Activated TiO2 with tuned vacancy for efficient electrochemical nitrogen reduction

Han, Zishan; Choi, Changhyeok; Hong, Song; Wu, Tai‐Sing; Soo, Y. L.; Jung, Yousung; Qiu, Jieshan; Sun, Zhenyu

doi:10.1016/j.apcatb.2019.117896

Cited by 231 publications

(155 citation statements)

References 45 publications

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“…Thus, the diamond can be capable of initiating higher energy reduction reactions. Previous studies reported the approach for reduction of nitrogen was firstly and subsequently studied by using modified forms of TiO 2 [ 60 , 61 ]. The N 2 fixation yield in the visible area was less than 67%, due to the re-oxidation of intermediates and products by the pores in the deep valence band of TiO 2 and weak absorption on the surface of reactant.…”

Section: Discussionmentioning

confidence: 99%

“…The N 2 fixation yield in the visible area was less than 67%, due to the re-oxidation of intermediates and products by the pores in the deep valence band of TiO 2 and weak absorption on the surface of reactant. In addition, the work function of TiO 2 is 4.6 eV, which means electrons jumped to above the conduction band with barrier [ 60 , 61 , 62 , 63 ]. Other wide bandgap semiconductors such as GaN, SiC, due to lower potential energy, have more difficulty for the photocatalyst [ 56 , 64 , 65 ].…”

Section: Discussionmentioning

confidence: 99%

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Visible-Light Activation of Photocatalytic for Reduction of Nitrogen to Ammonia by Introducing Impurity Defect Levels into Nanocrystalline Diamond

Liu

Abbasi

et al. 2020

Materials

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Nitrogen impurity has been introduced in diamond film to produce a nitrogen vacancy center (NV center) toward the solvated electron-initiated reduction of N2 to NH3 in liquids, giving rise to extend the wavelength region beyond the diamond’s band. Scanning electron microscopy and X-ray diffraction demonstrate the formation of the nanocrystalline nitrogen-doped diamond with an average diameter of ten nanometers. Raman spectroscopy and PhotoLuminescence (PL) spectrum show characteristics of the NV0 and NV− charge states. Measurements of photocatalytic activity using supraband (λ < 225 nm) gap and sub-band gap (λ > 225 nm) excitation show the nitrogen-doped diamond significantly enhanced the ability to reduce N2 to NH3 compared to the polycrystalline diamond and single crystal diamond (SCD). Our results suggest an important process of internal photoemission, in which electrons are excited from negative charge states into conduction band edges, presenting remarkable photoinitiated electrons under ultraviolet and visible light. Other factors, including transitions between defect levels and processes of reaction, are also discussed. This approach can be especially advantageous to such as N2 and CO2 that bind only weakly to most surfaces and high energy conditions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Visible-Light Activation of Photocatalytic for Reduction of Nitrogen to Ammonia by Introducing Impurity Defect Levels into Nanocrystalline Diamond

Liu

Abbasi

et al. 2020

Materials

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“…Among the various types of defects, oxygen vacancies, which can be created easily by thermal treatment under a reductive atmosphere, have been widely studied . It has been suggested that oxygen vacancies in transition metal oxides enhance N 2 adsorption, activation, and/or stabilization of reaction intermediates such as *NNH, thus promoting NRR activity . The formation of oxygen vacancies signifies exposure of coordinately unsaturated metal sites (i.e., Ti and Mo sites) for the adsorption of N 2 .…”

Section: Design Principles For Electrocatalystsmentioning

confidence: 99%

Atomic Modulation, Structural Design, and Systematic Optimization for Efficient Electrochemical Nitrogen Reduction

