Tailoring a Zinc Oxide Nanorod Surface by Adding an Earth‐Abundant Cocatalyst for Induced Sunlight Water Oxidation

• Published in: Chemphyschem Vol. 21; no. 6; pp. 476 - 483
• Main Authors: Almeida, Rafael M., Ferrari, Victoria C., S. Souza, Juliana, Souza, Flavio L., Alves, Wendel A.
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 17.03.2020
• Subjects: catalytic efficiency; Charge efficiency; Chemical reactions; Density; Deposition; Earth surface; Electrodes; Electromagnetic absorption; FeOOH nanoparticles; Glycine; Irradiation; Metal oxides; Nanoparticles; Nanorods; Oxidation; oxygen evolution reaction; Oxygen evolution reactions; Photoelectric effect; Photoelectric emission; Separation; solar water splitting; Sunlight; Zinc oxide; Zinc oxides; oxygen evolution reaction; solar water splitting; zinc oxide; FeOOH nanoparticles; catalytic efficiency
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201901171

Herein, a detailed investigation of the surface modification of a zinc oxide (ZnO) nanorod electrode with FeOOH nanoparticles dispersed in glycine was conducted to improve the water oxidation reaction assisted by sunlight. The results were systematically analysed in terms of the general parameters (light absorption, charge separation, and surface for catalysis) that govern the photocurrent density response of metal oxide as photoanode in a photoelectrochemical (PEC) cell. ZnO electrodes surface were modified with different concentration of FeOOH nanoparticles using the spin‐coating deposition method, and it was found that 6‐layer deposition of glycine‐FeOOH nanoparticles is the optimum condition. The glycine plays an important role decreasing the agglomeration of FeOOH nanoparticles over the ZnO electrode surface and increasing the overall performance. Comparing bare ZnO electrodes with the ones modified with glycine‐FeOOH nanoparticles an enhanced photocurrent density can be observed from 0.27 to 0.57 mA/cm2 at 1.23 VRHE under sunlight irradiation. The impedance spectroscopy data aid us to conclude that the higher photocurrent density is an effect associated with more efficient surface for chemical reaction instead of electronic improvement. Nevertheless, the charge separation efficiency remains low for this system. The present discovery shows that the combination of glycine‐FeOOH nanoparticle is suitable and environmentally‐friend cocatalyst to enhance the ZnO nanorod electrode activity for the oxygen evolution reaction assisted by sunlight irradiation. The use of FeOOH nanoparticles as a cocatalyst for nanostructured zinc oxide electrodes improves the oxygen evolution reaction in solar water splitting. The use of glycine as a dispersive agent for the nanoparticles leads to a homogeneous catalytic surface. The bulk and surface electronic contributions to the photoelectrochemistry are carefully studied.