High-speed solid state fluorination of Nb2O5 yields NbO2F and Nb3O7F with photocatalytic activity for oxygen evolution from water

Lange, Martin; Khan, Ibrahim; Dören, René; Ashraf, Muhammad; Qurashi, Ahsanulhaq; Prädel, Leon; Panthöfer, Martin; Au, Marcus von der; Cossmer, Antje; Pfeifer, Jens; Meermann, Björn; Mondeshki, Mihail; Tahir, Muhammad Nawaz; Tremel, Wolfgang

doi:10.1039/d1dt00533b

Cited by 7 publications

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“…The conventional photocatalyt systems usually include organic dyes (QuPh + –NA, eosin Y, and fluorescein) bulk semiconductors (such as TiO 2 , g-C 3 N 4 , , SrTiO 3 , Ta 2 O 5 , other metal oxides, fluorides, , and sulfides) (Table ), and metal complexes (such as Ru, Ir, and Rh based complexes) as light absorbers. However, none of the above-mentioned systems are an ideal candidate for overall water splitting.…”

Section: Photocatalytic (Pc) and Photoelectrochemical (Pec) Water Spl...mentioning

confidence: 99%

“…PEC water splitting is an ideal approach to convert sunlight energy into chemical energy in the form of “green” H 2 fuel. , In this direction, the raw materials required (water and sunlight) are naturally abundant and economically viable. However, the biggest challenge associated with PEC water splitting is to synthesize or engineer a single photocatalytic system that can absorb in the visible portion of the solar spectrum and access the excited state, in which the electron (e – ) and hole (h + ) energies match there redox potentials (reduction of H + and oxidation of water). ,,, At the same time, it should be chemically stable under reaction conditions and able to efficiently separate the electron (e – ) and hole (h + ) pairs . Thermodynamically, splitting of water to H 2 and O 2 is an endothermic process having a positive value for the change in the Gibbs free energy (Δ G °) of around 237 kJ mol –1 .…”

Section: Photocatalytic (Pc) and Photoelectrochemical (Pec) Water Spl...mentioning

confidence: 99%

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Recent Trends in Sustainable Solar Energy Conversion Technologies: Mechanisms, Prospects, and Challenges

et al. 2023

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The current global transition from conventional fossil-fuel-based systems to green, sustainable, and renewable energy is realizing new challenges associated with device efficiencies. Among the green energy approaches available, efficient solar energy conversion into green chemical and electrical energy can ensure the upcoming demands of global future energy in an environmentally friendly and sustainable way. However, the sunlight energy cannot be utilized directly as a result of its intermittent and diffuse nature. This demands the development of efficient and economically viable technologies for its efficient conversion to an applicable source of energy. The practical realization of this dream on an industrial scale is still a longstanding challenge for researchers. Therefore, the scientists and technologists across the globe are in constant pursuit to develop/improve highly efficient, environmentally benign, and economically viable sustainable chemistry and engineering devices. At present, three technologies: (i) photoelectrochemical water splitting, (ii) photoreforming of plastic- or biomass-derived waste, and (iii) organic photovoltaics in the form of perovskite solar cells have emerged as the best for converting the sunlight energy into organic valuables and “green” H2 fuel or electricity. In this review, we will focus on introducing the basic principles, mechanistic insights, recent trends, and future prospects for solar to green energy using these technologies.

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Section: Photocatalytic (Pc) and Photoelectrochemical (Pec) Water Spl...mentioning

confidence: 99%

Section: Photocatalytic (Pc) and Photoelectrochemical (Pec) Water Spl...mentioning

confidence: 99%

Recent Trends in Sustainable Solar Energy Conversion Technologies: Mechanisms, Prospects, and Challenges

et al. 2023

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“…Photochemical processes have an almost unlimited and inexpensive energy base . Recent technologies for photochemical water splitting using sunlight irradiation come in two forms: (i) photoelectrochemical water splitting − and (ii) photoreforming. − In this review, we focus on the photoreforming approach due to its lower thermodynamic barrier, and pure H 2 production, which makes it more feasible without external bias, with additional advantages for the production of fine chemicals.…”

Section: Introductionmentioning

confidence: 99%

Photoreforming of Waste Polymers for Sustainable Hydrogen Fuel and Chemicals Feedstock: Waste to Energy

et al. 2023

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Energy from renewable resources is central to environmental sustainability. Among the renewables, sunlight-driven fuel synthesis is a sustainable and economical approach to produce vectors such as hydrogen through water splitting. The photocatalytic water splitting is limited by the water oxidation half-reaction, which is kinetically and energetically demanding and entails designer photocatalysts. Such challenges can be addressed by employing alternative oxidation half-reactions. Photoreforming can drive the breakdown of waste plastics and biomass into valuable organic products for the production of H 2 . We provide an overview of photoreforming and its underlying mechanisms that convert waste polymers into H 2 fuels and fine chemicals. This is of paramount importance from two complementary perspectives: (i) green energy harvesting and (ii) environmental sustainability by decomposing waste polymers into valuables. Competitive results for the generation of H 2 fuel without environmental hazards through photoreforming are being generated. The photoreforming process, mechanisms, and critical assessment of the field are scarce. We address such points by focusing on (i) the concept of photoreforming and up-to-date knowledge with key milestones achieved, (ii) uncovering the concepts and challenges in photoreforming, and (iii) the design of photocatalysts with underlying mechanisms and pathways through the use of different polymer wastes as substrates. CONTENTS

