Promoted glucose electrooxidation at Ni(OH)2/graphene layers exfoliated facilely from carbon waste material

Abstract

Nowadays, the glucose electro-oxidation reaction (GOR) is considered one of the most important solutions for environmental pollution. The GOR is the anodic reaction in direct glucose fuel cells and hybrid water electrolysis. In this study, the GOR is boosted using a carbon support modified with Ni(OH)₂ as a non-precious catalyst. The carbon support, with in situ generated graphene nanosheets having a large surface area, grooves, and surface functional groups, is prepared via a simple electrochemical treatment of the carbon rods of an exhausted zinc-carbon battery. Ni(OH)₂ is electrodeposited on the surface of the functionalized exfoliated graphite rod (FEGR) via the dynamic hydrogen bubbling technique (DHBT) and tested for GOR. The thus-prepared Ni(OH)₂/FEGR electrode is characterized by SEM, mapping EDX, HR-TEM, XRD, and XPS characterization tools. Ni(OH)₂/FEGR displays an onset potential of 1.23 V vs. the reversible hydrogen electrode (RHE) and attains high current densities at lower potentials. Additionally, Ni(OH)₂/FEGR showed prolonged stability toward GOR by supporting a constant current over a long electrolysis time. The enhanced catalytic performance is attributed to the superb ionic and electronic conductivity of the catalyst. Importantly, ionic conductivity increased, due to (i) a large surface area of in situ generated graphene layers, (ii) enhanced distribution of active material during deposition using DHBT, and (iii) increased hydrophilicity of the underlying substrate. Therefore, the Ni(OH)₂/FEGR electrode can be used efficiently for GOR as a low-cost catalyst, achieving low onset potential and high current densities at low potentials.