TY - JOUR
T1 - Photoreforming of plastic waste into valuable products and hydrogen using a high-entropy oxynitride with distorted atomic-scale structure
AU - Hai, Ho Truong Nam
AU - Nguyen, Thanh Tam
AU - Nishibori, Maiko
AU - Ishihara, Tatsumi
AU - Edalati, Kaveh
N1 - Publisher Copyright:
© 2024 Elsevier B.V.
PY - 2025/5/15
Y1 - 2025/5/15
N2 - The persistent existence of plastic waste causes serious problems for the environment, directly and indirectly affecting the health of organisms and humans. Photoreforming is a nature-friendly method that only uses solar energy to convert plastic waste into green hydrogen (H2) and valuable organic products. This study shows that a high-entropy oxynitride (HEON) photocatalyst, synthesized by the addition of nitrogen to a Ti-Zr-Hf-Nb-Ta-containing high-entropy oxide (HEO), exhibits a higher potential for the production of H2, formic acid and acetic acid from polyethylene terephthalate (PET) photoreforming compared to the relevant HEO. Examination of X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) by synchrotron light shows that, in addition to hybridization of 2p orbitals from oxygen and nitrogen, nitrogen atoms distort the structure and completely change the neighborhood of niobium and titanium (a main contributor to the conduction band), expands the atomic bonds of zirconium and tantalum, contracts the atomic bonds of hafnium and decreases the binding energy of titanium, niobium and tantalum. These electronic structure changes lead to a narrower bandgap and diminished electron-hole recombination, enhancing the photoreforming performance. This study introduces HEONs with distorted atomic-bond structures as efficient low-bandgap and stable catalysts for transforming plastics into high-value organic chemicals and H2 by photocatalysis.
AB - The persistent existence of plastic waste causes serious problems for the environment, directly and indirectly affecting the health of organisms and humans. Photoreforming is a nature-friendly method that only uses solar energy to convert plastic waste into green hydrogen (H2) and valuable organic products. This study shows that a high-entropy oxynitride (HEON) photocatalyst, synthesized by the addition of nitrogen to a Ti-Zr-Hf-Nb-Ta-containing high-entropy oxide (HEO), exhibits a higher potential for the production of H2, formic acid and acetic acid from polyethylene terephthalate (PET) photoreforming compared to the relevant HEO. Examination of X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) by synchrotron light shows that, in addition to hybridization of 2p orbitals from oxygen and nitrogen, nitrogen atoms distort the structure and completely change the neighborhood of niobium and titanium (a main contributor to the conduction band), expands the atomic bonds of zirconium and tantalum, contracts the atomic bonds of hafnium and decreases the binding energy of titanium, niobium and tantalum. These electronic structure changes lead to a narrower bandgap and diminished electron-hole recombination, enhancing the photoreforming performance. This study introduces HEONs with distorted atomic-bond structures as efficient low-bandgap and stable catalysts for transforming plastics into high-value organic chemicals and H2 by photocatalysis.
KW - High-entropy alloys (HEAs)
KW - High-entropy ceramics
KW - High-pressure torsion (HPT)
KW - Hydrogen (H) production
KW - Microplastics
UR - http://www.scopus.com/inward/record.url?scp=85212954992&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85212954992&partnerID=8YFLogxK
U2 - 10.1016/j.apcatb.2024.124968
DO - 10.1016/j.apcatb.2024.124968
M3 - Article
AN - SCOPUS:85212954992
SN - 0926-3373
VL - 365
JO - Applied Catalysis B: Environmental
JF - Applied Catalysis B: Environmental
M1 - 124968
ER -