Phytochemical-Assisted Green Synthesis of Nickel Oxide Nanoparticles for Application as Electrocatalysts in Oxygen Evolution Reaction

Abstract

Electrocatalytic water splitting is a promising solution to resolve the global energy crisis. Tuning the morphology and particle size is a crucial aspect in designing a highly efficient nanomaterials-based electrocatalyst for water splitting. Herein, green synthesis of nickel oxide nanoparticles using phytochemicals from three different sources was employed to synthesize nickel oxide nanoparticles (NiOx NPs). Nickel (II) acetate tetrahydrate was reacted in presence of aloe vera leaves extract, papaya peel extract and dragon fruit peel extract, respectively, and the physicochemical properties of the biosynthesized NPs were compared to sodium hydroxide (NaOH)-mediated NiOx. Based on the average particle size calculation from Scherrer’s equation, using X-ray diffractograms and field-emission scanning electron microscope analysis revealed that all three biosynthesized NiOx NPs have smaller particle size than that synthesized using the base. Aloe-vera-mediated NiOx NPs exhibited the best electrocatalytic performance with an overpotential of 413 mV at 10 mA cm−2 and a Tafel slope of 95 mV dec−1. Electrochemical surface area (ECSA) measurement and electrochemical impedance spectroscopic analysis verified that the high surface area, efficient charge-transfer kinetics and higher conductivity of aloe-vera-mediated NiOx NPs contribute to its low overpotential values.

Highly active ruthenium sites stabilized by modulating electron-feeding for sustainable acidic oxygen-evolution electrocatalysis

“…S4 and Table S2, ESI †). [36][37][38] The field emission scanning electron microscopy (FESEM) image of the Mn 0.73 Ru 0.27 O 2Àd showed a typical nanoparticle morphology 2c), in accordance well with the XRD results. 39,40 The energy-dispersive X-ray spectroscopy (EDX) mapping images showed the homogenous distribution of Ru, Mn, and O elements, ensuring the formation of Mn 0.73 Ru 0.27 O 2Àd solid-solution oxides (Fig.…”

“…S4 and Table S2, ESI†). 36–38 The field emission scanning electron microscopy (FESEM) image of the Mn 0.73 Ru 0.27 O 2− δ showed a typical nanoparticle morphology (Fig. S5, ESI†), and an inner diameter of nearly 3 nm was observed from high-resolution transmission electron microscopy (HRTEM) images (Fig.…”

Green Nanotechnology: Recent Research on Bioresource-Based Nanoparticle Synthesis and Applications

“…NiO NPs were found to be photocatalysis for many pollutants [120][121][122][123]. ey were also found to be electrocatalysis for oxygen evolution reactions [124].…”

“…Two of the used green methods are peels, which are the peel extract of papaya and dragon fruit, in addition to the leaf extract of aloe vera. e resulting NPs were then employed as electrocatalysts in the oxygen evolution reaction with aloe vera extract-mediated NiO x NPs showing the highest electrocatalytic activity [124].…”

Heterogeneous Photocatalysis: A Solution for a Greener Earth

“…In the presented paper by Selvanathan et al [17], the green synthesis of nickel oxide nanoparticles using phytochemicals from three different sources was employed to synthesize nickel oxide nanoparticles (NiO x NPs) as an efficient nanomaterial-based electrocatalyst for water splitting. Nickel (II) acetate tetrahydrate was reacted in presence of aloe vera leaves extract, papaya peel extract, and dragon fruit peel extract, respectively, and the physicochemical properties of the biosynthesized NPs were compared with sodium hydroxide (NaOH)-mediated NiO x .…”