Bilayer MoSe2/HfS2 Nanocomposite as a Potential Visible-Light-Driven Z-Scheme Photocatalyst.

Biao Wang,Tie Yang,Peng Wang,Hong Chen,Guangzhao Wang,Xiaotian Wang,Hongkuan Yuan

doi:10.3390/nano9121706

Biao Wang, Tie Yang + Show 5 more

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https://doi.org/10.3390/nano9121706

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Abstract

Visible-light-driven photocatalytic overall water splitting is deemed to be an ideal way to generate clean and renewable energy. The direct Z-scheme photocatalytic systems, which can realize the effective separation of photoinduced carriers and possess outstanding redox ability, have attracted a huge amount of interest. In this work, we have studied the photocatalytic performance of the bilayer MoSe2/HfS2 van der Waals (vdW) heterojunction following the direct Z-scheme mechanism by employing the hybrid density functional theory. Our calculated results show that the HfS2 and MoSe2 single layers in this heterojunction are used for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. The charge transfer between the two layers brought about an internal electric field pointing from the MoSe2 layer to the HfS2 slab, which can accelerate the separation of the photoinduced electron–hole pairs and support the Z-scheme electron migration near the interface. Excitingly, the optical absorption intensity of the MoSe2/HfS2 heterojunction is enhanced in the visible and infrared region. As a result, these results reveal that the MoSe2/HfS2 heterojunction is a promising direct Z-scheme photocatalyst for photocatalytic overall water splitting.

Highlights

In order to set up a sustainable society, photocatalytic water splitting for hydrogen production has been deemed as an effective route to solve the problems of environmental pollution and energy shortage [1]
As shown in the picture of the projected band structure, the valence band maximum (VBM) of this heterostructure is mainly composed of the MoSe2 layer, while the conduction band minimum (CBM) is primarily made up of the HfS2 layer, which is in support of the separation of the photoinduced carriers
We have designed a MoSe2/HfS2 bilayer heterostructure and investigated its electronic and optical properties according to the direct Z-scheme mechanism by employing the hybrid density functional theory

Summary

Introduction

In order to set up a sustainable society, photocatalytic water splitting for hydrogen production has been deemed as an effective route to solve the problems of environmental pollution and energy shortage [1]. A majority of one-component photocatalysts, such as TiO2 and ZnO, can only utilize a small amount of the solar energy and the lifetimes of photoinduced electron–hole pairs in these materials are short, which leads to the problem that the photocatalytic efficiency is low and hampers their future applications [8,9]. The Z-scheme photocatalytic system is made up of three parts: Catalysts for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and the redox mediator for carrier migration [25]. According to this mechanism, the isolated components cannot accomplish overall water splitting, the combined systems can decompose water into hydrogen and oxygen, which can broaden the scope of the promising photocatalysts. The direct Z-scheme systems have been extensively studied [28,29,30,31,32]

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