Fluorine-doped titanium dioxide nanorod arrays for efficient photoelectrochemical water splitting

Abstract

TiO₂ is a well-known photocatalyst due to its excellent photocatalytic activity, low cost, and stability. However, its practical applications are limited by its poor charge transport and wide bandgap. In this study, F-doped TiO₂ nanorod arrays were synthesized using a simple chemical bath annealing method, which resulted in significantly improved properties. Among the samples, 0.05F-T (F-doped TiO₂ nanorods) exhibited the best performance, with a photocurrent of 7.34 mA/cm² at 1.8 V vs. reversible hydrogen electrode (RHE), which is 4.61 times higher than that of pure TiO₂ nanorods (1.59 mA/cm²). Incident photon-to-current efficiency measurements showed prominent photocurrent responses in the 325-375 nm range and a slight redshift toward the visible region around 425 nm, indicating improved light absorption. The electron-hole separation efficiency was enhanced, and bandgap and flat-band potential measurements confirmed the optimization of the energy band structure. The photoelectrochemical performance for water splitting was also evaluated, with 0.05F-T achieving the highest hydrogen production of 842.28 µmol/cm² in 5 h at 1.8 V vs. RHE, which is 6.58 times higher than that of pure TiO₂ (128.05 µmol/cm²). These results demonstrate that F-doped TiO₂ nanorods are promising for enhancing photocatalytic hydrogen production.

Highlights

1. A simple wet chemical soaking method introduces the Fluoride (F) element into the TiO₂ lattice.

2. F element doping changes the lattice spacing of TiO₂ and optimizes the band structure.

3. The doping of the F element causes a red shift in the wavelength of TiO₂ light absorption.

4. Efficient photoelectrochemical water splitting achieved by F-doped TiO₂ nanorods.

Keywords

Photoelectrochemical water splitting / TiO₂ nanorods / photoanodes / fluoride doping

References

[1] Scheffe JR,Patzke GR.Solar hydrogen production.Energy Tech2022;10:2101021

[2] Zou Z,Sayama K.Direct splitting of water under visible light irradiation with an oxide semiconductor photocatalyst.Nature2001;414:625-7

[3] Voloshchenko GN.Production of hydrogen through high-temperature electrolysis of water.Nanotechnol Russia2020;15:333-40

[4] Cai L,Xiang Y.Study on the reaction pathways of steam methane reforming for H₂ production.Energy2020;207:118296

[5] Fujishima A.Electrochemical photolysis of water at a semiconductor electrode.Nature1972;238:37-8

[6] Ding C,Wang Z.Photoelectrocatalytic water splitting: significance of cocatalysts, electrolyte, and interfaces.ACS Catal2017;7:675-88

[7] Cho IS,Lee CH,Prinz FB.Rapid and controllable flame reduction of TiO₂ nanowires for enhanced solar water-splitting.Nano Lett2014;14:24-31

[8] Tong M,Lin S.Ultra-thin carbon doped TiO₂ nanotube arrays for enhanced visible-light photoelectrochemical water splitting.Appl Surf Sci2023;623:156980

[9] Shi H,Ji M.A novel structure Ti/Fe₂O₃/Cu₂S/Co(OH)_x enhances the photoelectrochemical water splitting performance of iron oxide.Chem Synth2024;4:45

[10] Tan C,Wu XJ.Recent advances in ultrathin two-dimensional nanomaterials.Chem Rev2017;117:6225-331

[11] Qiu Y,Chen H.Current progress in developing metal oxide nanoarrays-based photoanodes for photoelectrochemical water splitting.Sci Bull (Beijing)2019;64:1348-80

[12] Lianos P.Review of recent trends in photoelectrocatalytic conversion of solar energy to electricity and hydrogen.Appl Catal B-Environ2017;210:235-54

[13] Kment S,Pausova S.Photoanodes based on TiO₂ and α-Fe₂O₃ for solar water splitting - superior role of 1D nanoarchitectures and of combined heterostructures.Chem Soc Rev2017;46:3716-69

[14] Jabbar ZH,Ammar SH.The latest progress in the design and application of semiconductor photocatalysis systems for degradation of environmental pollutants in wastewater: Mechanism insight and theoretical calculations.Mater Sci Semicond Process2024;173:108153

[15] Wang Y,Ho W,Zou Z.Biomolecule-controlled hydrothermal synthesis of C-N-S-tridoped TiO₂ nanocrystalline photocatalysts for NO removal under simulated solar light irradiation.J Hazard Mater2009;169:77-87

[16] Vorontsov AV.Structure, electronic and optical properties of bilayer anatase nanoribbons.Comput Mater Sci2018;155:266-81

