Fabrication of Metal (Cu and Cr) Incorporated Nickel Oxide Films for Electrochemical Oxidation of Methanol

Rimsha Liaqat,Javed Iqbal,Muhammad Adil Mansoor,Sehar Shakir,S Wageh,Asim Jilani,Abul Kalam

doi:10.3390/cryst11111398

Abstract

Methanol electrochemical oxidation in a direct methanol fuel cell (DMFC) is considered to be an efficient pathway for generating renewable energy with low pollutant emissions. NiO−CuO and Ni0.95Cr0.05O2+δ thin films were synthesized using a simple dip-coating method and tested for the electro-oxidation of methanol. These synthesized electrocatalysts were characterized by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy. Different electrochemical techniques were used to investigate the catalytic activity of these prepared electrocatalysts for methanol oxidation, including linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA). In the presence of 0.3 M methanol, the current densities of NiO−CuO and Ni0.95Cr0.05O2+δ thin films were found to be 12.2 mA·cm−2 and 6.5 mA·cm−2, respectively. The enhanced catalytic activity of NiO−CuO and Ni0.95Cr0.05O2+δ thin films may be a result of the synergistic effect between different metal oxides. The Chronoamperometry (CA) results of the mixed metal oxide thin films confirmed their stability in basic media. Furthermore, the findings of electrochemical impedance spectroscopy (EIS) of mixed metal oxide thin films demonstrated a lower charge transfer resistance as compared to the pure NiO, CuO, and Cr2O3 thin films.

Highlights

Due to the rapid increase in worldwide energy consumption and detrimental environmental emissions from conventional fossil fuel, explorations of alternative clean energy resources and economical devices for efficient energy conversions are demanded [1,2,3,4]
It is believed that the replacement of Ni2+ ions and Cr3+ ions generated some distortions in the normal cubic structure of NiO that caused a slight shift in the X-ray diffraction spectroscopy (XRD) reflections
NiO−CuO and Ni0.95Cr0.05O2+δ thin films were fabricated on Fluorine-doped tin oxide (FTO) glass substrates via a facile dip-coating method followed by calcination at 500 ◦C

Summary

Introduction

Due to the rapid increase in worldwide energy consumption and detrimental environmental emissions from conventional fossil fuel, explorations of alternative clean energy resources and economical devices for efficient energy conversions are demanded [1,2,3,4]. Transition metal oxides and their composites have attracted considerable attention as electrocatalysts due to their low electrical resistance, low cost, easy preparation, and excellent catalytic activity [15,16,17,18] From among these metal oxide composites, nickel-based materials are emerging as one of the most promising candidates due to their chemical stability, electrical properties, and the ability to remove intermediate COad in alkaline media [19,20,21]. According to Ghanem et al, mesoporous NiO/N-CNF and Ni/Ni(OH) have shown excellent stability and electrochemical activity for the electro-oxidation of methanol in alkaline media These NiO based binary systems are expected to exhibit improved electrocatalytic efficacy in methanol oxidation [23]. Increasing the number of active sites improves NiO catalytic activity [24]

Methods

Results

Conclusion