Semiconductor quantum dot-sensitized rainbow photocathode for effective photoelectrochemical hydrogen generation.
Hongjin LvCongcong WangGuocan LiRebeckah BurkeTodd D KraussYongli GaoRichard EisenbergPublished in: Proceedings of the National Academy of Sciences of the United States of America (2017)
The present study reports the fabrication of CdSe quantum dot (QD)-sensitized photocathodes on NiO-coated indium tin oxide (ITO) electrodes and their H2-generating ability upon light irradiation. A well-established spin-coating method was used to deposit CdSe QD stock solution onto the surface of NiO/ITO electrodes, thereby leading to the construction of various CdSe QD-sensitized photocathodes. The present report includes the construction of rainbow photocathodes by spin-coating different-sized QDs in a sequentially layered manner, thereby creating an energetically favorable gradient for charge separation. The resulting rainbow photocathodes with forward energetic gradient for charge separation and subsequent electron transfer to a solution-based hydrogen-evolving catalyst (HEC) exhibit good light-harvesting ability and enhanced photoresponses compared with the reverse rainbow photocathodes under white LED light illumination. Under minimally optimized conditions, a photocurrent density of as high as 115 μA⋅cm-2 and a Faradaic efficiency of 99.5% are achieved, which is among the most effective QD-based photocathode water-splitting systems.
Keyphrases
- quantum dots
- room temperature
- reduced graphene oxide
- electron transfer
- visible light
- solid state
- sensitive detection
- energy transfer
- density functional theory
- liquid chromatography
- ionic liquid
- highly efficient
- single molecule
- transition metal
- carbon nanotubes
- gold nanoparticles
- emergency department
- electronic health record
- molecular dynamics