JOURNAL OF CATALYSIS
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2016
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IF 7.354
Fangfang Wu,Gang Liu,Xiaoxiang Xu
LaTiO 2 N has been considered a promising candidate for efficient photocatalytic water splitting. However, its photocatalytic activity is often hampered by the presence of structural defects and poor charge mobility. In this work, we introduced Ca into the crystal structure of LaTiO 2 N via a simple co-precipitation method and investigated the photocatalytic and photoelectrochemical properties for the full range solid solution La 1− x Ca x TiO 2+ y N 1−y (0 ⩽ x , y ⩽ 1). Our results show that incorporating Ca into LaTiO 2 N induces a strong structural shrinkage as well as a space group change from I mma to P nma around a middle doping point ( x = 0.5). The presence of Ca effectively boosts the photocatalytic oxygen production and aids photocurrent extraction for LaTiO 2 N. The best photocatalytic activity was achieved for sample La 0.3 Ca 0.7 TiO 2.7 N 0.3 with oxygen production rate ∼66.96 μmol/h under visible light illumination ( λ ⩾ 420 nm), corresponding to apparent quantum efficiency ∼3.13%. XPS analysis revealed a substantial reduction in surface Ti 3+ species and a removal of A-site cation segregation for samples containing Ca. Further photoelectrochemical analysis highlights the critical role of Ca in enhancing the charge mobility of LaTiO 2 N. The better photocatalytic performance of Ca-modified LaTiO 2 N can be understood as a result of defect removal, high charge mobility, and improved surface charge migration pathways that considerably prolong the lifetimes of photogenerated charges.
研究领域:
材料科学
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化学工程
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能源科学
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产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2022
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IF 24.319
Guoan Lin,Xiaoqin Sun,Xiaoxiang Xu
LaTiO 2 N is modified by Mg doping to construct solid solution series, i.e ., LaTi 1−x Mg x O 2+y N 1−y (0 ≤ x ≤ 0.5). This modification effectively decreases the defect concentration (particularly bulk Ti 3+ species and anion vacancies), increases the surface hydrophilicity, positively shifts the valence band top albeit it also enlarges the bandgap and induces Ti/Mg ordering when x ≥ 0.2. These competitive tensions render an optimal composition at LaTi 0.9 Mg 0.1 O 2+y N 1−y (x = 0.1) where both a low defect concentration and a disordered state of Ti/Mg can be reached, demonstrating much-improved photocarrier separation and exceptional photocatalytic activity with apparent quantum efficiency as high as 13.02 % at 420 ± 20 nm for O 2 -evolution. Overall water splitting (H 2 /O 2 molar ratio = 2/1) with good recycling stability has been realized by integrating LaTi 0.9 Mg 0.1 O 2+y N 1−y into a Z-scheme system. These findings justify the efficacy of Mg as a useful modulator to improve the photocatalytic performance of metal oxynitrides.
研究领域:
材料科学
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能源科学
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产品关联
DOI
高影响因子
ACS Catalysis
·
2023
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IF 12.9
Jinxing Yu,Li Shi,Ronghua Li,Jie Huang,Ran Wang,Zhuo Li,Cai Shen,Gang Liu,Yanbo Li,Xiaoxiang Xu
Overall water splitting (OWS), liberating H2 and O2 in a 2:1 ratio, based on powdery photocatalysts, represents a simple and cost-effective means for solar hydrogen production. For an efficient solar energy harvest, the use of OWS reactions should be operated using narrow-band gap semiconductors, which remains a great challenge. In this work, photocatalytic OWS reactions, operable up to 600 nm, have been achieved over a narrow-band gap semiconductor LaTiO2N with single-crystalline nanosheet morphology. These nanosheets, prepared via a topotactic route, are of a low concentration of Ti3+ defects whose locations are limited to the top surface of ∼1 nm thickness. Such a regulated Ti3+ distribution is essential for OWS reactions as it enables the accumulation of both photogenerated electrons and holes at the surface region simultaneously. Compared with conventional inactive LaTiO2N, LaTiO2N single-crystalline nanosheets can stably photocatalyze OWS reactions under visible light and simulated AM1.5G after being deposited with the RhCrOy cocatalyst and coated with a Ti oxyhydroxide layer. These findings provide a rational guideline to open up the OWS activity of narrow-band gap semiconductors by proper defect regulation.
