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A Heterostructure Photoelectrode Based on Two-Dimensional Covalent Organic Framework Film Decorated TiO₂ Nanotube Arrays for Enhanced Photoelectrochemical Hydrogen Generation.

ABSTRACT: The well-defined heterostructure of the photocathode is desirable for photoelectrochemically producing hydrogen from aqueous solutions. Herein, enhanced heterostructures were fabricated based on typical stable covalent organic framework (TpPa-1) films and TiO₂ nanotube arrays (NTAs) as a proof-of-concept model to tune the photoelectrochemical (PEC) hydrogen generation by tailoring the photoelectrode microstructure and interfacial charge transport. Ultrathin TpPa-1 films were uniformly grown on the surface of TiO₂ NTAs via a solvothermal condensation of building blocks by tuning the monomer concentration. The Pt₁@TpPa-1/TiO₂-NTAs photoelectrode with single-atom Pt₁ as a co-catalyst demonstrated improved visible-light response, enhanced photoconductance, lower onset potential, and decreased Tafel slope value for hydrogen evolution. The hydrogen evolution rate of the Pt₁@TpPa-1/TiO₂-NTAs photoelectrode was five times that of Pt₁@TpPa-1 under AM 1.5 simulated sunlight irradiation and the bias voltage of 0 V. A lower overpotential was recorded as 77 mV@10 mA cm^-2 and a higher photocurrent density as 1.63 mA cm^-2. The hydrogen evolution performance of Pt₁@TpPa-1/TiO₂-NTAs photoelectrodes may benefit from the well-matched band structures, effective charge separation, lower interfacial resistance, abundant interfacial microstructural sites, and surficial hydrophilicity. This work may raise a promising way to design an efficient PEC system for hydrogen evolution by tuning well-defined heterojunctions and interfacial microstructures.

SUBMITTER: Zhang Y

PROVIDER: S-EPMC9865276 | biostudies-literature | 2023 Jan

REPOSITORIES: biostudies-literature

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A Heterostructure Photoelectrode Based on Two-Dimensional Covalent Organic Framework Film Decorated TiO<sub>2</sub> Nanotube Arrays for Enhanced Photoelectrochemical Hydrogen Generation.

Zhang Yue Y Li Yujie Y Yu Jing J Sun Bing B Shang Hong H

Molecules (Basel, Switzerland) 20230113 2

The well-defined heterostructure of the photocathode is desirable for photoelectrochemically producing hydrogen from aqueous solutions. Herein, enhanced heterostructures were fabricated based on typical stable covalent organic framework (TpPa-1) films and TiO<sub>2</sub> nanotube arrays (NTAs) as a proof-of-concept model to tune the photoelectrochemical (PEC) hydrogen generation by tailoring the photoelectrode microstructure and interfacial charge transport. Ultrathin TpPa-1 films were uniformly ...[more]

PMID: 36677884

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Project description:Hydrogen production via water splitting has been extensively researched for its environmental friendliness, energy efficiency, and renewability. This study describes the development of TiO2-multiwalled carbon nanotube (MWCNT)-SiO2 composite thin-film electrodes via electrophoretic deposition (EPD) from a 2-propanol solution of MWCNTs including TiO2 and SiO2 gels. The TiO2 and SiO2 gels were prepared via the sol-gel method and by mixing in varying weight ratios to enhance the efficiency of photoelectrochemical water splitting. Dual sol-gel EPD incorporates MWCNTs with a C/TiO2 molar ratio of ≥0.25 while varying the TiO2/SiO2 molar ratio from 5 to 14; the electronic conductivity is improved owing to the pristine graphene structure of the MWCNTs along with hydrophilicity imparted by SiO2. In addition, the volume of SiO2 sol influences the anatase-to-rutile ratio, the TiO2 crystal size, and chemical bonds, thereby affecting the formation of new energy levels. The optimal volume of SiO2 sol results in elevated ultraviolet-visible absorbance, attributed to midgap states generated by a high anatase-to-rutile ratio and Ti-O-Si formation, further leading to a substantial effective carrier density for the photoelectrochemical water-splitting reaction. Furthermore, the valence band maximum (VBM) and conduction band minimum, estimated using ultraviolet photoelectron and ultraviolet-visible spectroscopies, exhibited a downward shift with increasing SiO2 sol volume, followed by an upward shift; meanwhile, the Fermi level in a Na2SO4 solution under stimulated solar light deepened. The highest photoelectrochemical performance is achieved at the optimal SiO2 sol volume, where the VBM is deep enough to minimize the water-splitting overpotential, and the flat-band potential aligns with the set potential, thereby reducing band bending with a negligible hole depletion layer at the TiO2-solution interface. The best TiO2-MWCNT-SiO2 composite exhibits a photocurrent ∼7.4 times higher than that of a TiO2-MWCNT electrode.

Dataset Information

A Heterostructure Photoelectrode Based on Two-Dimensional Covalent Organic Framework Film Decorated TiO₂ Nanotube Arrays for Enhanced Photoelectrochemical Hydrogen Generation.

Publications

A Heterostructure Photoelectrode Based on Two-Dimensional Covalent Organic Framework Film Decorated TiO<sub>2</sub> Nanotube Arrays for Enhanced Photoelectrochemical Hydrogen Generation.

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Dataset Information

A Heterostructure Photoelectrode Based on Two-Dimensional Covalent Organic Framework Film Decorated TiO2 Nanotube Arrays for Enhanced Photoelectrochemical Hydrogen Generation.

Publications

A Heterostructure Photoelectrode Based on Two-Dimensional Covalent Organic Framework Film Decorated TiO<sub>2</sub> Nanotube Arrays for Enhanced Photoelectrochemical Hydrogen Generation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

A Heterostructure Photoelectrode Based on Two-Dimensional Covalent Organic Framework Film Decorated TiO₂ Nanotube Arrays for Enhanced Photoelectrochemical Hydrogen Generation.