Oxygen Vacancy Induced Band-Gap Narrowing and Enhanced Visible Light Photocatalytic Activity of ZnO

Wang, Junpeng; Wang, Zeyan; Huang, Baibiao; Ma, Yandong; Liu, Yuanyuan; Qin, Xiaoyan; Zhang, Xiaoyang; Dai, Ying

doi:10.1021/am300835p

Cited by 1,297 publications

(690 citation statements)

References 38 publications

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“…Hererin, the LP is attributed to the Zn-O bonds for the wurtzite structure and the HP is usually attributed to chemisorbed oxygen. The MP is associated with O 2-in the oxygen-deficient regions with the matrix of ZnO, and the intensity of MP is related to the variations in concentration of oxygen vacancies [29]. From the figures, we can notice that the ZnO NRs without annealing displays a large number of oxygen vacancies.…”

Section: Resultsmentioning

confidence: 91%

High-performance ultraviolet-visible tunable perovskite photodetector based on solar cell structure

Xue

Zhou

et al. 2017

Sci. China Mater.

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An ultraviolet (UV)-visible tunable photodetector based on ZnO nanorod arrays (NAs)/perovskite heterojunction solar cell structures is presented, in which the ZnO NAs are prepared using the hydrothermal method and annealed in different atmospheres. Based on solar cell structure perovskite photodetectors, it exhibited highly repeatable and stable photoelectric response characteristics. In addition, the devices with ZnO NAs annealed in a vacuum showed a high responsivity of about 10 14 cm Hz 1/2 W −1 in the visible region, whereas the devices with ZnO NAs annealed in air exhibited good detectivity in the UV region, especially at around 350 nm. Furthermore, when the annealing atmosphere of the ZnO nanorods was changed from vacuum to air, the dominant detection region of the photodetectors was altered from the visible to the ultraviolet region. These results enable potential applications of the ZnO NAs/perovskite photodetectors in ultraviolet and visible regions.

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Section: Resultsmentioning

confidence: 91%

High-performance ultraviolet-visible tunable perovskite photodetector based on solar cell structure

Xue

Zhou

et al. 2017

Sci. China Mater.

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“…The peak O2 at 531.3 eV corresponds to the defects with low oxygen and the peak O3 can be attributed to adsorbed water at or near the surface. 21 The high relative intensity of peak O2 indicates the large amount of defects such as oxygen vacancies at the surface. On the other hand, recent research implies that amorphous structure is commensurate with crystalline materials in supercapacitors owing to the similar reason.…”

Section: Electrochemical Measurementsmentioning

confidence: 99%

Integrating large specific surface area and high conductivity in hydrogenated NiCo2O4 double-shell hollow spheres to improve supercapacitors

et al. 2015

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Increasing specific surface area and electrical conductivity are two crucial ways to improve the capacitive performance of electrode materials. Nanostructure usually enlarges the former but reduces the later; thus, it is still a great challenge to overcome such contradiction. Here, we report hydrogenated NiCo 2 O 4 double-shell hollow spheres, combining large specific surface area and high conductivity to improve the capacitive performance of supercapacitors. The specific surface area of NiCo 2 O 4 hollow spheres, fabricated via programmed coating of carbon spheres, was enlarged 50% (from 76.6 to 115.2 m 2 g − 1 ) when their structure was transformed from single-shell to double-shell. Furthermore, activated carbon impedance measurements demonstrated that the low-temperature hydrogenation greatly decreased both the internal resistance and the Warburg impedance. Consequently, a specific capacitance increase of 462%, from 445 to 718 F g − 1 , was achieved at a current density of 1 A g − 1 .Underlying such great improvement, the evolution of chemical valence and defect states with co-increase of these two factors was explored through X-ray photoelectron spectroscopy. Moreover, a full cell combined with NiCo 2 O 4 and AC was assembled, and an energy density of 34.8 Wh kg − 1 was obtained at a power density of 464 W kg − 1 . NPG Asia Materials (2015) 7, e165; doi:10.1038/am.2015.11; published online 13 March 2015 INTRODUCTION Supercapacitors, also known as electrochemical capacitors, have attracted great attention because of their outstanding power density, long cycling life and fast charge/discharge ability. 1-3 These virtues make them remarkable candidates for the electrical sources of hybrid electric vehicles, for which strong explosiveness is highly desired. Principally, supercapacitors run according to ion adsorption (electrochemical double-layer capacitors) or fast Faradaic reactions (pseudocapacitors) mechanisms. Comparatively speaking, the former has low specific capacitance and hence hard to satisfy the growing demand of peak-power assistance in electric vehicles. 4 Thus, more and more attentions were focused on pseudocapacitive electrode materials because their energy density associated with Faradaic reactions is much larger than that of electrochemical double-layer capacitors. [5][6][7][8] To improve performances of pseudocapacitors, two crucial factors are usually considered for the electrode materials, they are large specific surface area and high conductivity for electrolyte ions and electrons. On the one hand, large specific surface area will provide more electroactive sites for the Faradaic reactions, and load more doublelayer charges. Along such idea, many kinds of nanomaterials, 9-11 especially hollow spheres, 12 have been developed to improve

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“…The higher concentration of oxygen vacancies causes narrowing of the energy band gap i.e., from 3.34 eV to 3.21 or 3.12 eV direct energy band gap [40]. The decrease in spin concentration on increasing sintering temperature is attributed to the reduction of defects and ordering of lattice structure by the filling up of the oxygen vacancies.…”

Section: Epr Spectroscopymentioning

confidence: 99%

Investigation of physical properties of screen printed nanosized ZnO films for optoelectronic applications

Zargar

Arora

Hafiz

2015

Eur. Phys. J. Appl. Phys.

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Abstract. Nanosized ZnO particles derived from chemical co-precipitation route were used for casting ZnO films by screen printing method followed by sintering at two different temperatures. The variation in structural, optical and electrical properties of these films with temperature have been investigated by XRD, SEM, FTIR, Raman, UV-VIS, EPR and four probe analytical techniques. XRD patterns of these films exhibit polycrystalline nature with hexagonal wurtzite structure and SEM images reveal the smooth, dense and without any cracks/damage porous surface morphology. Infrared transmission spectra shows peaks pertaining to Zn-O stretching modes and their multiphonon modes. While Raman spectra exhibited strong peaks of E 2 (high) phonon and overtone of surface phonon mode at 429 cm −1 and 1144 cm −1 respectively with weak components of LO and TO branches. The direct band gap energy of these films showed narrowing of band gap from 3.21 eV to 3.12 eV on increasing sintering temperature from 500 • C to 600 • C. DC conductivity measurements confirmed semiconducting behaviour and showed lowering of activation energy. EPR spectra showed single narrow line resonance signal of g-value ∼ 1.9469 due to oxygen vacancies which are produced during synthesis of ZnO nanoparticles by sol-gel process. These studies revealed that on increasing sintering temperature the crystallinity of the film improves with reduction in lattice deformations in these screen printed ZnO films.

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Oxygen Vacancy Induced Band-Gap Narrowing and Enhanced Visible Light Photocatalytic Activity of ZnO

Cited by 1,297 publications

References 38 publications

High-performance ultraviolet-visible tunable perovskite photodetector based on solar cell structure

High-performance ultraviolet-visible tunable perovskite photodetector based on solar cell structure

Integrating large specific surface area and high conductivity in hydrogenated NiCo2O4 double-shell hollow spheres to improve supercapacitors

Investigation of physical properties of screen printed nanosized ZnO films for optoelectronic applications

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