Evaluation of the electrocatalytic performance of Cu(Cr_0.1,Al_0.9)₂O₄ electrode by anodic oxidation of methylene blue

The degradation of industrial dyes poses a significant environmental challenge due to their persistence and toxicity. Developing efficient and stable electrode materials for the electrochemical degradation of methylene blue (MB) is crucial for addressing environmental concerns associated with dye pollution.

This paper describes the synthesis and electrochemical performance of Cu(Cr_0.1,Al_0.9)₂O₄ as a potential electrode material for the degradation of MB. The material was elaborated via nitrate synthesis and heat-treated at 900 °C. Then, characterized using various physico-chemical techniques. For all the electrochemicals tests, an anode based on Cu(Cr_0.1,Al_0.9)₂O₄ was prepared by adding activated carbon (AC), NMP and PVDF as binder agents.

Preliminary electrochemical tests indicated that the degradation of MB occurred via an indirect oxidation mechanism, which needs the integration of a supporting electrolyte. In this case, the electrolyte consists of mixture of Na₂SO₄ and NaCl at equal proportions (in volume). The pH study showed that the degradation efficiency was found vary between 92.4% and 97.2% at pH range 2–11. The electrode also exhibited excellent performance irrespective the dye concentrations, with efficiencies ranging from 91 to 99% for solutions at 6.4 to 40 ppm of MB.

The prepared electrode revealed a maximum degradation efficiency of 99% (within 50 min) at 50 mA applied current, for a 20 ppm MB solution. A higher current is required to decontaminate a concentrated solution. On the other hand, increasing the current reduces the electrolysis time. For a 40 ppm solution, the degradation efficiency reached 97.4% at an applied current of 70 mA within only 40 min.