Hydrogen generation under visible light using nitrogen doped titania anodes

Lin, Hong; Rumaiz, Abdul K.; Schulz, Meghan; Huang, Chia-Hung; Shah, S. İsmat

doi:10.1063/1.3428514

Cited by 16 publications

(16 citation statements)

References 30 publications

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“…The maximum short current of 8.54 mA cm ‐2 and photoconversion efficiency ( η ) of 5.23% are obtained for the hierarchically porous N‐H‐TiO 2 films with a thickness of 5 μm (entry 7). This result is excellent in reported works because the hierarchically porous TiO 2 films have open frameworks as well as high crystallinity.…”

Section: Photoelectrocatalytic Water‐splitting Performance Of the Hiesupporting

confidence: 51%

“…The development of clean methods for generating energy is immensely important to preserve the global environment and ensure sustained economic growth. Photocatalytic water‐splitting can produce electric energy and hydrogen, which is also considered as an ideal clean fuel . Because both water and sunlight are vastly abundant, it has been considered one of the most altruistic forms of energy generation.…”

Section: Photoelectrocatalytic Water‐splitting Performance Of the Hiementioning

confidence: 99%

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Ordered Macro‐/Mesoporous Anatase Films with High Thermal Stability and Crystallinity for Photoelectrocatalytic Water‐Splitting

Zhang

Shen

et al. 2014

Advanced Energy Materials

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The development of clean methods for generating energy is immensely important to preserve the global environment and ensure sustained economic growth. Photocatalytic water-splitting can produce electric energy and hydrogen, which is also considered as an ideal clean fuel. [1][2][3][4][5][6][7][8][9] Because both water and sunlight are vastly abundant, it has been considered one of the most altruistic forms of energy generation. Among various semiconductors, titanium dioxide (TiO 2 ) has been recognized as one of the most suitable material for photocatalytic watersplitting due to its superior photovoltaic properties, low cost, high chemical inertness, and photostability. [10][11][12][13][14][15][16][17] Its wide band gap (3.2 eV for anatase phase) restrains the widespread uses because of the requirement of ultraviolet radiation for activation. Doping has been the most promising methods to extend the absorption in visible light, which can also bring other advantages, such as low recombination rate of electrons and holes and high anatase crystallinity. [18][19][20][21] Ordered mesoporous TiO 2 fi lms are among the best candidates as a host matrix for solar energy conversion because of their large surface areas, uniform pore sizes, structure homogeneity, and integrity. [22][23][24][25][26] However, there are two main limitations to the use of mesoporous TiO 2 fi lms in solar energy conversion. One is that the pore sizes of these fi lms are only several nanometers, which makes it diffi cult for effective mass transportation and diffusion through the pores and excludes large amounts of the internal surface. Although the mesopore sizes could be enlarged to 15-20 nm by using swelling agents or diblock copolymer (polystyreneblockpolyethylene oxide), [27][28][29][30] the improvement of accessibility is still limited because of the small windows of the mesopores. An attractive alternative is to build a hierarchically porous system by constructing macropores within the mesoporous fi lms, which can lead to more accessible pore openings and increase the availability of the internal surface. [31][32][33] The second limitation is the low crystallinity of mesoporous TiO 2 fi lms, as the mesostructure tends to collapse during the heat treatment at high temperatures (>450 °C) because of the intrinsic crystallization. Several methods have been developed to obtain highly crystalline mesoporous TiO 2 powder materials, including hardtemplating approach, combined assembly using soft and hard chemistry (CASH) methods, surfactant sulfuric acid carbonization method, etc. [34][35][36] Therefore, it is of signifi cant importance to fabricate hierarchically porous TiO 2 fi lms with high thermal stability and crystallinity. However, best to our knowledge, such highly stable and crystalline hierarchically porous TiO 2 fi lms have not yet been reported.Here, we demonstrate the synthesis of hierarchically ordered macro-/mesoporous TiO 2 fi lms (denoted as H-TiO 2 ) with high thermal stability and crystallinity using a confi ned evaporationinduced...

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Section: Photoelectrocatalytic Water‐splitting Performance Of the Hiesupporting

confidence: 51%

Section: Photoelectrocatalytic Water‐splitting Performance Of the Hiementioning

confidence: 99%

Ordered Macro‐/Mesoporous Anatase Films with High Thermal Stability and Crystallinity for Photoelectrocatalytic Water‐Splitting

Zhang

Shen

et al. 2014

Advanced Energy Materials

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“…In addition, the hydrazine treated titania films showed a higher degradation rate than undoped titania films illumination at both wavelengths. According to previous studies, nitrogen doping does not improve photocatalytic activity under UV light irradiation, and may actually deteriorate UV photoactivity [31,57,59]. The reason that UV photoactivity is not lost in the Ti 3+ -N-TiO2 films here is due to efficient reduction and nitrogen doping of the titania matrix of the amorphous sol-gel TiO2.…”

