Atmosphere-dependent hydrogenation of TiO2 nanotubes synthesized via one- and two-step anodization for enhanced photoelectrochemical performance

Somayyeh Fateh; Mohammad Reza Khalili; Saeedeh Masumi; Elham Khorashadizade; Reza Tavangar; Sadegh Pour-Ali

doi:10.1016/j.apsusc.2026.166725

Atmosphere-dependent hydrogenation of TiO₂ nanotubes synthesized via one- and two-step anodization for enhanced photoelectrochemical performance

Somayyeh Fateh
, Mohammad Reza Khalili
, Saeedeh Masumi
, Elham Khorashadizade
, Reza Tavangar
, Sadegh Pour-Ali

Centre for Manufacturing and Materials

Sahand University of Technology
Université de Mons
Pasargad Institute for Advanced Innovative Solutions (PIAIS)
University of Alberta

Research output: Contribution to journal › Article › peer-review

2 Citations (Scopus)

2 Downloads (Pure)

Abstract

This study investigates the influence of hydrogenation atmosphere on the physicochemical and photoelectrochemical (PEC) properties of TiO₂ nanotube arrays fabricated via one-step (OSA) and two-step anodization (TSA). After anodization, samples were thermally hydrogenated at 500 °C under pure H₂, H₂/N₂ (10%/90%), and H₂/Ar (10%/90%) atmospheres. All samples retained the anatase phase with highly ordered nanotubular morphology. X-ray photoelectron spectroscopy revealed varying oxygen vacancy (O_Vs) concentrations, highest under pure H₂. UV–Vis and PL analyses confirmed band gap narrowing due to defect-induced mid-gap states. PEC measurements showed enhanced photocurrent densities of 477 µA/cm² (OSA-H) and 475 µA/cm² (TSA-H) at 1.23 V vs. RHE, with photoconversion efficiencies up to 3.01%. Electrochemical impedance spectroscopy and Mott–Schottky analysis indicated reduced charge transfer resistance and elevated donor density (N_d), with TSA-H reaching 3.51 × 10²² cm⁻³. Despite similar photocurrent outputs, TSA-H exhibited superior stability with only 4% decay, nearly 2.5 × lower than OSA-H. These findings demonstrate that while both the anodization strategy and the hydrogenation atmosphere affect performance, the latter plays a more dominant role in defect modulation and PEC enhancement, with pure H₂ treatment yielding the most conductive and stable TiO₂ photoanodes.

Original language	English
Article number	166725
Number of pages	12
Journal	Applied Surface Science
Volume	735
Early online date	26 Mar 2026
DOIs	https://doi.org/10.1016/j.apsusc.2026.166725
Publication status	Published - 30 Jul 2026

Bibliographical note

© 2026 The Author(s). Published by Elsevier B.V.
This is an Open Access article distributed under the terms of the Creative
Commons Attribution License (http://creativecommons.org/licenses/by/4.0/)
Under this licence, users are permitted to share, download, copy, and redistribute the material in any medium or format, and—where applicable—adapt or build upon the work, provided they comply with the conditions of the stated licence

Keywords

One- and two-step anodization
Oxygen vacancies (O)
Photoelectrochemical (PEC) H generation
Thermal hydrogenation
TiO nanotubes

ASJC Scopus subject areas

Condensed Matter Physics
Surfaces and Interfaces
Surfaces, Coatings and Films

Access to Document

10.1016/j.apsusc.2026.166725Licence: CC BY

Khalili2026VoRFinal published version, 13.1 MBLicence: CC BY

Cite this

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title = "Atmosphere-dependent hydrogenation of TiO2 nanotubes synthesized via one- and two-step anodization for enhanced photoelectrochemical performance",

abstract = "This study investigates the influence of hydrogenation atmosphere on the physicochemical and photoelectrochemical (PEC) properties of TiO2 nanotube arrays fabricated via one-step (OSA) and two-step anodization (TSA). After anodization, samples were thermally hydrogenated at 500 °C under pure H2, H2/N2 (10\%/90\%), and H2/Ar (10\%/90\%) atmospheres. All samples retained the anatase phase with highly ordered nanotubular morphology. X-ray photoelectron spectroscopy revealed varying oxygen vacancy (OVs) concentrations, highest under pure H2. UV–Vis and PL analyses confirmed band gap narrowing due to defect-induced mid-gap states. PEC measurements showed enhanced photocurrent densities of 477 µA/cm2 (OSA-H) and 475 µA/cm2 (TSA-H) at 1.23 V vs. RHE, with photoconversion efficiencies up to 3.01\%. Electrochemical impedance spectroscopy and Mott–Schottky analysis indicated reduced charge transfer resistance and elevated donor density (Nd), with TSA-H reaching 3.51 × 1022 cm−3. Despite similar photocurrent outputs, TSA-H exhibited superior stability with only 4\% decay, nearly 2.5 × lower than OSA-H. These findings demonstrate that while both the anodization strategy and the hydrogenation atmosphere affect performance, the latter plays a more dominant role in defect modulation and PEC enhancement, with pure H2 treatment yielding the most conductive and stable TiO2 photoanodes.",

