Abstract It is highly desirable to design an efficient photocatalysis system via manipulating electrons migration pathways for optimal hydrogen production from water splitting. Herein, flower-like MoSe2 has been employed as the co-catalyst to couple with cubic CdS nanoparticles for the in-situ construction of MoSe2/CdS heterojunction photocatalysts. Experimental investigations suggest that the photogenerated electrons can transfer across a space charge region between the MoSe2/CdS through the S-Mo-Se bonding, resulting in faster charge carriers separation and hence more long-lived electrons to participate in the hydrogen evolution reaction (HER). These insights are also supported by density functional theory (DFT)-based theoretical calculation. The dynamics of the photo-excited electrons was also investigated by ultrafast transient absorption spectroscopy. Furthermore, MoSe2 can afford more active sites for absorbing the protons for H2-evolution reactions, thereby accelerating the sluggish hydrogen evolution kinetics. Therefore, under visible-light irradiation, a remarkably enhanced photocatalytic H2 generation has been achieved in the MoSe2/CdS heterojunction (4.7 mmol·g-1·h-1) compared to mechanically mixed sample (3.3 mmol·g-1·h-1) and Pt-decorated CdS (1.3 mmol·g-1·h-1). The external quantum efficiency of the MoSe2/CdS heterojunction toward HER has been determined to be 15.6% at 450 nm. This work not only provides a rational design for utilizing abundant elements to develop high-performance photocatalysts, but also pave the way to understand the photogenerated carriers transfer dynamics.

中文翻译：

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对 MoSe2/CdS 异质结中电荷载流子动力学的机理洞察，以促进光催化析氢

摘要 非常需要通过操纵电子迁移途径来设计有效的光催化系统，以优化水分解制氢。在此，花状 MoSe2 作为助催化剂与立方 CdS 纳米粒子偶联，用于原位构建 MoSe2/CdS 异质结光催化剂。实验研究表明，光生电子可以通过 S-Mo-Se 键跨 MoSe2/CdS 之间的空间电荷区域转移，从而导致更快的电荷载流子分离，从而使更多长寿命电子参与析氢反应（HER ）。这些见解也得到了基于密度泛函理论 (DFT) 的理论计算的支持。还通过超快瞬态吸收光谱研究了光激发电子的动力学。此外，MoSe2 可以提供更多的活性位点来吸收 H2 析出反应的质子，从而加速缓慢的析氢动力学。因此，在可见光照射下，与机械混合样品（3.3 mmol·g-1·h-1）相比，MoSe2/CdS异质结（4.7 mmol·g-1·h-1）实现了显着增强的光催化H2生成。 1) 和 Pt 修饰的 CdS (1.3 mmol·g-1·h-1)。MoSe2/CdS 异质结对 HER 的外部量子效率在 450 nm 处已确定为 15.6%。这项工作不仅为利用丰富的元素开发高性能光催化剂提供了合理的设计，