Section: Resultsmentioning

confidence: 67%

“…Common nonmetal dopants include C, F, N, S, P and B [8]. Among the nonmetal dopants, nitrogen is the most effective dopant due to its comparable atomic size to oxygen, low ionization potential, and high stability [7,9,17,[23][24][25][26][27][28][29][30][31][32][33][34][35].…”

Section: Introductionmentioning

confidence: 99%

Hydrazine-based synergistic Ti(III)/N doping of surfactant-templated TiO2 thin films for enhanced visible light photocatalysis

Islam

Rankin

2016

Materials Chemistry and Physics

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This study reports the preparation of titanium (Ti 3+) and nitrogen co-doped cubic ordered mesoporous TiO2 thin films using N2H4 treatment. The resulting co-doped TiO2 (Ti 3+-N-TiO2) thin films show significant enhancements in visible light absorption and photocatalytic activity. Cubic ordered mesoporous TiO2 thin films were prepared via a sol-gel method with Pluronic F127 as the pore template. After brief calcination, the TiO2 films were dipped into hydrazine hydrate which acts both as a nitrogen source and as a reducing agent, followed by heating at low temperature (90 °C). The hydrazine treatment period was varied from 5-20 hours to obtain different degrees of reduction and nitrogen doping. X-ray photoelectron spectroscopy (XPS) analyses and UV-vis absorbance spectra of Ti 3+-N-TiO2 films indicate that the incorporated N atoms and Ti 3+ reduce the band gap of TiO2 and thus enhance the absorption of visible light. The corresponding visible light photocatalytic activity of Ti 3+-N-TiO2 films was determined from the photocatalytic degradation of methylene blue under visible light illumination (at 455 nm). The Ti 3+-N-TiO2 films prepared with 10 hours of treatment show the optimum photocatalytic activity, with a pseudo-first order rate coefficient of 0.12 h-1 , which is 3 times greater than that of undoped TiO2 films. Calcination temperature and time were varied prior to hydrazine treatment to confirm that a brief calcination at low temperature (10 min at 350 °C) gave the best photochemical activity. In photoelectrochemical water oxidation using a 455 nm LED, the Ti 3+-N-TiO2 films prepared with 10 hours of N2H4 treatment show about 4 times the photocurrent compared to undoped TiO2 films. The present study suggests that hydrazine induced doping is a promising approach to enable synergistic incorporation of N and Ti 3+ into the lattice of surfactant-templated TiO2 films and enhanced visible light photoactivity, but that the benefits are limited by gradual mesostructure deterioration.

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“…For crystalline lattices, both interstitial and substitutional N doping of TiO 2 has been reported with the additional formation of detrimental oxygen vacancies [15]. However, the designation of interstitial or substitutional sites in amorphous thin films is not possible.…”

Section: Resultsmentioning

confidence: 99%

Incorporation of nitrogen into TiO₂thin films during PVD processes

Asenova

Manova

Mändl

2014

J. Phys.: Conf. Ser.

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Abstract. In this paper we investigate the possibility of incorporating nitrogen into amorphous, photocatalytic TiO 2 thin films, prepared at room temperature, during the growth process . The aim is to reduce the bandgap of the UV active thin films. Phys ical vapor deposition experiments employing a titanium vacuum arc with gas backfill ranging from pure oxygen to pure nitrogen, are carried out. The resulting films are characterized for chemical composition, phase composition, optical properties and hydrop hilicity in order to determine a correlation between gas composition and thin film properties. The experimental results point that a visible change in the band structure of the deposited layers is achieved .

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Hydrogen generation under visible light using nitrogen doped titania anodes

Cited by 16 publications

References 30 publications

Ordered Macro‐/Mesoporous Anatase Films with High Thermal Stability and Crystallinity for Photoelectrocatalytic Water‐Splitting

Ordered Macro‐/Mesoporous Anatase Films with High Thermal Stability and Crystallinity for Photoelectrocatalytic Water‐Splitting

Hydrazine-based synergistic Ti(III)/N doping of surfactant-templated TiO2 thin films for enhanced visible light photocatalysis

Incorporation of nitrogen into TiO₂thin films during PVD processes

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Hydrogen generation under visible light using nitrogen doped titania anodes

Cited by 16 publications

References 30 publications

Ordered Macro‐/Mesoporous Anatase Films with High Thermal Stability and Crystallinity for Photoelectrocatalytic Water‐Splitting

Ordered Macro‐/Mesoporous Anatase Films with High Thermal Stability and Crystallinity for Photoelectrocatalytic Water‐Splitting

Hydrazine-based synergistic Ti(III)/N doping of surfactant-templated TiO2 thin films for enhanced visible light photocatalysis

Incorporation of nitrogen into TiO2thin films during PVD processes

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Incorporation of nitrogen into TiO₂thin films during PVD processes