Harnessing Infrared Photons for Photoelectrochemical Hydrogen Generation. A PbS Quantum Dot Based “Quasi-Artificial Leaf”

Abstract

Hydrogen generation by using quantum dot based heterostructures has emerged as a promising strategy to develop artificial photosynthesis devices. In the present study, we sensitize mesoporous TiO 2 electrodes with in-situ deposited PbS/CdS quantum dots (QDs), aiming at harvesting light in both the visible and the near infrared for hydrogen generation. This heterostructure exhibits a remarkable photocurrent of 6 mA·cm -2 leading to 60 ml·cm -2 ·day -1 hydrogen generation. Most importantly, confirmation of the contribution of infrared photons to H 2 generation was provided by the incident-photon-to-current-efficiency (IPCE), and the integrated current was in excellent agreement with that obtained through cyclic voltammetry.The main electronic processes (accumulation, transport and recombination) were identified by impedance spectroscopy, which appears as a simple and reliable methodology to evaluate the limiting factors of these photoelectrodes. Based on this TiO 2 /PbS/CdS heterostructrure, a "quasiartificial leaf" has been developed, which has proven to produce hydrogen under simulated solar illumination at (4.30 ± 0.25) ml·cm -2 ·day -1 .

One-step electrodeposition of CdSe on nanoparticulate titania films and their use as sensitized photoanodes for photoelectrochemical hydrogen production

“…Typical sensitizers of nanocrystalline titania (nc-TiO 2 ) is CdS, CdSe, PbS, etc. [1][2][3][4][5]. Almost all of them are usually synthesized on nc-TiO 2 films by Chemical-Bath-based procedures, which are very successful but time-consuming.…”

Recent progress in enhancing solar-to-hydrogen efficiency

“…The visible light response decreases while the electron injection driving force increases as the decrease of the particle size [64,65]. PbS/CdS co-sensitized mesoporous TiO 2 further extends the absorption spectral range to infrared photons [66]. TiO 2 /PbS/ CdS heterostructures exhibit a photocurrent density of 6 mA cm À2 .…”

Research Update: Strategies for efficient photoelectrochemical water splitting using metal oxide photoanodes

“…Recently, Trevisan et al demonstrated in situ growth of CdS and PbS QDs on mesoporous TiO 2 aiming at harvesting light in both visible and NIR regions and their application for PEC hydrogen generation. 101 In addition to in situ approaches, post-synthesis assembly approaches for QD sensitization have been also investigated. In particular, the simultaneous use of QDs with different, well-controlled sizes can be realized by the post-synthesis assembly.…”