Reduced graphene oxide-intercalated graphene oxide nano-hybrid for enhanced photoelectrochemical water reduction

Belete Asefa Aragaw

doi:10.1007/s40097-019-00324-x

Abstract

This paper reports on the synthesis of reduced graphene oxide (RGO)-intercataled graphene oxide (GO) nano-hybrid and investigates its application in photoelectrochemical (PEC) water reduction. The optical, structural, and morphological properties of RGO-intercalated GO (RGO/GO) nano-hybrid were studied using UV–Visible spectroscopy, X-ray diffraction, and scanning electron microscopy, respectively. The reduction of GO to RGO was studied using FTIR spectroscopy. The XRD and FTIR investigation shows the strong π–π stacking interactions between the layered GO host–RGO guest sheets. An improvement in PEC water reduction activity was exhibited by RGO/GO nano-hybrid photoelectrode, with a maximum photocurrent of − 61.35 μA/cm2 for RGO 1 wt% in GO versus − 42.80 μA/cm2 for pristine GO photoelectrode (43% improvement). The mechanism for photocurrent enhancement was studied by electrochemical impedance analysis. The PEC performance enhancement of RGO/RO nano-hybrid photoelectrode is attributed to the strong π–π stacking interactions between RGO and GO, leading to superior electron collection and transportation by RGO and hence reduced charge carrier recombination. In addition, the UV–Visible absorption and Taut plot analysis showed the higher light harvesting efficiency of the RGO/GO compared to GO, displaying a band gap of 2.58 eV and 3.11 eV for RGO/GO and GO, respectively. The findings of this work show the potential of a strongly coupled layered host–guest nano-hybrids for high-performance optoelectronic materials.Graphic abstract

Highlights

The rise in demand for sustainable and carbon-free energy production drives the advancement of solar to electrical energy conversion and solar to chemical energy storage1 3 Vol.:(0123456789)Journal of Nanostructure in Chemistry (2020) 10:9–18 systems
The increasing reduced graphene oxide (RGO) loading amount from 0.5 to 5 wt% does not cause a significant change in the structure confirming that RGO sheets are acting as a nucleation center for growing a strongly coupled RGO/Graphene oxide (GO) nano-hybrid
The method is feasible to apply for other layered semiconductor host materials and conjugated molecules which could create strong π–π interaction with RGO

Summary

Introduction

Journal of Nanostructure in Chemistry (2020) 10:9–18 systems. Solar energy storage in hydrogen fuel generated through photoelectrochemical (PEC) water reduction, known since the first report by Fujishima and Honda [1], is a promising way to address energy and environmental issues. The best candidate materials for this purpose are one of the GO’s families, i.e., reduced graphene oxide (RGO) It is the reduced form of GO, where removing the oxygen containing functionalities and restoring the C=C double bond conjugation (aromaticity) give better electrical conducting property. Additional mode of interaction includes H-bonding due to the presence of O-containing functional groups This strong interaction between the RGO and GO sheets forms a strongly coupled RGO/ GO nanocomposite improving the electron transfer rate and lowering charge carrier recombination, thereby enhancing the PEC performance of RGO/GO nanocomposite relative to GO. The RGO/ GO nano-hybrid dispersion was drop-cast on FTO and dried overnight to make FTO/RGO/GO nano-hybrid photoelectrode the photoelectrode was characterized and PEC water reduction activity was investigated. An Autolab electrochemical work station with NOVA software was used for electrochemical measurement

Findings

Result and discussion

Conclusion