ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Comprehensive review of bimetallic heterogeneous catalysts for the removal of organic dyes via advanced oxidation processes

Harez Rashid Ahmed and Anu Mary Ealias

Department of Chemistry, College of Science, University of Sulaimani, Sulaymaniyah, Iraq

E-mail: harez.ahmed@univsul.edu.iq

Received: 2 March 2026  Accepted: 7 April 2026

Abstract:

The continuous release of synthetic organic dyes into aquatic environments remains a critical environmental challenge due to their structural complexity, toxicity, and resistance to conventional treatment methods. Advanced oxidation processes (AOPs), which generate highly reactive oxygen species, have emerged as effective technologies for degrading and mineralizing these persistent pollutants. In recent years, bimetallic metal oxide catalysts have attracted growing attention as advanced AOP catalysts owing to their synergistic redox behavior, enhanced electron-transfer efficiency, tunable electronic structures, and improved catalytic stability relative to monometallic oxides. This review critically examines the design principles, catalytic mechanisms, and performance trends of bimetallic metal oxide catalysts applied in dye degradation via AOPs. Particular emphasis is placed on widely investigated systems such as Fe–Co, Cu–Fe, Mn–Fe, and Co–Ni oxides, highlighting how intermetallic interactions, oxygen-vacancy formation, and multi-active-site architectures govern the generation of reactive oxygen species. The performance of these catalysts is systematically compared across major AOP pathways, including photocatalysis, Fenton-like reactions, persulfate activation, and electrochemical oxidation. Furthermore, mechanistic insights into radical and non-radical oxidation pathways, charge-carrier dynamics, and degradation pathways are discussed. Beyond performance evaluation, this review addresses key limitations that hinder practical application, including metal leaching, catalyst deactivation, energy consumption, and reduced efficiency in complex wastewater matrices. Finally, emerging strategies, including green synthesis approaches, catalyst support integration, and solar-driven hybrid AOP systems, are outlined as future directions to advance bimetallic metal oxide catalysts toward scalable and sustainable wastewater treatment technologies.

Graphical abstract

Schematic illustration of bimetallic heterogeneous catalysts activating oxidants (H₂O₂, PMS, and PDS) in advanced oxidation processes for the efficient degradation of organic dyes via radical and non-radical pathways

Keywords: Bimetallic metal oxides; Advanced oxidation processes (AOPs); Organic dye removal; Fenton-like catalysis; Environmental remediation

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04889-0

Chemical Papers 80 (9) 9891–9907 (2026)