Modification of Surface States of Hematite-Based Photoanodes by Submonolayer of TiO2for Enhanced Solar Water Splitting

Lauri Palmolahti, Harri Ali-Löytty, Ramsha Khan, Jesse Saari, Nikolai V. Tkachenko, Mika Valden

Tutkimustuotos: ArtikkeliTieteellinenvertaisarvioitu

23 Sitaatiot (Scopus)
23 Lataukset (Pure)

Abstrakti

Surface states are inherently involved with photoelectrochemical (PEC) solar fuel production; some of them are beneficial and participate in the surface reactions, but some act as recombination centers and therefore limit the PEC efficiency. Surface treatments have been applied to modify the surface states, but interrelated effects of the treatments on both types of surface states have not been properly considered. This research examines the modification of the surface states on hematite-based photoanodes by atomic layer deposition of submonolayer amount of TiO2 and by postannealing treatments. Our results show that the postannealing causes diffusion of Ti deeper into the hematite surface layers, which leads to an increased saturation photocurrent and an anodic shift in the photocurrent onset potential. Without postannealing, the separate TiO2 phase on the hematite surface results in a second intermediate surface state and delayed charge carrier dynamics, i.e., passivation of the recombination surface states. It is evident by these results that the intermediate surface states observed with impedance spectroscopy in a PEC cell are directly involved in the surface reaction and not with the recombination surface states observed with ultrafast (picoseconds-nanoseconds) transient absorption spectroscopy in air. These results open new optimization strategies to control the beneficial and detrimental surface states independently.

AlkuperäiskieliEnglanti
Sivut13094-13101
Sivumäärä8
JulkaisuJournal of Physical Chemistry C
Vuosikerta124
Numero24
DOI - pysyväislinkit
TilaJulkaistu - 2020
OKM-julkaisutyyppiA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Rahoitus

This work was supported by the Academy of Finland (Decision Nos. 141481, 286713, 326406, 309920, and 326461), the Jane & Aatos Erkko Foundation (project “SOFUS”), and Business Finland (Decision No. 1464/31/2019). L.P. was supported by the KAUTE Foundation, H.A.-L. by the Jenny and Antti Wihuri Foundation, and J.S. by the Vilho, Yrjö and Kalle Väisälä Foundation of the Finnish Academy of Science and Letters. This work is part of the Academy of Finland Flagship Programme, Photonics Research and Innovation (PREIN) (Decision No. 320165).

Julkaisufoorumi-taso

  • Jufo-taso 2

!!ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Yleinen energiatiede
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

Sormenjälki

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