Science Bulletin
·
2016
·
IF 0
Xiaoping Liu,Hao Qin,Weiliu Fan
Band offset is a dominant factor affecting the photocatalytic performance of heterostructure photocatalysts . Therefore, controlling the band gap structure of semiconductors is a key challenge in the development of efficient photocatalysts. We used a typical in situ-method to prepare diverse graphite-phase carbon nitride (g-C 3 N 4 ) samples from melamine , thiourea , and a mixture thereof, and found that they exhibited band gaps between 2.3–2.8 eV. From UV–Vis spectra and X-ray photoelectron spectroscopy measurements, we determined that the g-C 3 N 4 samples exhibited different band gap values and valence band positions. On this basis, we constructed g-C 3 N 4 /m-LaVO 4 heterojunctions with different band offsets. UV–Vis spectra and X-ray photoelectron spectroscopy measurements revealed that the valence band offsets (VBOs) of the different heterojunctions were similar, but their conduction band offsets (CBOs) were significantly different. Photocatalytic experiments revealed that the reaction rate was enhanced with an increase in the CBO value. Furthermore, the three-phase g-C 3 N 4 /g-C 3 N 4 /m-LaVO4 heterojunction composed of m-LaVO4 and mixed g-C 3 N 4 showed the highest photocatalytic activity , which was mainly due to the construction of a multilevel structure. This work investigates the influence of the band offset on heterojunction photoelectrochemical properties and provides a new strategy to improve the photocatalytic activity by constructing multilevel structures.
研究领域:
材料科学
·
光催化
✓ 已验证
产品关联
DOI
Nanoscale Advances
·
2021
·Vol. 3
·期 15
·4519-4527
·
IF 4.553
Pingping Wu,Jingxia Wang,Lei Jiang
Monitoring and post-processing of organic solvents are important for environmental protection. Challenges remain in the development of a universal material which can detect any solvent with a large stopband shift and show excellent stability. Herein, we demonstrate a poly 3,4-ethylenedioxythiophene inverse opal (PEDOT-IO) with a large stopband shift toward various solvents based on the insolubility/superoleophilicity properties. The PEDOT-IO film was fabricated by the potentiostatic polymerization of 3,4-ethylene dioxythiophene using a three-electrode system, infiltrating the interstices of the photonic crystal template with PEDOT and subsequently removing the template. The surface of the PEDOT-IO film presented a composite structure: interconnected pores and hollow shells. When the solvent was introduced into the voids of PEDOT-IO film, the effective refractive index (n) of the whole sample increased due to the replacement of air with the solvent, and the pores and hollow shells showed different degrees of swelling. The synergistic effect of increased n and volume expansion contributed to a large redshift of the stopband of the PEDOT-IO film. PEDOT-IO film exhibited excellent resistance to various solvents and high/low temperature. This work further enriches the application of conductive polymers in solvent-responsive PC sensors and provides a novel means of creating PC-based optical materials and devices.
研究领域:
材料科学
·
环境科学
·
光学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF SOLID STATE CHEMISTRY
·
2014
·
IF 2.2
Zhenlong Zhang,Jichun Zhu,Shengjun Li,Yanli Mao
SrTiO 3 /Bi 2 O 3 heterojunction semiconductor was prepared and characterized by X-ray diffraction, UV–vis absorption spectrum , and scanning electron microscope, surface photovoltage spectroscopy, and photoluminescence spectroscopy. The surface photovoltage spectra indicate that the separation efficiency of photoinduced charges for SrTiO 3 /Bi 2 O 3 was enhanced compared with that of SrTiO 3 or Bi 2 O 3 . The energy band diagram of SrTiO 3 /Bi 2 O 3 heterojunction was directly determined with X-ray photoelectron spectroscopy, and the conduction band offset between SrTiO 3 and Bi 2 O 3 was quantified to be 0.28±0.03 eV. The photoluminescence spectra display that the recombination rate of photoinduced carriers for SrTiO 3 /Bi 2 O 3 decreases compared with that of SrTiO 3 or Bi 2 O 3 , which is mainly due to the energy levels matching between them. Therefore the enhanced separation efficiency of photoinduced charges is resulting from the energy difference between the conduction band edges of SrTiO 3 and Bi 2 O 3 .
