TiO2 as an interfacial-charge-transfer-bridge to construct eosin Y-mediated direct Z-scheme electron transfer over a Co9S8 quantum dot/TiO2 photocatalyst

Hao, Xuqiang; Guo, Qingjie; Li, Mei; Jin, Zhiliang; Wang, Yicong

doi:10.1039/d0cy00893a

Cited by 50 publications

(35 citation statements)

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“…It's a pity that the low efficiency of converting solar energy into hydrogen energy because of the rapid recombination of photoexciton and low light utilization limited the application of photocatalyst. [7][8][9][10] For this purpose, multifarious strategies were used to improve the performance of photocatalysts, such as cocatalyst loading, defect begetting and heterostructure construction et al [11][12][13] Particularly, on account of the spatial separation of photo-carriers feature of heterojunction photocatalysts and have attracted tremendous attention. [14] Type-II, p-n and Z-scheme heterojunctions are widely used in the field of photocatalysis.…”

Section: Introductionmentioning

confidence: 99%

Zn‐Vacancy Engineered S‐Scheme ZnCdS/ZnS Photocatalyst for Highly Efficient Photocatalytic H₂ Evolution

2021

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Vacancy defects engineering is a valid strategy to enhance the separation efficiency of photo-generated charges. Herein, a zinc vacancy mediated S-scheme ZnCdS/ZnS composite derived from ZnCdS/MOF-5 was constructed in-situ through the sacrificial reagent of Na 2 S/Na 2 SO 3 aqueous solution in visiblelight irradiation. The MOF-5 converted to ZnS (ZnSÀ V Zn ) with abundant zinc vacancies which were proved by the XPS and PL results. ZnSÀ V Zn has two-photon absorption performance, which immensely enhanced the visible light absorption capacity for the photocatalysts. The photo-generated electrons of ZnSÀ V Zn on the Zn-vacancy defect would regroup with the holes in the valence band (VB) of ZnCdS via ohmic contact which is induced by Zn-vacancy defects. Therefore, the photoexciton of ZnCdS can be able to separate effectively and eliminate the useless electrons and holes. The ZnCdS/ZnS(20) sample revealed an outstanding photocatalytic hydrogen generation rate of 12.31 mmol h À 1 g À 1 with a turnover number (TON) of 64.61, which is about 82.06 and 21.98 times greater than that of neat ZnSÀ V Zn and ZnCdS. This work gives an insight into the design of the zinc vacancy-engineered S-scheme photocatalyst of ZnCdS/ZnS for highly efficient photocatalysis.

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Section: Introductionmentioning

confidence: 99%

Zn‐Vacancy Engineered S‐Scheme ZnCdS/ZnS Photocatalyst for Highly Efficient Photocatalytic H₂ Evolution

2021

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“…Charge transfer in photocatalytic reaction mechanism was further explored by comparing the migration of binding energy of each element in pure NiS2, bare MoSe2 and complex 43 . The upper electron spectrum corresponds to the elements in pure matter in Fig.…”

Section: X-ray Photoelectron Spectroscopymentioning

confidence: 99%

“…Stronger light absorption was more favorable for photocatalytic activity 46 . Through the Tauc equation (αhv = A(hv − Eg) 1/2 ), the direct band gap of two narrow band gap semiconductor materials was obtained based on the tangent line of (αhν) 2 to hν curve (where α was the absorption coefficient and hν was the photon energy) 43,47 .…”

Section: Optical Propertiesmentioning

confidence: 99%

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High Efficiency Electron Transfer Realized over NiS2/MoSe2 S-Scheme Heterojunction in Photocatalytic Hydrogen Evolution

刘阳¹,

郝旭强²,

胡海强³

et al. 2020

Acta Physico Chimica Sinica

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S-scheme heterojunction is a major breakthrough in the field of photocatalysis. In this study, NiS2 and MoSe2 were prepared by a typical solvothermal method, and compounded by an in situ growth method to construct an S-scheme heterojunction. The obtained composite showed excellent performance in photocatalytic hydrogen evolution; the hydrogen production rate was approximately 7 mmol•h −1 •g −1 , which was 2.05 times and 2.44 times those of pure NiS2 and MoSe2, respectively. Through a series of characterizations, it was found that NiS2 and MoSe2 coupling can enhance the light absorption intensity, which is vital for the light reaction system. The efficiency of electron-hole pair separation is also among the important factors restricting photocatalytic reactions. Compared with pure NiS2 and MoSe2, NiS2/MoSe2 exhibited a higher photocurrent density, lower cathode current, and lower electrochemical impedance, which proves that the NiS2/MoSe2 complex can effectively promote photogenerated electron transfer. Simultaneously, the lower emission intensity of fluorescence indicated effective inhibition of electron-hole recombination in the NiS2/MoSe2 complex, which is favorable for the photocatalytic hydrogen evolution reaction. Further, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that MoSe2 is an amorphous sample surrounded by the NiS2 nanomicrosphere, which greatly increased the contact area between the two, thus increasing the active site of the reaction. Secondly, as a photosensitizer, Eosin Y (EY) effectively enhanced the absorption of light by the catalyst in the photoreaction system. Meanwhile, during sensitization, electrons were provided to the catalyst, which effectively improved the photocatalytic reaction efficiency. The establishment of S-scheme heterojunctions contributed to improving the redox capacity of the reaction system and was the most important link in the photocatalytic hydrogen reduction of aquatic products. It was also the main reason for the improvement of the hydrogen evolution effect in this study. The locations of the conduction band and valence band of NiS2 and MoSe2 were determined by Mott-Schottky plots and photon energy curves, and further proved the establishment of the S-scheme heterojunction. This work provides a new reference for studying the S-scheme heterojunction to effectively improve the photocatalytic hydrogen production efficiency.

