Issue 39, 2020

The role of carbon dots – derived underlayer in hematite photoanodes

Abstract

Hematite is a promising candidate as photoanode for solar-driven water splitting, with a theoretically predicted maximum solar-to-hydrogen conversion efficiency of ∼16%. However, the interfacial charge transfer and recombination greatly limits its activity for photoelectrochemical water splitting. Carbon dots exhibit great potential in photoelectrochemical water splitting for solar to hydrogen conversion as photosensitisers and co-catalysts. Here we developed a novel carbon underlayer from low-cost and environmental-friendly carbon dots through a facile hydrothermal process, introduced between the fluorine-doped tin oxide conducting substrate and hematite photoanodes. This led to a remarkable enhancement in the photocurrent density. Owing to the triple functional role of carbon dots underlayer in improving the interfacial properties of FTO/hematite and providing carbon source for the overlayer as well as the change in the iron oxidation state, the bulk and interfacial charge transfer dynamics of hematite are significantly enhanced, and consequently led to a remarkable enhancement in the photocurrent density. The results revealed a substantial improvement in the charge transfer rate, yielding a charge transfer efficiency of up to 80% at 1.25 V vs. RHE. In addition, a significant enhancement in the lifetime of photogenerated electrons and an increased carrier density were observed for the hematite photoanodes modified with a carbon underlayer, confirming that the use of sustainable carbon nanomaterials is an effective strategy to boost the photoelectrochemical performance of semiconductors for energy conversion.

Graphical abstract: The role of carbon dots – derived underlayer in hematite photoanodes

Supplementary files

Article information

Article type
Paper
Submitted
24 Aug. 2020
Accepted
23 Sept. 2020
First published
24 Sept. 2020
This article is Open Access
Creative Commons BY license

Nanoscale, 2020,12, 20220-20229

The role of carbon dots – derived underlayer in hematite photoanodes

Q. Guo, H. Luo, J. Zhang, Q. Ruan, A. Prakash Periasamy, Y. Fang, Z. Xie, X. Li, X. Wang, J. Tang, J. Briscoe, M. Titirici and A. B. Jorge, Nanoscale, 2020, 12, 20220 DOI: 10.1039/D0NR06139E

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