Elsevier

Applied Surface Science

Volume 481, 1 July 2019, Pages 795-801
Applied Surface Science

Full length article
Facile ultrasound-driven formation and deposition of few-layered MoS2 nanosheets on CdS for highly enhanced photocatalytic hydrogen evolution

https://doi.org/10.1016/j.apsusc.2019.03.176Get rights and content

Abstract

In this study, we reported a simple but effective ultrasound-driven route to form and deposit MoS2 onto CdS substrate, which was carried by ultrasonic irradiation in an ultrasonic cleaning bath. The ultrasonic irradiation of a suspension of CdS nanowires and (NH4)2MoS4 in an aqueous solution of ethanol for 30 min yielded a MoS2 nanosheets-deposited CdS composite (MoS2/CdS). The resulting MoS2/CdS has been shown to significantly enhance the photocatalytic performance for H2 evolution compared to pure CdS. Various characterization results reveal that the MoS2 nanosheets deposited on CdS by the ultrasound-driven route are short-range shaped, less ordered, few-layered, and close in contact with CdS, which are responsible for the enhanced H2 evolution performance. We believe that the present work opens up a new avenue for the fabrication of MoS2/sulphide used for efficient photocatalytic H2 evolution.

Graphical abstract

Ultrasonic irradiation of a suspension of CdS nanowires and (NH4)2MoS4 in an aqueous solution of ethanol yields a few-layered MoS2 nanosheets-deposited CdS composite, which exhibits efficient photocatalytic H2 evolution.

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Introduction

With the vast consumption of fossil fuels and the resulting environmental pollution, seeking an alternative, sustainable and clean energy source has become worldwide issues. Photocatalytic production of H2 from water splitting using a semiconductor photocatalyst is a promising and attractive approach in the conversion of solar energy to chemical energy, which offers a green and economical solution to the above problems. Since the first report that water splitting could be achieved on TiO2 electrodes by photoelectrocatalysis [1], a mass of semiconductor photocatalysts have been developed for photocatalytic H2 evolution reaction (HER) [[2], [3], [4], [5], [6], [7], [8]]. However, the photocatalytic activity and solar energy conversion efficiency of pure photocatalysts are extremely low, due to the high overpotential for H2 evolution, fast recombination of photogenerated charge carriers, and slow reaction kinetics of water splitting processes etc. [[9], [10], [11]]. Therefore, the surface modification with an appropriate cocatalyst has been applied to improve photocatalytic activity of host semiconductor photocatalysts. The appropriate cocatalyst can effectively hinder the recombination of electron-hole pairs photogenerated over the host semiconductor catalyst, lower the activation potentials for H2 evolution, and serve as the active sites for H2 generation [12,13]. As widely reported, loading a noble metal such as Pt, Pd, Au or Ru as a cocatalyst could be effective for photocatalytic HER with the above merits [12,14]. However, these noble metals are too scarce and expensive to be used in large scale. It is urgent to explore highly efficient and economical non-noble cocatalysts for photocatalytic HER.

Recently, MoS2 has attracted researcher's tremendous attention as cocatalyst [[15], [16], [17]], which exhibits excellent performance towards the photocatalytic hydrogen evolution reaction (HER) [[18], [19], [20], [21], [22], [23], [24]]. It was concluded from density functional calculations that MoS2 has the free binding energy close to zero for atomic hydrogen adsorption, which is comparable with that of Pt [25]. Meanwhile, both experiment and computation have well disclosed that the active S atoms located at exposed edges of MoS2 layers were active sites for H2 production [26]. In other words, MoS2 is expected to replace noble metals as an effective cocatalyst for the photocatalytic HER. Recently, a great number of MoS2-deposited CdS systems fabricated by the approaches such as impregnation-reduction, thermal decomposition, hydrothermal treatment, and photoreduction have been reported to greatly boost photocatalytic H2 evolution [[15], [16], [17], [18],20,21,[25], [26], [27], [28], [29], [30], [31]]. However, these approaches suffer from high-temperature, high-pressure, toxic chemical, or long term. Therefore, it is still an important issue to develop a simple, feasible, and environmentally friendly approach to the formation and deposition of MoS2 onto a host photocatalyst for efficient photocatalytic H2 evolution. Herein, we demonstrated a facile ultrasound-driven method for the formation and deposition of short-range shaped and few-layered MoS2 nanosheets on CdS nanowires (MoS2/CdS) with (NH4)2MoS4 as a precursor in an aqueous solution of ethanol. Upon visible light irradiation, the obtained MoS2/CdS has been shown to have a much higher activity for H2 production than pure CdS. Various characterization results revealed that the MoS2 nanosheets deposited on CdS nanowires by the ultrasound-driven route not only can promote electron transfer and inhibit the charge recombination, but also provide abundant coordinately unsaturated S atoms as active sites for H2 production. Moreover, the process of the ultrasound-driven formation and deposition of MoS2 on CdS nanowires is also briefly presented.

