Simultaneous Optimization of Colloidal Stability and Interfacial Charge Transfer Efficiency in Photocatalytic Pt/CdS Nanocrystals

作者：Li, Wei^*; Lee, Jonathan R.; Jackel, Frank

来源：ACS Applied Materials & Interfaces, 2016, 8(43): 29434-29441.

DOI：10.1021/acsami.6b09364

• aggregation-free
• electron transfer
• hole scavenging
• transient absorption spectroscopy
• photocatalysis
• water splitting
• solar fuels

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 photo catalytic 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 H-2 evolution period by more than a factor of 10. It is shown that Na2SO3 is consumed during H-2 generation while TEOA makes no significant contribution to the H-2 generation. An apparent quantum yield of 31.5%, a turnover frequency of 0.11 H-2/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.

• 出版日期2016-11-2