A review on transition metal oxides based photocatalysts for degradation of synthetic organic pollutants

Athira Krishnan*, Anna Swarnalal, Divine Das, Midhina Krishnan, Viswanathan S. Saji, S. M.A. Shibli

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

12 Scopus citations


This review provides insight into the current research trend in transition metal oxides (TMOs)-based photocatalysis in removing the organic colouring matters from water. For easy understanding, the research progress has been presented in four generations according to the catalyst composition and mode of application, viz: single component TMOs (the first-generation), doped TMOs/binary TMOs/doped binary TMOs (the second-generation), inactive/active support-immobilized TMOs (the third-generation), and ternary/quaternary compositions (the fourth-generation). The first two generations represent suspended catalysts, the third generation is supported catalysts, and the fourth generation can be suspended or supported. The review provides an elaborated comparison between suspended and supported catalysts, their general/specific requirements, key factors controlling degradation, and the methodologies for performance evaluation. All the plausible fundamental and advanced dye degradation mechanisms involved in each generation of catalysts were demonstrated. The existing challenges in TMOs-based photocatalysis and how the researchers approach the hitch to resolve it effectively are discussed. Future research trends are also presented.

Original languageEnglish
Pages (from-to)389-417
Number of pages29
JournalJournal of Environmental Sciences
StatePublished - May 2024

Bibliographical note

Funding Information:
We acknowledge Department of Chemistry, Amrita School of Arts &Sciences, Amrita Vishwa Vidyapeetham, Amritapuri and Department of Chemistry, University of Kerala for supporting us by providing technical facilities (access to journals).

Publisher Copyright:
© 2023


  • Dye degradation
  • Photocatalysis
  • Supported catalysts
  • Suspended catalysts
  • Transition metal oxides and composites

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Environmental Science (all)


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