Section snippets

Preparation of CdS NWs

CdS nanowires were synthesized by a solvothermal method, as reported in previous research [32]. Briefly, Cd(NO3)2·4H2O (1.536 g) and CH4N2S (thiourea 1.136 g) were dissolved into ethylenediamine (40 ml). The mixture was then transferred into a Teflon-lined stainless-steel autoclave and maintained at 180 °C for 24 h. After cooling to room temperature, the yellow precipitates were collected by centrifugation, thoroughly washed with deionized water and absolute ethanol before dried in a vacuum

Results and discussion

Up to now, the ultrasound-driven method has been exploited not only for anchoring metallic nanoparticles (Ag, Au, Pd, and Pt) and metal oxides (e.g., MgO) onto the surfaces of various substrates such as silica spheres, titania, alumina, and polystyrene spheres, but also for synthesizing sulphides including ZnS, CdS, and MoS2 [33]. Recently, the ultrasound method was reported to fabricate graphene/MoS2 composites used for photocatalytic degradation of organic compounds [34]. In this work, we

Conclusions

In summary, the ultrasound-driven formation and deposition of short-range shaped and few-layered MoS2 nanosheets onto CdS nanowires have been successfully achieved in an ultrasonic cleaning bath with (NH4)2MoS4 as a precursor. The obtained MoS2/CdS exhibits a much higher photocatalytic activity than pure CdS for H2 evolution under visible light irradiation. The MoS2 nanosheets as a cocatalyst promote the photogenerated charge transfer across the intimate interfaces between the MoS2 and CdS, and

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (Grant No. 21673287).

References (47)

  • G. Swain et al.

    Coupling of crumpled-type novel MoS2 with CeO2 nanoparticles: anoble-metal-free p-n heterojunction composite for visible light photocatalytic H2 production

    ACS Omega

    (2017)
  • S. Zhang et al.

    MoS2 quantum dot growth induced by S vacancies in a ZnIn2S4 monolayer: atomic level heterostructure for photocatalytic hydrogen production

    ACS Nano

    (2018)
  • D.A. Reddy et al.

    Enhanced photocatalytic hydrogen evolution by integrating dual co-catalysts on heterophase CdS nano-junctions

    ACS Sustain. Chem. Eng.

    (2018)
  • D.A. Reddy et al.

    Multicomponent transition metal phosphides derived from layered double hydroxide double-shelled nanocages as an efficient non-precious co-catalyst for hydrogen production

    J. Mater. Chem. A

    (2016)
  • C. Chen et al.

    Catalysis of photooxidation reactions through transformation between Cu2+ and Cu+ in TiO2–Cu–MOF composites

    Chem. Commun.

    (2018)
  • F. Guo et al.

    Assembly of protonated mesoporous carbon nitrides with co-catalytic [Mo3S13]2−clusters for photocatalytic hydrogen production

    Chem. Commun.

    (2017)
  • J.H. Park et al.

    Hybrid metal–Cu2S nanostructures as efficient cocatalysts for photocatalytic hydrogen generation

    Chem. Commun.

    (2017)
  • S. Hong et al.

    Earth abundant transition metal-doped few-layered MoS2 nanosheets on CdS nanorods for ultra-efficient photocatalytic hydrogen production

    J. Mater. Chem. A

    (2017)
  • O. Stroyuk et al.

    Solar light harvesting with multinary metal chalcogenide nanocrystals

    Chem. Soc. Rev.

    (2018)
  • D.A. Reddy et al.

    Hydrazine-assisted formation of ultrathin MoS2 nanosheets for enhancing their co-catalytic activity in photocatalytic hydrogen evolution

    J. Mater. Chem. A

    (2017)
  • K. Chang et al.

    Targeted synthesis of 2H- and 1T-phase MoS2 monolayers for catalytic hydrogen evolution

    Adv. Mater.

    (2016)
  • J. Chen et al.

    One-pot synthesis of CdS nanocrystals hybridized with single-layer transition-metal dichalcogenide nanosheets for efficient photocatalytic hydrogen evolution

    Angew. Chem. Int. Ed.

    (2015)
  • X.L. Yin et al.

    MoS2/CdS nanosheets-on-nanorod heterostructure for highly efficient photocatalytic H2 generation under visible light irradiation

    ACS Appl. Mater. Interfaces

    (2016)
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