et al. 2020

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Ammonia (NH3) is a pivotal precursor in fertilizer production and a potential energy carrier. Currently, ammonia production worldwide relies on the traditional Haber–Bosch process, which consumes massive energy and has a large carbon footprint. Recently, electrochemical dinitrogen reduction to ammonia under ambient conditions has attracted considerable interest owing to its advantages of flexibility and environmental friendliness. However, the biggest challenge in dinitrogen electroreduction, i.e., the low efficiency and selectivity caused by poor specificity of electrocatalysts/electrolytic systems, still needs to be overcome. Although substantial progress has been made in recent years, acquiring most available electrocatalysts still relies on low efficiency trial‐and‐error methods. It is thus imperative to establish some critical guiding principles for nitrogen electroreduction toward a rational design and accelerated development of this field. Herein, a basic understanding of dinitrogen electroreduction processes and the inherent relationships between adsorbates and catalysts from fundamental theory are described, followed by an outline of the crucial principles for designing efficient electrocatalysts/electrocatalytic systems derived from a systematic evaluation of the latest significant achievements. Finally, the future research directions and prospects of this field are given, with a special emphasis on the opportunities available by following the guiding principles.

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“…[48] Han et al facilitated the NRR catalyst by engineering surface oxygen vacancies. [49] However, TiO 2 catalysts simultaneously achieving a large NH 3 yield with high Faradic efficiency are not available. Wu et al found that Fe could act effectively as a dopant to improve the NRR performances of TiO 2 nanoparticle for NRR significantly.…”

Section: Other Transition Metal Containing Catalystsmentioning

confidence: 99%

“…Huang et al fabricated a biomass-derived amorphous oxygen doped carbon nanosheet (OÀ CN) by treating with an annealing temperature of 900°C, showing high selectivity and stability with a yield of 20.15 μg h À 1 mg cat À 1 and a FE of 4.97% (Figure 10b, 10c). [102] Recently, Wu et al reported that oxygen-doped hollow carbon microtubes (OÀ KFCNTs) derived from natural kapok fibers Copyright 2019 Elsevier Ltd. [49] (d) Illustration of the fabrication of BVCÀ A and BVCÀ C NRR electrocatalysts (e) O 1s XPS spectra of BVCÀ A and BVCÀ C. (f) Raman spectra of BVCÀ A and BVCÀ C. Copyright 2019 Wiley-VCH. [150] (g) N 2 adsorption geometry on PCN with nitrogen vacancy; The charge density difference of the N 2 -adsorbed PCN with nitrogen vacancy; the yellow and blue isosurfaces represent charge accumulation and depletion in the space, respectively; Free energy diagram for NRR on NVs engineered PCN at equilibrium potential.…”

Section: Amorphizationmentioning

confidence: 99%

Recent Advances in Noble‐Metal‐Free Catalysts for Electrocatalytic Synthesis of Ammonia under Ambient Conditions

Xiang

Wang

et al. 2020

Chemistry An Asian Journal

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Ammonia is an essential chemical for producing fertilizers and energy carriers. However, the industrial Haber-Bosch process causes huge CO 2 emissions and energy waste. As a promising alternative for Haber-Bosch process, electrochemical synthesis of ammonia has drawn much attention. Catalysts, as a vital part of electrochemical nitrogen reduction reaction (NRR), have developed rapidly in recent years. Compared to noble-metal catalysts, noble-metal-free catalysts possess a low-cost advantage. In this review, noble-metalfree catalysts, including metal-based materials, metal organic frameworks (MOFs), MXenes, and metal-free materials, are summarized. In addition, effective design strategies are discussed, along with the main problems and some potential directions of noble-metal-free NRR catalysts. 2. Advances in Noble-Metal-Free Catalysts for Electrocatalytic N 2 Reduction Recently, although noble metal catalysts have better catalytic performance in NRR, researchers have paid more attention to the utilization of resource-rich elements in the earth, including iron, molybdenum, carbon, nitrogen, boron and other nonnoble elements, in order to reduce costs and improve the [a

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Activated TiO2 with tuned vacancy for efficient electrochemical nitrogen reduction

Cited by 231 publications

References 45 publications

Visible-Light Activation of Photocatalytic for Reduction of Nitrogen to Ammonia by Introducing Impurity Defect Levels into Nanocrystalline Diamond

Visible-Light Activation of Photocatalytic for Reduction of Nitrogen to Ammonia by Introducing Impurity Defect Levels into Nanocrystalline Diamond

Atomic Modulation, Structural Design, and Systematic Optimization for Efficient Electrochemical Nitrogen Reduction

Recent Advances in Noble‐Metal‐Free Catalysts for Electrocatalytic Synthesis of Ammonia under Ambient Conditions

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