Preparation of Ni 2 P on twinned Zn 0.5 Cd 0.5 S nanocrystals for high-efficient photocatalytic hydrogen production
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Ó Indian Academy of Sciences Sadhana (0123456789().,-volV)FT3](0123456 789().,-volV)
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Preparation of Ni2P on twinned Zn0.5Cd0.5S nanocrystals for highefficient photocatalytic hydrogen production XIAOPENG ZHOU, LINXIN YIN, KAIQING DAI, XIANGYANG GAO, YANAN FENG, YAFEI ZHAO* and BING ZHANG School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, People’s Republic of China E-mail: [email protected] MS received 16 July 2019; revised 17 September 2019; accepted 23 September 2019
Abstract. Developing efficient non-precious metal semiconductor photocatalysts is highly desirable for photocatalytically splitting water. In this work, the composite of the nanocrystal twinned Zn0.5Cd0.5S (ZCS) solid solution decorated with highly dispersed Ni2P nanoparticles was successfully formed by in situ growth method, and it exhibited remarkable photocatalytic hydrogen production activity of visible light. A high rate of hydrogen production of 30473 lmol h-1 g-1 was achieved, and the apparent quantum yield (AQY) was as high as 83.5% at 420 nm. Moreover, the sample could maintain outstanding photocatalytic hydrogenation activity after 4-cycle continuous catalytic process. The unique nano-twinned structure of ZCS and synergistic effects between the Ni2P and the twinned ZCS are responsible for the dramatically improved catalytic activities of photocatalysts composite. Keywords. photocatalysts; Ni2P-Zn0.5Cd0.5S; hydrogen production; water splitting.
1. Introduction Hydrogen energy has been widely recognized as an effective substitute to fossil fuels for its cleanliness and high-energy density.1 Photocatalytic hydrogen evolution, which uses solar power to produce hydrogen efficiently, is a promising hydrogen production strategy.2 Since the discovery of photocatalytic splitting water for hydrogen production with TiO2, the development of new semiconductor catalysts presented an accelerating trend.3 As is well known, photocatalytic activity is determined by the efficiency of transport and separation of electrons and holes generated by light, which greatly depends on the band energy levels and the microcrystal structure of the catalysts.4 Therefore, it is highly desirable to refine the microstructure and reduce the band gap energy of semiconductor photocatalysts, which is advantageous for not only the separation of photoelectrons and holes, but also for the transport of holes.5 In the past decades, various semiconductors were discovered, such as oxides, metal sulfides and oxynitrides,6–9 which have been identified as valid catalysts
for photocatalytic hydrogen production.10 Among them, cadmium sulfide (CdS) has gained extensive attention because of its relatively narrow band gap of 2.42 eV, which is more easily responsive for visiblelight and more negative than the redox potential of H?/H2.11 However, the practical application of CdS is limited due to its low apparent quantum yield resulting from rapid electron recombination and severe photocorrosion. To solve these problems, the construction of ternary metal
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