Article https://doi.org/10.1038/s41467-025-57999-w Isolated iridium oxide sites on modified carbon nitride for photoreforming of plastic derivatives Pawan Kumar 1,13 , Hongguang Zhang 1,13 , Asfaw G. Yohannes 2,13 , Jiu Wang 1 , Ali Shayesteh Zeraati 1,3 , Soumyabrata Roy 4,5 , Xiyang Wang 6 , Karthick Kannimuthu 1 , Abdelrahman M. Askar 7 , Kristen A. Miller 5 , Kexin Ling 8 , Muflih Adnan 1 , Sung-Fu Hung 9 , Jian-Jie Ma 9 , Wei-Hsiang Huang 10 , Dhwanil Trivedi 1 , Maria Molina 2 , Heng Zhao 1 , Angel A. Martí 5,8 , Adam F. G. Leontowich 11 , George K. H. Shimizu 2 , David Sinton 3 , Michael M. Adachi 7 , Yimin A. Wu 6 , Pulickel M. Ajayan 5 , Samira Siahrostami 12 , Jinguang Hu 1 & Md Golam Kibria 1 The rising concentration of plastics due to extensive disposal and inefficient recycling of plastic waste poses an imminent and critical threat to the envir- onment and ecological systems. Photocatalytic reforming of plastic deriva- tives to value-added chemicals under ambient conditions proceeds at lower oxidation potential which galvanizes the hydrogen evolution. We report the synthesis of a narrow band gap NCN-functionalized O-bridged carbon nitride (MC) through condensation polymerization of hydrogen-bonded melem (M)-cyameluric acid (C) macromolecular aggregate. The MC scaffold hosts well-dispersed Ir single atom (MCIrSA) sites which catalyze oxidative photo- reforming of alkali-treated polylactic acid (PLA) and polyethylene ter- ephthalate (PET) derivatives to produce H 2 at a rate of 147.5 and 29.58 μmol g -1 cat h -1 under AM1.5G irradiation. Solid-state electron paramagnetic reso- nance (EPR) and time-resolved photoluminescence (TRPL) reveals efficient charge carrier generation and separation in MCIrSA. X-ray absorption spec- troscopy (XAS) and Bader charge analysis reveal undercoordinated IrN 2 O 2 SA sites pinned in C 6 N 7 moieties leading to efficient hole quenching. The liquid phase EPR, in situ FTIR and density functional theory (DFT) studies validate the facile generation of •OH radicals due to the evolution of O-Ir-OH transient species with weak Ir--OH desorption energy barrier. Almost 80% of the ever-produced plastics (8.3 billion metric tons) are in the environment, mostly in water bodies and landfills due to improper disposal and recycling. Microplastics (plastic fragments <5 mm) are formed by weathering of synthetic plastics via physical, chemical, and biological processes. They are ubiquitous (24.4 trillion pieces) in the environment, especially in the aqueous medium, and are deleterious to the environment, human health, and biological ecosystem 1,2 . Hydrolysis of concentrated polymers followed by separation of monomers (i.e. terephthalic acid; TPA and EG for PET) is the current approach to recycle PET. However, the tedious separa- tion of monomers after neutralization and crystallization makes the process expensive 3 . Among various approaches, hydrothermal Received: 1 February 2024 Accepted: 7 March 2025 Check for updates A full list of affiliations appears at the end of the paper. e-mail: samira_siahrostami@sfu.ca; Jinguang.hu@ucalgary.ca; md.kibria@ucalgary.ca Nature Communications | (2025)16:2862 1 1234567890():,; 1234567890():,;