Efficient photocatalytic hydrogen evolution on single-crystalline metal selenide particles with suitable cocatalysts.

Shanshan Chen,Lihua Lin,Akira Yamakata,Tsuyoshi Takata,Mamiko Nakabayashi,Taro Yamada,Naoya Shibata,Zheng Wang,Junie Jhon M Vequizo,Kazunari Domen,Takashi Hisatomi

doi:10.1039/d0sc01167c

Abstract

It is important to improve the apparent quantum yields (AQYs) of narrow bandgap photocatalysts to achieve efficient H2 production. The present work demonstrates a particulate solid solution of zinc selenide and copper gallium selenide (denoted as ZnSe:CGSe) that evolves H2 efficiently and is responsive to visible light up to 725 nm. This material was synthesized using a flux-assisted method and was found to comprise single-crystalline tetrahedral particles. The coloading of Ni and Rh, Pt, Pd or Ru as cocatalysts further improved the photocatalytic H2 evolution rate over this photocatalyst. With the optimal coloading of a Ni–Ru composite cocatalyst, an AQY of 13.7% was obtained at 420 nm during a sacrificial H2 evolution reaction, representing the highest value yet reported for a photocatalyst with an absorption edge longer than 700 nm. The present study demonstrates that the preparation of single-crystalline particles and the rational assembly of composite cocatalysts are effective strategies that allow the efficient utilization of long wavelengths by metal selenide photocatalysts for solar fuel production.

Highlights

zinc selenide (ZnSe):copper gallium selenide (CGSe) solid solution was synthesized using a ux-assisted method in sealed evacuated quartz tubes, as described in the Electronic supplementary information (ESI).† The Ga/Cu and Zn/(Zn + Cu) molar ratios were xed at 2.0 and 0.5, respectively, because a ZnSe:CGSe solid solution with this composition has previously demonstrated high Z-scheme overall water splitting activity when used as a hydrogen evolution photocatalysts (HEPs).[11]
In the X-ray diffraction (XRD) pattern obtained from this material (Fig. 1b), the main diffraction peaks were located between those for standard ZnSe (ICSD #162755) and CuGa3Se5 (ICSD #181418) specimens, demonstrating the successful formation of a solid solution
The as-prepared ZnSe:CGSe specimen was composed of the transition phase of CuGaSe2 and CuGa3Se5.11,14 Analysis using the UV-vis diffuse re ectance spectrum (DRS; Fig. 1c) showed that the present ZnSe:CGSe specimen was a narrow band gap semiconductor with an absorption edge of 725 nm, similar to ZnSe:CGSe prepared using the traditional solid-state reaction method.[11]

Summary

Introduction

Metal selenides are narrow bandgap semiconductors with tunable electronic and band structures and have been widely applied, such as in solar cells, light-emitting diodes, photoelectrochemical devices and biomedical diagnostics.[1,2,3,4] Sunlight-driven water splitting using particulate photocatalysts is of vital importance in consideration that the produced hydrogen is an environmentally friendly and sustainable alternative to fossil fuels.[5,6,7,8,9] A prerequisite for efficient solar energy conversion is the development of photocatalytic systems that can utilize the wide wavelength range of the solar spectrum.[10] Metal selenide semiconductors are promising photocatalytic materials because they have narrow bandgaps and tunable band structures.[11,12]. (light absorption, charge transfer and catalytic conversion) so as to produce an efficient metal selenide photocatalyst. The strategies demonstrated are believed to have applications in other photocatalytic systems so as to achieve efficient solar fuel production

Results and discussion

Conclusions

Conflicts of interest