Z-scheme ZnO@PDA/CeO2 heterojunctions using polydopamine as electron transfer layer for enhanced photoelectrochemical H2 generation

ÇELEBİ N., ARLI F., SOYSAL F., SALİMİ K.

Materials Today Energy, vol.21, 2021 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 21
  • Publication Date: 2021
  • Doi Number: 10.1016/j.mtener.2021.100765
  • Journal Name: Materials Today Energy
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Compendex, INSPEC
  • Keywords: Z-scheme heterojunction, Electron transfer layer, PDA, Water splitting, ZnO/CeO2, H-2 generation
  • Ankara Yıldırım Beyazıt University Affiliated: Yes

Abstract

© 2021 Elsevier LtdIn this study, polydopamine (PDA)-bridged ZnO@PDA/CeO2 Z-scheme heterojunctions are rationally designed using PDA as an electron transfer mediator for an efficient photoelectrochemical water splitting under visible LED illumination. PDA-bridged construction not only provided the completely wrapping of ZnO nanoparticles (NPs) but also provided a biomimetic electron transfer layer with well-defined core-shell morphologies. Thanks to this novel Z-scheme heterostructure, an improved photocurrent density is recorded for ZnO@PDA/CeO2 photoanodes (251 μA/cm2 at 0.25 V vs. reversible hydrogen electrode [RHE]) under LED irradiation (30 mW/cm2), whereas a quite low photocurrent density (24 μA/cm2 at 0.25 V vs. RHE) is obtained in dark due to low separation of electron–hole pairs. Our results suggest that the presence of PDA provided a solid–solid interfacial interaction (between semiconductors: ZnO and CeO2) that facilitated the separation and pumping of photogenerated charge carries for enhanced photoelectrochemical water splitting. The Z-scheme charge transfer mechanism is verified using radical scavengers, radical trapping experiments, as well as X-ray photoelectron spectroscopy methods. This three-dimensional (3D) Z-scheme ternary heterostructures delivers a new insight in next generation of photocatalysts for efficient large-scale conversion of solar energy to H2 fuels as well as renewable energy revolution.