Simultaneous optimization of colloidal stability and interfacial charge transfer efficiency in photocatalytic Pt/CdS nanocrystals

Colloidal stability and efficient interfacial charge transfer in semiconductor nanocrystals are of great importance for photocatalytic applications in aqueous solution since they provide long-term functionality and high photocatalytic activity, respectively. However, colloidal stability and interfacial charge transfer efficiency are difficult to optimize simultaneously since the ligand layer often acts as both a shell stabilizing the nanocrystals in colloidal suspension and a barrier reducing the efficiency of interfacial charge transfer. Here, we show that, for cysteine-coated, Pt-decorated CdS nanocrystals and Na2SO3 as hole scavenger, triethanolamine (TEOA) replaces the original cysteine ligands in situ and prolongs the highly efficient and steady H2 evolution period by more than a factor of 10. It is shown that Na2SO3 is consumed during H2 generation while TEOA makes no significant contribution to the H2 generation. An apparent quantum yield of 31.5%, a turnover frequency of 0.11 H2/Pt/s, and an interfacial charge transfer rate faster than 0.3 ps were achieved in the TEOA stabilized system. The short length, branched structure and weak binding of TEOA to CdS as well as sufficient free TEOA in the solution are the keys to enhancing colloidal stability and maintaining efficient interfacial charge transfer at the same time. Additionally, TEOA is commercially available and cheap, and we anticipate that this approach can be widely applied in many photocatalytic applications involving colloidal nanocrystals.

Martin Forstner and Hannelore Lee-Jahnke: CIUTI-Forum Paris 2005: Regards sur les aspects culturels de la communication

Book review: CIUTI-Forum Paris 2005: Regards sur les aspects culturels de la communication. Martin Forstner and Hannelore Lee-Jahnke (eds). Bern: Peter Lang, 2006. xii + 307 pp. ISBN 978-3-03910-834-4.

Jonathan Gibson

Professor Jonathan Gibson MB BS MD FRCSEd, FRCOphth (1966-1971) is a Consultant Ophthalmic Surgeon for the Heart of England NHS Trust, Birmingham and a Professor of Ophthalmology at the University of Aston. He looks back at his time at Merchant Taylors’ and his career.