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The role of carbon dots – derived underlayer in hematite photoanodes

DOI: 10.1039/D0NR06139E DOI Help

Authors: Qian Guo (Queen Mary University of London) , Hui Luo (Imperial College London) , Jifang Zhang (Tsinghua University) , Qiushi Ruan (University College London) , Arun Prakash Periasamy (Queen Mary University of London) , Yuanxing Fang (Fuzhou University) , Zailai Xie (Fuzhou University) , Xuanhua Li (Northwestern Polytechnical University) , Xinchen Wang (Fuzhou University) , Junwang Tang (University College London) , Joe Briscoe (Queen Mary University of London) , Magdalena Titirici (Imperial College London) , Ana Belen Jorge (Queen Mary University of London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nanoscale , VOL 29

State: Published (Approved)
Published: September 2020
Diamond Proposal Number(s): 22447

Open Access Open Access

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.

Subject Areas: Materials, Chemistry, Energy

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