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“…In the past few decades, though, there have been great achievements in this field, the low efficiency of photogenerated charges separation in photocatalysts still is deemed to be the most vital factor limiting its practical application. Therefore, various strategies have been undertaken to improve the charge separation efficiency of photocatalysis in solar water splitting, among which, the construction of heterojunctions (p‐n heterojunction, [10–12] S‐scheme heterojunction, [13–16] direct type‐II heterojunction [17] etc.) shed profound light.…”

Section: Introductionmentioning

confidence: 99%

Pyramidal CdS Polyhedron Modified with NiAl LDH to Form S‐scheme Heterojunction for Efficient Photocatalytic Hydrogen Evolution

2021

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The construction of a stable and efficient photocatalyst plays an important role in the photocatalytic hydrogen evolution reaction of water splitting under visible light. In this work, both the pyramidal CdS polyhedron and NiAl LDH nanosheets were prepared by the hydrothermal method. Then, the CdS/NiAl LDH composite photocatalyst was successfully synthesized by physical mixing CdS and NiAl LDH. The best‐performing CdS/NiAl LDH photocatalyst shows out maximum H2‐production activity, which is about 6.31 times higher than pristine CdS. The loading of NiAl LDH nanosheets on the surface of pyramidal CdS polyhedron were verified by the XRD and the TEM characterization. The UV‐vis DRS indicated that the CdS/NiAl LDH composite photocatalyst was employed with distinct light absorption capacity compared with pristine CdS and pure NiAl LDH. Moreover, the CdS/NiAl LDH photocatalyst has efficient photon‐generated carriers separation capability. The outstanding photocatalytic H2 production of CdS/NiAl LDH profit from both morphological control and the formation of an S‐scheme heterojunction. Besides eliminating useless electrons and holes, the S‐scheme process could also provide more electrons to participate in photocatalytic H2 production.

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TiO₂ as an interfacial-charge-transfer-bridge to construct eosin Y-mediated direct Z-scheme electron transfer over a Co₉S₈ quantum dot/TiO₂ photocatalyst

Abstract: A novel eosin Y-mediated Z-scheme Co9S8 QDs/TiO2 photocatalytic system was constructed and a high AQE of 37.4% is obtained at 470 nm for 20%Co9S8/TiO2 heterojunction.

Cited by 50 publications

References 76 publications

Zn‐Vacancy Engineered S‐Scheme ZnCdS/ZnS Photocatalyst for Highly Efficient Photocatalytic H₂ Evolution

Zn‐Vacancy Engineered S‐Scheme ZnCdS/ZnS Photocatalyst for Highly Efficient Photocatalytic H₂ Evolution

High Efficiency Electron Transfer Realized over NiS<sub>2</sub>/MoSe<sub>2</sub> S-Scheme Heterojunction in Photocatalytic Hydrogen Evolution

Pyramidal CdS Polyhedron Modified with NiAl LDH to Form S‐scheme Heterojunction for Efficient Photocatalytic Hydrogen Evolution

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TiO2 as an interfacial-charge-transfer-bridge to construct eosin Y-mediated direct Z-scheme electron transfer over a Co9S8 quantum dot/TiO2 photocatalyst

Abstract: A novel eosin Y-mediated Z-scheme Co9S8 QDs/TiO2 photocatalytic system was constructed and a high AQE of 37.4% is obtained at 470 nm for 20%Co9S8/TiO2 heterojunction.

Cited by 50 publications

References 76 publications

Zn‐Vacancy Engineered S‐Scheme ZnCdS/ZnS Photocatalyst for Highly Efficient Photocatalytic H2 Evolution

Zn‐Vacancy Engineered S‐Scheme ZnCdS/ZnS Photocatalyst for Highly Efficient Photocatalytic H2 Evolution

High Efficiency Electron Transfer Realized over NiS<sub>2</sub>/MoSe<sub>2</sub> S-Scheme Heterojunction in Photocatalytic Hydrogen Evolution

Pyramidal CdS Polyhedron Modified with NiAl LDH to Form S‐scheme Heterojunction for Efficient Photocatalytic Hydrogen Evolution

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TiO₂ as an interfacial-charge-transfer-bridge to construct eosin Y-mediated direct Z-scheme electron transfer over a Co₉S₈ quantum dot/TiO₂ photocatalyst

Zn‐Vacancy Engineered S‐Scheme ZnCdS/ZnS Photocatalyst for Highly Efficient Photocatalytic H₂ Evolution

Zn‐Vacancy Engineered S‐Scheme ZnCdS/ZnS Photocatalyst for Highly Efficient Photocatalytic H₂ Evolution