Enhanced oxygen evolution reaction on amine functionalized graphene oxide in alkaline medium

Development of highly efficient oxygen evolution reaction (OER) electrocatalysts is a critical challenge in the cost-effective generation of clean fuels. Here, a metal-free tyramine functionalized graphene oxide (T-GO) electrocatalyst is proposed to use in alkaline electrolytes for enhanced OER. Moreover, the T-GO and GO nanomaterials are well characterized by SEM, XRD, FTIR, XPS and Raman spectroscopy. T-GO exhibits an electrocatalytic OER with a current density of 2 mA cm−2 at a low onset potential of ∼1.39 V and a small Tafel slope of about 69 mV dec−1 and GO exhibits an onset potential of 1.51 V and Tafel slope of about 92 mV dec−1. Additionally, the current stability and RRDE based diffusion controlled response of the T-GO electrocatalyst are outstanding compared to GO. This study establishes metal free T-GO as an efficient electrocatalyst for the OER and used for cathodic production of hydrogen as a counter reaction in the field of water splitting.


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Figure S2.XPS survey spectra for C 1s of (a) GO and (b) T-GO respectively.

Figure S2 .
Figure S2.XPS survey spectra for O 1s of (a) GO and (b) T-GO respectively..

Figure S4 .
Figure S4.XPS survey spectra for N 1s of T-GO.

Figure S5 .
Figure S5.TGA superimposed for GO and T-GO.

Figure S6 .
Figure S6.Cyclic Voltammogram (CV) of GCE, GO and T-GO in 0.5 M KOH at scan 50 mV vs SCE.
Morphological study of graphene oxide (GO) as shown in Fig S1 the acitve sufrace sites of GO is less than tyramine-graphne (T-GO) the like wrinkeld folded structure of GO.The size of materials is depends om activity of materials in GO the less active sides becouses the morphology of GO is different from T-GO and electrochemcial activity also different.High Resolution XPS spectra of GO and T-GO XPS survey of GO and T-GO materials the XPS spectra of C 1s GO and T-GO are shown in Fig S2 A and B respectively in Fig S2 A the high resolution C 1s spectra of GO materials are show in three individual peaks at Electronic Supplementary Material (ESI) for RSC Advances.This journal is © The Royal Society of Chemistry 2019 284.8 eV, 286.1 eV and 289.1 eV corresponding to the C-C, C-O and COOH respectivley.In Fig S2 B high resolution C 1s signal was deconvoluted into four individual peaks ascribed to 284.5 eV, 286.1 eV and 288.2 eV corresponding to the C-C, C-O, C-N and C=O respectively.The O 1s excitation resolved into two peaks for both GO and T-GO are shown in Fig S3 A and B. The important peak after the tyramine functinalization of GO the exta XPS peak are observed for the N 1s signal was deconvoluted into two separate peask observed at 399.5 eV, 401 eV corresponding to the (NH-C=O), (C-N) respectively are show in Fig S4.
Cyclic voltammetric study of Bare GC, GO and T-GO nanomaterials are evalutaed in the alkaline media (0.5M KOH) with a standard three electrode system.Cyclic voltammograms were recorded from -0.2 to 1 V vs SCE and scan rate 50 mV s -1 the response of electrocatalyst shown in Fig S6 the T-GO in onset potential observed at ~0.23 V is very lower than the GCE and GO.The electrochemical performance of T-GO is indicated that the electrocatalyst performance of T-GO was excellent for the electrochemical OER applications as compare GO.The current density of electrocatalyst different (i) and different overpotential.The electron transfer reaction is faster in T-GO surface due to the additional funtinalities of sufrace of T-GO than GO.Lower the onset potential to indicate the better the electrocatalyst.

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Figure S2.XPS Spectroscopy of all the compound (A) XPS survey spectra of GO C1 s and (B) T-GO C 1s.

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Figure S3.XPS Spectroscopy of all the compound (A) XPS survey spectra of GO O1 s and (B) T-GO O 1s.

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Figure S5.TGA for GO and T-GO