Advanced Energy Materials
·
2024
·
IF 24.4
Jinxing Yu,Jie Huang,Ran Wang,Elena Yu Konysheva,Gang Liu,Xiaoxiang Xu
SrNbO 2 N is a promising narrow-bandgap semiconductor for sunlight-driven water splitting but is generally subject to insufficient photocarrier separation and severe photocorrosion. Here, the targeted single-crystalline SrNbO 2 N nanobelts are passivated by consecutive annealing in O 2 and N 2 /NH 4 F to approach the right N/O ratio (1/2) and anion content (O + N = 60 at%). The passivation measures lead to both a low concentration (≈2.2 × 10 15 cm −3 ) of defects including V O , Nb 3+ , Nb 4+ for efficient photocarrier separation and unique fluorine-rich, nitrogen-poor surface with low surface energy for high stability against photocorrosion. Notably, the passivated SrNbO 2 N nanobelts deliver the highest values of photocurrent density of 4.5 mA cm −2 at 1.23 V versus RHE and stable photocatalytic (PC) Z-scheme overall water splitting activity of ≈10 µmol h −1 H 2 evolution under AM 1.5G illumination when used as photoanode materials for photoelectrochemical (PEC) water oxidation and the photocatalytic O 2 -evolution moiety, respectively. These findings provide not only an effective guideline to upgrade the activity and stability of SrNbO 2 N but also fresh mechanistic insights into the role of passivation measures.
研究领域:
材料科学
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能源化学
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光催化领域
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry A
·
2018
·Vol. 6
·期 23
·10947-10957
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IF 9.931
Xiaoqin Sun,Gang Liu,Xiaoxiang Xu
Although SrNbO2N has a promising band gap of ∼1.8 eV for solar water splitting, its photocatalytic activity is generally very poor under ordinary conditions, primarily due to high defect levels caused by synthetic procedures. In this work, we managed to control defect levels inside SrNbO2N by incorporating Mg into the structure, i.e. SrMgx/3Nb1−x/3O2+yN1−y (0 ≤ x ≤ 1). Strikingly, a number of important properties such as band gap value, defect level, nitrogen content and particle size can be tuned by varying the amounts of Mg in the structure. More importantly, efficient photocatalytic water oxidation into oxygen was realized using these Mg modified SrNbO2N. An apparent quantum efficiency (AQE) as high as 5.13% was reached at 420 ± 20 nm for SrMg0.2Nb0.8O2+yN1−y (x = 0.6), which stands as the highest AQE reported to date for SrNbO2N. Mott–Schottky and X-ray photoelectron spectroscopy analyses revealed the shift of valence band maximum of SrNbO2N in response to Mg uptake. Moreover, open-circuit voltage decay measurements confirmed a much prolonged charge lifetime in Mg modified SrNbO2N. Thus, Mg serves not only to tailor band edge positions but also to ameliorate charge separation conditions in SrNbO2N, both of which contribute to the superior photocatalytic activities.
研究领域:
材料科学
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能源化学
✓ 已验证
产品关联
DOI
高影响因子
Nano Energy
·
2022
·
IF 19.069
Lin Yang,Jinxing Yu,Qingyang Fu,Lulu Kong,Xiaoxiang Xu
Grain boundaries serve as an interception to the transportation of photo-generated charges (e - and h + ), severely undermining the photocatalytic performance. In this work, SrNbO 2 N porous single crystals (PSCs) free of grain boundaries have been synthesized, which deliver exceptionally high photocatalytic activity and stability for water oxidation reactions. The removal of grain boundaries warrants fast charge transportation, reducing the risks of charge recombination. The high porosity of PSCs supplies ample inner surface to carry out catalytic reactions . Deposited with a proper cocatalyst , SrNbO 2 N PSCs can photocatalyze water oxidation into O 2 with apparent quantum efficiency (AQE) as high as 5.64% at 420 ± 20 nm. The high activity is also exemplified by integrating SrNbO 2 N PSCs into a Z-scheme system which can split water into H 2 and O 2 in stoichiometry under simulated solar insolation. These findings not only prove that PSCs expedite charge migration, triggering a high activity for photocatalytic reactions, but also enliven more attention upon traditional materials that hold the potential for solar energy conversions.