[17] Meena B,Suryakala D,Subrahmanyam C.Efficient solar water splitting using a CdS quantum dot decorated TiO₂/Ag₂Se photoanode.Int J Hydrog Energy2021;46:34079-88

[18] Kaushal N,Tyagi S.NH₂-MIL-101(Fe)/N-CNDs as a visible light photocatalyst for degradation of fluoroquinolone antibiotics in water.Mater Chem Phys2025;332:130198

[19] Amal R,Wang Y.Enriched horizon of applied catalysis b: environment and energy.Appl Catal B- Environ2024;343:123593

[20] Han C,Zhao W.TiO₂/CeO₂ core/shell heterojunction nanoarrays for highly efficient photoelectrochemical water splitting.Int J Hydrog Energy2017;42:12276-83

[21] Guo Q,Ma Z.Fundamentals of TiO₂ photocatalysis: concepts, mechanisms, and challenges.Adv Mater2019;31:e1901997

[22] Abdelkarim O,Selopal GS.Constructing quantum dots sensitized TiO₂ nanotube p-n heterojunction for photoelectrochemical hydrogen generation.Chem Eng J2022;446:137312

[23] Sharma D.Nanostructured TiO₂ thin films sensitized by CeO₂ as an inexpensive photoanode for enhanced photoactivity of water oxidation.J Alloys Compd2018;749:329-35

[24] Yadav S.Review on undoped/doped TiO₂ nanomaterial; synthesis and photocatalytic and antimicrobial activity: review on undoped/doped TiO₂ nanomaterial.J Chin Chem Soc2017;64:103-16

[25] Huang J,Li J,Li M.Excellent visible light responsive photocatalytic behavior of N-doped TiO₂ toward decontamination of organic pollutants.J Hazard Mater2021;403:123857

[26] Dey S.Influence of Ce doping on morphology, crystallinity and photoelectrochemical charge transfer characteristics of TiO₂ nanorod arrays grown on conductive glass substrate.J Alloys Compd2021;881:160481

[27] Jiang X,YX .Bio-inspired materials for photocatalytic hydrogen production.Chin J Struct Chem2020;39:2123-30

[28] Jiang H,Liu J,Tian L.Alkali-free synthesis of a novel heterostructured CeO₂-TiO₂ nanocomposite with high performance to reduce Cr(VI) under visible light.Ceram Int2018;44:2709-17

[29] Lu H,Hu J.Fabrication of a TiO₂/Fe₂O₃ core/shell nanostructure by pulse laser deposition toward stable and visible light photoelectrochemical water splitting.ACS Omega2020;5:19861-7

[30] Long D,Bai L.Continuously selective photocatalytic CO₂ fixation via controllable S/Se ratio in a TiO₂-MoS_xSe_y dual-excitation heterostructured nanotree.ACS Photonics2020;7:3394-400

[31] Cho IS,Forman AJ.Branched TiO₂ nanorods for photoelectrochemical hydrogen production.Nano Lett2011;11:4978-84

[32] Cho IS,Feng Y.Codoping titanium dioxide nanowires with tungsten and carbon for enhanced photoelectrochemical performance.Nat Commun2013;4:1723

[33] Bayan E,Pustovaya L,Butova V.Zn-F co-doped TiO₂ nanomaterials: synthesis, structure and photocatalytic activity.J Alloys Compd2020;822:153662

[34] Cao X,Ma R.Ni₂P nanocrystals modification on Ta:α-Fe₂O₃ photoanode for efficient photoelectrochemical water splitting: In situ formation and synergistic catalysis of Ni₂P@NiOOH cocatalyst.Chem Eng J2022;449:137792

[35] Zhang K,Park C.Black phosphorene as a hole extraction layer boosting solar water splitting of oxygen evolution catalysts.Nat Commun2019;10:2001 PMCID:PMC6494903

[36] Dotan H,Grätzel M,Warren SC.Probing the photoelectrochemical properties of hematite (α-Fe₂O₃) electrodes using hydrogen peroxide as a hole scavenger.Energy Environ Sci2011;4:958-64

[37] Jia H,He Y.Engineering the defect distribution via boron doping in amorphous TiO₂ for robust photocatalytic NO removal.Appl Catal B-Environ Energy2024;356:124239

[38] Ma J,Chen G.Tuning the selectivity of photothermal CO₂ hydrogenation through photo-induced interaction between Ni nanoparticles and TiO₂.Appl Catal B- Environ2024;344:123600

[39] abstract: Angew Chem Int Ed. 40/2024.Angew Chem Int Ed2024;63:e202484011