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“…Pentavalent (Nb,Ta)-based inorganic oxyfluorides represent a rich family of compounds, synthesized and structurally characterized from the 1950s to the 2000s, including NbO 2 F, − TaO 2 F, , Nb 3 O 7 F, ,, Ta 3 O 7 F, , Nb 5 O 12 F, Nb 17 O 42 F and Nb 31 O 77 F, , Nb 3 O 5 F 5 , and NbOF 3 and TaOF 3 . They exhibit interesting physical properties such as photocatalytic activity (MO 2 F (M = Nb, , Ta , ) and M 3 O 7 F (M = Ta, Nb ,, )), electrochromism (NbO 2 F), almost-zero thermal expansion (TaO 2 F), − and Li + intercalation (NbO 2 F, ,, Nb 3 O 7 F , ). Except in Nb 17 O 42 F and MOF 3 (M = Nb, Ta) crystal structures, O 2– and F – are randomly distributed on all anion sites. ,,,− ,, In Nb 17 O 42 F, O 2– and F – are randomly distributed on only two of the anion sites, and in MOF 3 , O 2– and F – are preferentially distributed.…”

Section: Introductionmentioning

confidence: 99%

Structural Modeling of O/F Correlated Disorder in TaOF₃ and NbOF_3–x(OH)_x by Coupling Solid-State NMR and DFT Calculations

Zakary,

Body,

Charpentier

et al. 2023

Inorg. Chem.

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The structure of MOF 3 (M = Nb, Ta) compounds was precisely modeled by combining powder X-ray diffraction, solid-state NMR spectroscopy, and semiempirical dispersion-corrected DFT calculations. It consists of stacked ∞ (MOF 3 ) layers along the c⃗ direction formed by heteroleptic cornerconnected MX 6 (X = O, F) octahedra. 19 F NMR resonance assignments and occupancy rates of the anionic crystallographic sites have been revised. The bridging site is shared equally by the anions, and the terminal site is occupied by F only. An O/F correlated disorder is expected since cis-MO 2 F 4 octahedra are favored, resulting in one-dimensional −F−M−O−M− strings along the <100> and <010> directions. Ten different 2 × 2 × 1 supercells per compound, fulfilling these characteristics, were built. Using DFT calculations and the GIPAW approach, the supercells were relaxed and the 19 F isotropic chemical shift values were determined. The agreement between the experimental and calculated 19 F spectra is excellent for TaOF 3 . The 1 H and 19 F experimental NMR spectra revealed that some of the bridging F atoms are substituted by OH groups, especially in NbOF 3 . New supercells involving OH groups were generated. Remarkably, the best agreement is obtained for the supercells with the composition closest to that estimated from the 19 F NMR spectra, i.e., NbOF 2.85 (OH) 0.15 .

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High-speed solid state fluorination of Nb₂O₅ yields NbO₂F and Nb₃O₇F with photocatalytic activity for oxygen evolution from water

Abstract: Solid state reactions are slow, because the diffusion of atoms or ions through reactant, interme-diate and crystalline product phases is the rate-limiting step. This requires days or even weeks of...

Cited by 7 publications

References 54 publications

Recent Trends in Sustainable Solar Energy Conversion Technologies: Mechanisms, Prospects, and Challenges

Recent Trends in Sustainable Solar Energy Conversion Technologies: Mechanisms, Prospects, and Challenges

Photoreforming of Waste Polymers for Sustainable Hydrogen Fuel and Chemicals Feedstock: Waste to Energy

Structural Modeling of O/F Correlated Disorder in TaOF₃ and NbOF_3–x(OH)_x by Coupling Solid-State NMR and DFT Calculations

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High-speed solid state fluorination of Nb2O5 yields NbO2F and Nb3O7F with photocatalytic activity for oxygen evolution from water

Abstract: Solid state reactions are slow, because the diffusion of atoms or ions through reactant, interme-diate and crystalline product phases is the rate-limiting step. This requires days or even weeks of...

Cited by 7 publications

References 54 publications

Recent Trends in Sustainable Solar Energy Conversion Technologies: Mechanisms, Prospects, and Challenges

Recent Trends in Sustainable Solar Energy Conversion Technologies: Mechanisms, Prospects, and Challenges

Photoreforming of Waste Polymers for Sustainable Hydrogen Fuel and Chemicals Feedstock: Waste to Energy

Structural Modeling of O/F Correlated Disorder in TaOF3 and NbOF3–x(OH)x by Coupling Solid-State NMR and DFT Calculations

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High-speed solid state fluorination of Nb₂O₅ yields NbO₂F and Nb₃O₇F with photocatalytic activity for oxygen evolution from water

Structural Modeling of O/F Correlated Disorder in TaOF₃ and NbOF_3–x(OH)_x by Coupling Solid-State NMR and DFT Calculations