Degradation of methylene blue under visible-light with copper-doped cobalt oxide nanoparticles

Abstract

Background

The development of efficient photocatalysts is greatly essential to degrade organic pollutants such as methylene blue (MB). Copper-doped cobalt oxide nanoparticles (Cu-Co₃O₄ NPs) have shown promise in enhancing photocatalytic activities due to their unique structural and optical properties.

Method

A hydrothermal approach was employed to synthesize Cu-Co₃O₄ NPs with varying Cu concentrations for the degradation of MB. XRD confirmed the cubic structure of Co₃O₄ NPs, with crystallite sizes decreasing from 29 nm (pure Co₃O₄) to 20 nm (15 % Cu-doped Co₃O₄). The FE-SEM/TEM micrographs revealed distinct shapes and morphologies. Additional peaks of the used Cu-Co₃O₄ NPs indicated interactions with MB. XANES and EXAFS analyses indicated electron transitions and structural modifications due to increased lattice strain with higher Cu concentrations.

Significance finding

This study reveals that Cu-Co₃O₄ NPs exhibited great performance compared to pure Co₃O₄ NPs. The Cu doping in Co₃O₄ nanoparticles enhanced their photocatalytic activity, achieving the highest degradation efficiency of 89 % for MB in 90 min under visible light with 15 % Cu doping. The results indicate the potential of Cu-Co₃O₄ NPs for the degradation of MB, offering valuable insights into the underlying mechanisms and practical applications of these catalysts. The optical band gap decreased from 3.1 eV for undoped Co₃O₄ to 2.1 eV for 15 % Cu-doped Co₃O₄ but increased after degradation, demonstrating their potential applications for environmental cleanup.