研究领域:
材料科学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2017
·
IF 2.986
Yue Li,Feng-Qiang Xiong,Ruiling Ou,Lipeng Wan,Congling Yin,Ruxin Che,Minghui Yang
Highly crystalline (110) layered perovskite Sr 2 Nb 2 O 7 , (111) layered perovskite Sr 5 Nb 4 O 15 and complex perovskite Sr 4 Nb 2 O 9 were prepared by NaCl-KCl flux growth method from SrCO 3 and Nb 2 O 5 . This flux synthesis achieves single strontium niobate phase in contrast to mixed niobates from the solid state reaction with the same heating parameters. A little excess of Sr source was found to be required for the synthesis of Sr 5 Nb 4 O 15 and Sr 4 Nb 2 O 9 at elevated temperature due to slight evaporation. The three strontium niobates were converted to perovskite SrNbO 2 N via thermal ammonolysis under NH 3 flow at 900 °C. Post-wash treatment was performed to remove the byproduct SrO. This makes additional nanopores in SrNbO 2 N in the cases of Sr 5 Nb 4 O 15 and Sr 4 Nb 2 O 9 , and results in increasing surface areas of SrNbO 2 N with Sr:Nb ratios in the precursors (from 9.9 to 19.8 and 35.5 m 2 /g). On the other hand, the UV–Vis diffusion reflectance spectra reveal decreasing light absorption by defects in SrNbO 2 N in this order. This suggests fewer low-valent Nb defects in SrNbO 2 N prepared from precursor with higher Sr:Nb ratio. SrNbO 2 N prepared from Sr 4 Nb 2 O 9 would be advantageous for applications that require high surface area and low defect density of the material.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
Inorganic Chemistry Frontiers
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2020
·Vol. 7
·期 14
·2629-2636
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IF 5.958
Guoan Lin,Ran Wang,Tongcheng Cao,Liangxi Yuan,Xiaoxiang Xu
With an absorption edge as far as 690 nm, SrNbO2N holds great promise for solar energy conversion. However, very poor photocatalytic activity is generally seen for SrNbO2N, limiting its practical applications as a photocatalyst. In this work, SrNbO2N is modified by introducing Zr at B sites, i.e. SrNb1−xZrxO2+yN1−y (0 ≤ x ≤ 1), which are then investigated as photocatalysts for water oxidation reactions. Zr modification not only induces porous microstructures and inhibits the formation of Nb4+ defects, but it also ameliorates the surface hydrophilicity of SrNbO2N. Clear improvements in photocatalytic water oxidation have been realized after Zr modification and an apparent quantum efficiency of as high as 1.44% has been achieved. Further analysis of the band edge alignments suggests that Zr modification positively shifts the valence band edge of SrNbO2N, which favors water oxidation reactions.
研究领域:
材料科学
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光催化
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太阳能转换
✓ 已验证
产品关联
DOI
高影响因子
ENERGY & FUELS
·
2022
·
IF 4.654
Shuowen Wang,Yunfeng Bao,Yu Qi,Hai Zou,Shiwen Du,Xueshang Xin,Nengcong Yang,Chun Yang,Qing-lun Wang,Fuxiang Zhang
With a superior light-response ability and a high dielectric constant, the perovskite oxynitride SrNbO2N was expected to be an efficient photocatalyst for solar water splitting. However, a high defect density that formed during its preparation process had inhibited its charge separation and decreased the photocatalytic activity. In this work, SrNbO2N was modified through a high concentration doping of Zn2+ at the B site to inhibit its defect formation and promote its photocatalytic oxygen evolution performance. The defect formation in Sr(Nb2/3Zn1/3)O3–xNy (SNZON) is inhibited due to the sacrificial reduction of zinc ions during the nitridation process. Benefiting from the successful inhibition of defect formation and the promoted surface hydrophobicity, a remarkably promoted water oxidation activity was achieved on the as-obtained SNZON photocatalyst and the apparent quantum efficiency at 420 ± 10 nm reaches about 2.4%. This work may endow a new solution toward the preparation of low-defect oxynitride semiconductors with enhanced solar to chemical energy conversion efficiency.
研究领域:
材料科学
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光催化
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太阳能转换
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半导体物理
✓ 已验证
产品关联
DOI
高影响因子
Sustainable Energy & Fuels
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2020
·Vol. 4
·期 4
·1674-1680
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IF 5.503
Yingchen Yang,Zirui Lou,Weisheng Lei,Yichen Wang,Rong Liang,Chao Qin,Liping Zhu
Perovskite SrNbO2N particles were directly synthesized using a one-step thermal nitridation method with chloride flux and subsequently annealed under an inert Ar flow. By suitable adjustment of the flux synthesis parameters, including the nitridation temperature and the composition of the molten salt, preferable experimental conditions were found to suppress the formation of surface Nb defects and obtain samples with high crystallinity. The different SrNbO2N photoanodes were fabricated using the electrophoretic deposition (EPD) method followed by necking treatment. The SrNbO2N photoanode prepared using the optimum experimental conditions (nitridation temperature: 850 °C, a molar ratio of flux SrCl2 : KCl = 2 : 1) exhibited the highest photocurrent density of 2.0 mA cm−2 at 1.23 VRHE under simulated sunlight (AM 1.5G 100 mW cm−2) in a 1 M NaOH electrolyte. In comparison, the other highly defective SrNbO2N photoanodes demonstrated an unsatisfactory water oxidation performance, which demonstrates the necessity to reduce the destructive effect of defects in order to achieve a higher photocurrent density.
研究领域:
材料科学
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光电化学
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能源材料
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表面科学
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2018
·
IF 3.057
Wen-Bin Niu,Shi-Kuan Sun,Wei-Ming Guo,Shan-Lu Chen,Ming Lv,Hua-Tay Lin,Cheng-Yong Wang
The perovskite-structure group oxynitrides BaTaO 2 N and SrNbO 2 N, usually obtained by ammonolysis of the oxide precursors, were prepared by the reaction between the corresponding alkaline earth carbonate and tantalum nitride or niobium nitride in the flow of nitrogen. The chemical composition and particle morphology of the products were investigated as well as the phase path and reaction mechanism. It was found that the nearly single phase oxynitride phases formed at 1200–1300 °C, where the partial oxidation of nitrides and the absence of oxide impurities was achievable. The products were deficient in nitrogen content and formed with a fine particle size with the narrow size distribution.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）