研究领域:
材料科学
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能源化学
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产品关联
DOI
高影响因子
Advanced Energy Materials
·
2023
·Vol. 14
·期 6
·2302996
·
IF 27.8
Ran Wang,Hanna He,Li Shi,Dayue Du,Guoan Lin,Chuhong Zhang,Xiaoxiang Xu
LaTiO 2 N is a promising narrow-bandgap semiconductor photocatalyst that shows great promise for water redox reactions. However, its performance is often hindered by fast photocarrier recombination events. Herein, LaTiO 2 N mesoporous single crystals (MSCs) are successfully fabricated via a topotactic conversion route by using the Ruddlesden–Popper compound NaLaTiO 4 as the precursor. The LaTiO 2 N MSCs are characterized by high crystallinity, abundant mesopores, no grain boundaries (GBs), and exposure of (010) and (101) crystal facets. A facet-assisted photocarrier separation mechanism is identified for these LaTiO 2 N MSCs which contributes to the much better photocarrier separation than conventional counterparts. By loading proper cocatalysts, LaTiO 2 N MSCs serve as an efficient photocatalyst for water-splitting half-reactions and are capable of photocatalyzing overall water-splitting reactions, delivering an impressive apparent quantum efficiency (AQE) as high as 65.07% at 420 ± 20 nm for O 2 -evolution and a solar-to-hydrogen (STH) efficiency as high as 0.012% for solar-driven overall water splitting. These findings not only highlight the grain-boundary-free MSCs with peculiar crystal-facet exposure as highly active photocatalysts for particulate photocatalysis but also provide a rational design approach for developing efficient photocatalysts.
研究领域:
材料科学
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光催化
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能源转换
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产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2023
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IF 22.1
Lina Wang,Jinxing Yu,Zhuo Li,Xiaoxiang Xu
LaTiO 2 N is a promising photocatalyst for solar water splitting but is generally subject to a low activity due to inadequate separation of photocarriers (i.e . e - and h + ). Loading noble metal cocatalysts such as Pt often has limited improvements because of their Schottky-type interfaces with LaTiO 2 N, resulting in a deficient electron collection at the surface catalytic sites. In this work, TiN nanoparticles have been firmly anchored at the surface of mesoporous single-crystalline LaTiO 2 N. As opposed to Pt, TiN has an ohmic contact with LaTiO 2 N due to a comparable work function and the structurally matched heterointerfaces. Such a tight and ohmic connection enables TiN to readily collect electrons from LaTiO 2 N, which in turn substantially improves the photocarrier separation and photocatalytic activity. These findings justify that TiN is an ideal relay for electron transfer between n-type semiconductors and noble metal cocatalysts which would otherwise be very difficult when the Schottky-type interfaces are formed.
研究领域:
材料科学
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光催化
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产品关联
DOI
高影响因子
Catalysis Science & Technology
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2025
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IF 4.2
Guoyu Xu,Yanan Chen,Peiling Lin,Zizhong Zhang,Tao Ji,Wenyue Su
Employing photocatalytic technology to transform CO2 into valuable fuels is considered a promising solution for addressing the exacerbated greenhouse effect and energy crisis. The development of photocatalysts featuring superior charge separation efficiency is pivotal for the widespread implementation of photocatalytic CO2 reduction technologies. Herein, zero-dimensional (0D) NixP nanoparticles are anchored onto two-dimensional (2D) LaTiO2N nanosheets by a photo-deposition method, and a NixP/LaTiO2N Schottky junction composite with excellent photocatalytic CO2 reduction performance is constructed. The optimal NixP/LaTiO2N composite achieves CO and CH4 yields of 9.39 and 4.15 μmol g−1 h−1, respectively, with the utilized photoelectron number (UPN) reaching 51.98 μmol g−1, which is approximately 9.7 times higher than that of LaTiO2N alone. The improved photocatalytic performance of the composites can be attributed to the formation of Schottky junctions, which effectively suppress the recombination of photogenerated carriers. This study provides a new idea for the development of 0D/2D Schottky junction photocatalysts.
研究领域:
材料科学
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环境科学
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能源科学
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产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
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2020
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IF 7.632
Guoan Lin,Xiaoxiang Xu
LaTiO2N has been considered as one of the most promising photocatalysts for solar energy conversion. Nevertheless, it generally has a poor photocatalytic activity under normal conditions, probably linked to severe structural distortions and various types of defects within this compound. Herein, we modified LaTiO2N by introducing Ba into its A site, that is, La0.8Ba0.2TiO2.2N0.8. The presence of Ba at the A site of LaTiO2N not only relaxes the structural distortions but also effectively inhibits defect formation (e.g. Ti3+ species) in LaTiO2N. Moreover, surface hydrophilicity of LaTiO2N is also improved by Ba modification. Photoelectrochemical analysis suggests that charge separation and transferring situation are ameliorated in Ba-modified LaTiO2N, and the valence band edge position is positively shifted. These factors are likely the reasons for the improved photocatalytic activity of La0.8Ba0.2TiO2.2N0.8 in water oxidation reactions.
