nanosheets derived from metal organic frameworks (MOFs) such as zinc coordinated imidazole framework (ZIF-8) nanosheets interacted with optimized phosphorous doped graphitic carbon nitride (P-GCN) nanosheets. The developed electrocatalyst exhibits high efficiency for oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and overall water splitting. Initially, the electrocatalyst was studied using FT-IR spectra, XRD patterns, XPS analysis, BET surface area studies, FE-SEM and HR-TEM analyses to understand its structural and morphological properties. Moreover, the synthesized ZIF-P-GCN nanosheets are porous in nature, thereby subsequently, its electrocatalytic activity has been investigated. Compared to ZIF-8 or P-GCN nanosheets, the prepared 2D-2D interacted ZIF-P-GCN nanosheets loaded on the GCE electrode showed excellent and stable electrocatalytic performance with a low overpotential of 290 and 200 mV for OER and HER, respectively, to reach the current density of 10 mA cm−2 in alkaline medium. Besides, low Tafel slope values are observed such as 30.26 mV Dec-1 for OER and 46.53 mV Dec-1 for HER, respectively, in 3 M KOH. Furthermore, a complete electrochemical cell was constructed using ZIF-P-GCN//ZIF-P-GCN nanosheets loaded Ni foam electrodes for overall water splitting to achieve a minimum cell voltage of 1.61 V at a current density of 10 mA cm−2, which is comparable to standard Pt/C//RuO2 cell system. Thus, the work attempts to develop an effective and stable 2D-2D interacted bifunctional electrocatalyst for overall water splitting using a novel and easy route.