<i>In situ</i>liquid cell transmission electron microscopy guiding the design of large-sized cocatalysts coupled with ultra-small photocatalysts for highly efficient energy harvesting

Zhong

et al. 2022

ACS Appl. Nano Mater.

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Small-sized particles are usually used as cocatalysts and anchored onto a large-sized photocatalyst for fast charge separation. However, the current problem for the design of photocatalysts is that a high loading of small-sized particles leads to full coverage of photocatalysts, resulting in the decrease of hydrogen production. Here, we propose a different way to construct photocatalytic systems. Large-scale carbon nanotubes with doped nitrogen (N-CNTs) are used to couple with TiO 2 quantum dots. The H 2 yield for our optimized photocatalytic system is ∼146 mmol/g. With further considering the light-induced thermal effect, the H 2 yield reaches up to ∼320.6 mmol/g. Electrochemical and spectroscopic data show that large-sized N-CNTs can offer abundant active sites to realize the rapid carrier separation for tremendously improved hydrogen production.

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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N-Doped Carbon Nanofibers Coupled with TiO₂ Quantum Dots for Photocatalytic Hydrogen Production

Zhong

et al. 2022

ACS Appl. Nano Mater.

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“…Photocatalysts are usually composed of two different types. − One of them is pure photocatalysts, such as TiO 2 , − ZnO, CdS, − C 3 N 4 , or perovskite materials, ,− and the other one is pure photocatalysts anchored with cocatalysts. − Pure photocatalysts can be used for photocatalytic H 2 evolution with or without sacrificial agents. However, they are subjected to fast charge recombination under light irradiation. , Therefore, the corresponding photocatalytic H 2 yield is usually low. ,− To improve efficient charge separation, cocatalysts are employed and loaded on pure photocatalysts. , These cocatalysts are usually used to receive photogenerated electrons, thus realizing charge separation for highly effective photocatalytic H 2 evolution. , For the second kind of photocatalysts, cocatalysts usually have small sizes, and they are decorated onto photocatalysts to construct photocatalytic systems.…”

Section: Introductionmentioning

confidence: 99%

Porous Carbon Aerogel Decorated with TiO₂ Quantum Dots for Highly Improved Photocatalytic H₂ Evolution

ACS Appl. Energy Mater.

Deng

et al. 2023

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The design of photocatalysts plays a central role in determining the photocatalytic H 2 yield. Here, we used a design strategy that is different from conventional methods to prepare our photocatalytic systems. Large porous carbon aerogels (CA) with rich surface areas were used to receive photogenerated electrons. TiO 2 quantum dots were used as photocatalysts and anchored on large porous CAs to form CA@TiO 2 systems. The H 2 yield of the optimized CA@TiO 2 composite is ∼2.1 mmol/g, ∼11 times higher than that of pure TiO 2 quantum dots. High-resolution X-ray photoelectron spectroscopy and high-angle annular dark-field scanning transmission electron microscopy demonstrate that the photogenerated electrons can be easily transferred from TiO 2 quantum dots to porous CAs. Thus, efficient charge separation can be realized for the succeeding highly efficient H 2 evolution. Our results here provide a different way from conventional methods to design photocatalytic systems with high H 2 yield.

“…These carbon emissions are mainly from the consumption of fossil fuels, such as coal and oil . The development of sustainable energy has been considered an effective way to reduce carbon emission and to realize carbon neutrality. , Photocatalytic water splitting to produce hydrogen is an ideal method to harvest the cleanest hydrogen energy that can potentially achieve zero carbon emissions. − Therefore, photocatalytic water splitting has been intensively investigated since the first attempt to prepare hydrogen energy using TiO 2 as a photocatalyst …”

Section: Introductionmentioning

confidence: 99%

Ultrathin CdS Nanosheets Grown on N-Doped Carbon Nanotubes with Encapsulated Cobalts for Highly Improved Visible-Light-Driven Hydrogen Production

ACS Appl. Energy Mater.

et al. 2022

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Cocatalysts in photocatalytic systems play an important role in achieving efficient charge separation. These cocatalysts usually have a small size and are generally anchored onto main catalysts. They are taken as active centers to receive photogenerated electrons for water splitting. However, their high loading concentration usually leads to the degradation of water splitting. Here, we present a different strategy for the design of the main catalyst and cocatalyst. We used small-sized ultrathin cadmium sulfide (CdS) nanosheets as the main catalysts and anchored them onto large-sized Ndoped carbon nanotubes with encapsulated cobalts. The photocatalytic hydrogen production of our optimized composite is ∼21.8 mmol/g, ∼3 times higher than that of pure CdS. Mechanism study shows that photoelectrons can be transferred from CdS to N-doped carbon nanotubes, thus achieving fast charge separation and efficient hydrogen production.