研究领域:
材料科学
·
光催化
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2014
·Vol. 39
·期 9
·4198-4205
·
IF 2.93
Zhenlong Zhang,Jichun Zhu,Shengjun Li,Xiangyang Liu,Yanli Mao
In this paper, TiO 2 nanotube (TNT) arrays and (Cu 2 Sn) x /3 Zn 1− x S ( x = 0.75, 0.24, and 0.09) nanocrystals were prepared, and TiO 2 nanotubes (TNTs) were sensitized with (Cu 2 Sn) x /3 Zn 1− x S nanocrystals. Compared with the plain TNTs, (Cu 2 Sn) x /3 Zn 1− x S sensitized TNTs present an enhanced photoelectrochemical response. The photocurrent enhancement was characterized with the photocurrent ratio of (Cu 2 Sn) x /3 Zn 1− x S sensitized TNTs to plain TNTs, which were 1.50, 1.63, and 2.13 for (Cu 2 Sn) x /3 Zn 1− x S with the composition of x = 0.75, 0.24, and 0.09, respectively. To understand this phenomenon, the energy band alignments of TNTs and (Cu 2 Sn) x /3 Zn 1− x S were investigated, based on which the conduction band offsets (CBO) between TNTs and (Cu 2 Sn) x /3 Zn 1− x S were determined, which were 0.31, 0.47, and 0.63 eV for (Cu 2 Sn) x /3 Zn 1− x S with the composition of x = 0.75, 0.24, and 0.09, respectively. These results display that the photocurrent enhancement becomes large with the increase of CBO, which indicates that the enhanced photoelectrochemical response is mainly due to the energy level matching between TNTs and (Cu 2 Sn) x /3 Zn 1− x S, and the variation of enhancement is resulting from the change of CBO.
研究领域:
材料科学
·
光催化
·
半导体纳米材料
·
能源材料
·
光电化学
✓ 已验证
DOI
高影响因子
ACS Nano
·
2015
·
IF 12.881
Shuang Jiao,Qing Shen,Iván Mora-Seró,Jin Wang,Zhenxiao Pan,Ke Zhao,Yuki Kuga,Xinhua Zhong,Juan Bisquert
Even though previously reported CdTe/CdSe type-II core/shell QD sensitizers possess intrinsic superior optoelectronic properties (such as wide absorption range, fast charge separation, and slow charge recombination) in serving as light absorbers, the efficiency of the resultant solar cell is still limited by the relatively low photovoltage. To further enhance photovoltage and cell efficiency accordingly, ZnTe/CdSe type-II core/shell QDs with much larger conduction band (CB) offset in comparison with that of CdTe/CdSe (1.22 eV vs 0.27 eV) are adopted as sensitizers in the construction of quantum dot sensitized solar cells (QDSCs). The augment of band offset produces an increase of the charge accumulation across the QD/TiO2 interface under illumination and induces stronger dipole effects, therefore bringing forward an upward shift of the TiO2 CB edge after sensitization and resulting in enhancement of the photovoltage of the resultant cell devices. The variation of relative chemical capacitance, Cμ, between ZnTe/CdSe and reference CdTe/CdSe cells extracted from impedance spectroscopy (IS) characterization under dark and illumination conditions clearly demonstrates that, under light irradiation conditions, the sensitization of ZnTe/CdSe QDs upshifts the CB edge of TiO2 by the level of ∼50 mV related to that in the reference cell and results in the enhancement of Voc of the corresponding cell devices. In addition, charge extraction measurements have also confirmed the photovoltage enhancement in the ZnTe/CdSe cell related to reference CdTe/CdSe cell. Furthermore, transient grating (TG) measurements have revealed a faster electron injection rate for the ZnTe/CdSe-based QDSCs in comparison with the CdSe cells. The resultant ZnTe/CdSe QD-based QDSCs exhibit a champion power conversion efficiency of 7.17% and a certified efficiency of 6.82% under AM 1.5G full one sun illumination, which is, as far as we know, one of the highest efficiencies for liquid-junction QDSCs.
研究领域:
材料科学
·
纳米技术
·
太阳能
·
光伏
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）