研究领域:
材料科学
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光化学
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太阳能转换
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产品关联
DOI
高影响因子
Sustainable Energy & Fuels
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2023
·Vol. 7
·期 13
·3106-3115
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IF 5.6
Xiaoli Liu,Hezhou Huang,Xin Luo,Jianqiang Luo,Shujuan Liu,Yangbo Zhong,Yifan Zhang,Jiaojiao Ma,Feng-Qiang Xiong
The collection of photogenerated electrons is an essential part of the photoelectrochemical process on a semiconductor photoanode, which is often a bottleneck in a particulate photoanode. Herein, by ingeniously inserting a transparent electron-conducting ZnO nanorod array into a particulate LaTiO2N photoanode, bridges for electron transport are constructed between the nanoporous micron oxynitride particles and the AZO substrate, which improves the photocurrent from tens of μA cm−2 to 2.87 mA cm−2 at 1.23 VRHE. Furthermore, the electron transport in LaTiO2N particles is improved by increasing the electron carrier density of LaTiO2N micron particles. After a simple annealing treatment in an inert atmosphere at 713 °C, the electron carrier density of LaTiO2N micron particles is increased significantly as shown by EPR spectroscopy and Mott–Schottky analysis. The bulk resistance of an assembled particulate LaTiO2N photoanode is reduced with the increase of electron carrier density as shown by electrochemical impedance spectroscopy. The apparent charge separation efficiency on the photoanode assembled from annealed LaTiO2N micron particles is 1.6 times that assembled from as-prepared LaTiO2N micron particles, and the photocurrent for water oxidation is increased by 62%, reaching 4.66 mA cm−2. By improving electron collection, the conductive array insertion strategy together with particle carrier density optimization provides a method to increase the photocurrent by 2 orders of magnitude reaching the mA cm−2 level on a photoanode prepared from visible-light photocatalyst powder.
研究领域:
材料科学
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能源科学
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DOI
高影响因子
Catalysts
·
2026
·Vol. 16
·期 5
·436
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IF 4.5
Jinying Gao,Jiaxin Ji,Menglu Gao,Ting Yue,Meirong Huang
A-site defect engineering has been confirmed as an effective strategy for enhancing catalyst performance. Here, we develop a novel approach to synthesize A-site deficient perovskites by regulating alkali metal substitution and evaporation and further apply these materials for photocatalytic applications. Three representative perovskite oxides—La2Ti2O7, Na2La2Ti3O10, and Na0.5La0.5TiO3—were synthesized and then converted into perovskite oxynitrides with varying degrees of A-site defects (LaTiO2N, La0.67TiO2N, and La0.5TiO2N) through high-temperature ammonolysis. The photocatalytic water oxidation activity increased with the concentration of A-site defects, following the order: LaTiO2N < La0.67TiO2N < La0.5TiO2N, with a maximum enhancement of over 30 times. The performance boost was attributed to the facilitated interfacial electron transfer and improved charge separation caused by abundant A-site defects. These findings demonstrate that this strategy can successfully construct A-site deficient perovskites for highly efficient photocatalytic reactions, providing valuable insights for designing defect-engineered perovskite materials.
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DOI
高影响因子
ChemSusChem
·
2017
·Vol. 10
·期 5
·930-937
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IF 7.226
Feng-Qiang Xiong,Lipeng Wan,Yue Li,Tiju Thomas,Francis J. DiSalvo,Minghui Yang
Graphical Improving photocatalysts : Sufficient donor density in LaTiO 2 N photocatalysts is essential to generate an efficient internal electric field for charge separation and for high oxidizing power of the holes. On the basis of this understanding, LaTiO 2 N photocatalysts were modified to give a quantum efficiency for water oxidation of 25 % at 450 nm, which is higher than that of conventional LaTiO 2 N. LaTiO 2 N photocatalysts were prepared by thermal ammonolysis of flux-synthesized La 2 Ti 2 O 7 and La 2 TiO 5 , and were investigated for water oxidation. Though LaTiO 2 N derived from La 2 TiO 5 appears defect-free by UV/Vis/near-IR and electron paramagnetic resonance (EPR) spectroscopy, its performance is much lower than that of conventional La 2 Ti 2 O 7 -derived LaTiO 2 N with defects. It is shown by Mott–Schottky analysis that La 2 TiO 5 -derived LaTiO 2 N has significantly lower donor density; this can result in insufficient built-in electric field for the separation of photogenerated electrons and holes. The lower donor density is also consistent with the smaller difference between the Fermi level and the valence-band maximum, which accounts for a lower oxidative power of the holes. In light of this discovery, the donor density was increased substantially by introducing anion vacancies through annealing in Ar. This resulted in improved performance. The CoO x -assisted La 2 TiO 5 -derived LaTiO 2 N annealed at 713 °C has a higher quantum efficiency (25 %) at 450 nm than high-performance conventional CoO x /LaTiO 2 N (21 %).
研究领域:
材料科学
·
环境科学
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DOI
高影响因子
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