Tuning Cu dopant of Zn0.5Cd0.5S nanocrystals enables high-performance photocatalytic H2 evolution from water splitting under visible-light irradiation. (August 2016)

• Record Type: Journal Article
• Authors: Mei, Zongwei; Zhang, Bingkai; Zheng, Jiaxin; Yuan, Sheng; Zhuo, Zengqing; Meng, Xianguang; Chen, Zonghai; Amine, Khalil; Yang, Wanli; Wang, Lin.-Wang; Wang, Wei; Wang, Shufeng; Gong, Qihuang; Li, Jun; Liu, Fu.-Sheng; Pan, Feng
• Is Part Of: Nano energy. Volume 26(2016:Aug.)
• Page Start: 405
• Page End: 416
• Publication Date: 2016-08
• Subjects: Cu dopant -- Zn0.5Cd0.5S -- Mechanism -- Photocatalytic H2 evolution -- Water splitting -- Visible light; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2016.05.051
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Cu-doping into Zn1−x Cdx S can greatly enhance the photocatalytic H2 evolution from water splitting under visible-light irradiation. However, it is still controversial for how the Cu-dopant improves this performance. Here, we report that appropriate Cu-doped Zn0.5 Cd0.5 S nanocrystals reach 21.4 mmol/h/g of H2 evolution rate without cocatalyst in the visible-light region, which is also 2.8 times as high as that of the undoped counterpart, and the corresponding apparent quantum efficiency is 18.8% at 428 nm. It is firstly confirmed that the Cu 2+ changes into Cu + after being doped by soft X-ray absorption spectroscopy (sXAS). We theoretically propose that the transformation of 2Cu 2+ to 2Cu + results in one adjacent S 2 − vacancy (VS ) in host during the doping process, while the Cu + -dopant and VS attract the photoexcited holes and electrons, respectively. Accordingly, the photocatalytic activity is improved due to the enhanced separation of photoexcited carriers accompanied with the enhanced light absorption resulting from the Cu + -dopant and 2Cu + /VS complex as possible active site for photocatalytic H2 evolution. Graphical abstract: Highlights: It was firstly found that the Cu 2+ doping source turned into Cu + after being doped into mesoporous Zn0.5 Cd0.5 S aggregated by nanocrystals. It was theoretically proposed that the Cu + dopant resulted in the spontaneous formation of S vacancies (VS ) in Zn0.5 Cd0.5 S. The Cu + dopant and VS would construct trap level and attract photoexcited holes and electrons, respectively. Appropriate Cu-doped Zn0.5 Cd0.5 S nanocrystals reach the highest 21.4 mmol/h/g of H2 evolution rate without cocatalyst in the visible-light region, which is also 2.8 times as high as that of the undoped counterpart.