Graphene Oxide Decorated with Rh Nanospheres for Electrocatalytic Water Splitting

Abstract

In this study, we report a method for fabrication of rhodium nanoparticles decorated on graphene oxide (Rh–GO) with high coverage of active sites of Rh nanospheres (NSs) on GO. It is one of the most pivotal aspects in the development of novel systems having high electrocatalytic performance toward overall water splitting reactions and is found to be better than universally acceptable Pt-based nanoelectrodes. The synthesis of nanohybrids shows the well-dispersed Rh NSs (∼50 nm) on a few layers of graphene oxide sheets. These as-synthesized nanomaterials were confirmed by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, Brunauer–Emmett–Teller (BET) surface area measurements, thermogravimetric analysis (TGA), and X-ray diffraction (XRD) analysis. Furthermore, Rh–GO exhibits significantly improved electrochemical performance toward electrocatalytic water splitting reactions, that is, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and it shows exceptionally an ultrasmall overpotential of 2 mV for the HER, reaching a current density of 10 mA cm–2 with a smaller Tafel slope 10 mV dec–1, and the OER overpotential reaches 0.23 V at 10 mA cm–2 with a Tafel slope of 27 mV dec–1. The reduced charge transfer resistances after Rh NSs decoration on GO which lead to simultaneous enhancement in feasibility toward interfacial electron transfer, result in an increase in activity toward overall water splitting reactions (both HER and OER).

Palladinized graphene oxide-MOF induced coupling of Volmer and Heyrovsky mechanisms, for the amplification of the electrocatalytic efficiency of hydrogen evolution reaction

“… 11 reported a functionalisation of GO with terminal nitrogen-containing groups (l-lysine) which resulted in efficient and stable electrocatalytic activity. The HER activities of rhodium nanoparticles decorated on graphene oxide (Rh–GO) were reported by Narwade et al 7 . They showed that Rh–GO composite possessed an improved electrochemical performance for water splitting reactions with a small overpotential of 2 mV for the HER at a current density of 10 mA cm −2 and Tafel slope of 10 mV dec –1 .…”

“…Currently, there is an increasing courtesy on the development of sustainable and clean energy sources 2 – 4 . Hydrogen from water splitting is recognised as a potential energy carrier 5 – 7 . This is due to advantages such as recyclability, free pollution, and high energy efficiency as compared to gasoline-based fuels 5 , 7 .…”

“…Hydrogen from water splitting is recognised as a potential energy carrier 5 – 7 . This is due to advantages such as recyclability, free pollution, and high energy efficiency as compared to gasoline-based fuels 5 , 7 . There are many ways for water splitting technology through hydrogen evolution reaction (HER), such as photoelectrochemical, photocatalytic, electrochemical, thermochemical, and photobiological methods 2 , 5 .…”

“…There are many ways for water splitting technology through hydrogen evolution reaction (HER), such as photoelectrochemical, photocatalytic, electrochemical, thermochemical, and photobiological methods 2 , 5 . Among many HER methods, eco-friendly and high purity of hydrogen can be obtained by an electrochemical technique which is considered as one of the most promising technologies for massive hydrogen production through hydrogen evolution reaction 7 . It was seen in the HER mechanism that Tafel analysis is used to get a better understanding of hydrogen production 5 , 6 .…”

“…It was seen in the HER mechanism that Tafel analysis is used to get a better understanding of hydrogen production 5 , 6 . It was demonstrated that in an acid medium, the HER pathway could proceed through three main mechanisms 7 , 8 . The first mechanism involves the adsorption of hydrogen ions on the surface of the electrode, leading to the formation of the composite hydride in the hydrogen storage process as the most probable intermediate and proposed to be the Volmer mechanism 5 – 8 .…”