keywords = "One- and two-step anodization, Oxygen vacancies (O), Photoelectrochemical (PEC) H generation, Thermal hydrogenation, TiO nanotubes",

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T1 - Atmosphere-dependent hydrogenation of TiO2 nanotubes synthesized via one- and two-step anodization for enhanced photoelectrochemical performance

AU - Fateh, Somayyeh

AU - Khalili, Mohammad Reza

AU - Masumi, Saeedeh

AU - Khorashadizade, Elham

AU - Tavangar, Reza

AU - Pour-Ali, Sadegh

N1 - © 2026 The Author(s). Published by Elsevier B.V. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) Under this licence, users are permitted to share, download, copy, and redistribute the material in any medium or format, and—where applicable—adapt or build upon the work, provided they comply with the conditions of the stated licence

PY - 2026/7/30

Y1 - 2026/7/30

N2 - This study investigates the influence of hydrogenation atmosphere on the physicochemical and photoelectrochemical (PEC) properties of TiO2 nanotube arrays fabricated via one-step (OSA) and two-step anodization (TSA). After anodization, samples were thermally hydrogenated at 500 °C under pure H2, H2/N2 (10%/90%), and H2/Ar (10%/90%) atmospheres. All samples retained the anatase phase with highly ordered nanotubular morphology. X-ray photoelectron spectroscopy revealed varying oxygen vacancy (OVs) concentrations, highest under pure H2. UV–Vis and PL analyses confirmed band gap narrowing due to defect-induced mid-gap states. PEC measurements showed enhanced photocurrent densities of 477 µA/cm2 (OSA-H) and 475 µA/cm2 (TSA-H) at 1.23 V vs. RHE, with photoconversion efficiencies up to 3.01%. Electrochemical impedance spectroscopy and Mott–Schottky analysis indicated reduced charge transfer resistance and elevated donor density (Nd), with TSA-H reaching 3.51 × 1022 cm−3. Despite similar photocurrent outputs, TSA-H exhibited superior stability with only 4% decay, nearly 2.5 × lower than OSA-H. These findings demonstrate that while both the anodization strategy and the hydrogenation atmosphere affect performance, the latter plays a more dominant role in defect modulation and PEC enhancement, with pure H2 treatment yielding the most conductive and stable TiO2 photoanodes.

AB - This study investigates the influence of hydrogenation atmosphere on the physicochemical and photoelectrochemical (PEC) properties of TiO2 nanotube arrays fabricated via one-step (OSA) and two-step anodization (TSA). After anodization, samples were thermally hydrogenated at 500 °C under pure H2, H2/N2 (10%/90%), and H2/Ar (10%/90%) atmospheres. All samples retained the anatase phase with highly ordered nanotubular morphology. X-ray photoelectron spectroscopy revealed varying oxygen vacancy (OVs) concentrations, highest under pure H2. UV–Vis and PL analyses confirmed band gap narrowing due to defect-induced mid-gap states. PEC measurements showed enhanced photocurrent densities of 477 µA/cm2 (OSA-H) and 475 µA/cm2 (TSA-H) at 1.23 V vs. RHE, with photoconversion efficiencies up to 3.01%. Electrochemical impedance spectroscopy and Mott–Schottky analysis indicated reduced charge transfer resistance and elevated donor density (Nd), with TSA-H reaching 3.51 × 1022 cm−3. Despite similar photocurrent outputs, TSA-H exhibited superior stability with only 4% decay, nearly 2.5 × lower than OSA-H. These findings demonstrate that while both the anodization strategy and the hydrogenation atmosphere affect performance, the latter plays a more dominant role in defect modulation and PEC enhancement, with pure H2 treatment yielding the most conductive and stable TiO2 photoanodes.

KW - One- and two-step anodization

KW - Oxygen vacancies (O)

KW - Photoelectrochemical (PEC) H generation

KW - Thermal hydrogenation

KW - TiO nanotubes

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DO - 10.1016/j.apsusc.2026.166725

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