Chinese Academy of Sciences (CAS) Key Laboratory for Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience , National Center for Nanoscience and Technology , Beijing 100190 , PR China.
University of Chinese Academy of Sciences , Beijing 100049 , PR China.
Nano Lett. 2019 Feb 13;19(2):1234-1241. doi: 10.1021/acs.nanolett.8b04768. Epub 2019 Jan 29.
Dual-band-gap systems are promising for solar water splitting due to their excellent light-harvesting capability and high charge-separation efficiency. However, a fundamental understanding of interfacial charge-transfer behavior in the dual-band-gap configuration is still incomplete. Taking CdS/reduced graphene oxide (CdS/RGO) nanoheterojunctions as a model solar water splitting system, we attempt here to highlight the interaction-dependent interfacial charge-transfer behavior based on both experimental observations and theoretical calculations. Experimental evidence points to charge transfer at the CdS-RGO interface playing a dominant role in the photocatalytic hydrogen production activity. By tuning the degree of reduction of RGO, the interfacial interaction, and, thereby, the charge transfer can be controlled at the CdS-RGO interface. This observation is supported by theoretical analysis, where we find that the interfacial charge transfer is a balance between the effective single-electron- and hole-transfer probability and the surface free electron and hole concentration, both of which are related to the surface potential and tailored by interfacial interaction. This mechanism is applicable to all systems for solar water splitting, providing a useful guidance for the design and study of heterointerfaces for high-efficiency energy conversion.
双能带隙系统由于其优异的光捕获能力和高电荷分离效率，在太阳能分解水方面具有广阔的应用前景。然而，对于双能带隙结构中的界面电荷转移行为的基本理解仍然不完整。以 CdS/还原氧化石墨烯（CdS/RGO）纳米异质结作为模型太阳能分解水系统，我们试图基于实验观察和理论计算来强调基于相互作用的界面电荷转移行为。实验证据表明，CdS-RGO 界面处的电荷转移在光催化产氢活性中起着主导作用。通过调节 RGO 的还原程度，可以控制 CdS-RGO 界面处的界面相互作用和电荷转移。这一观察结果得到了理论分析的支持，我们发现界面电荷转移是有效单电子和空穴转移概率与表面自由电子和空穴浓度之间的平衡，这两个参数都与表面势相关，并可通过界面相互作用进行调整。该机制适用于所有太阳能分解水系统，为高效能量转换异质结的设计和研究提供了有用的指导。
