Department of Physics and Stephenson Institute for Renewable Energy, The University of Liverpool , Chadwick Building, Peach Street, Liverpool, L69 7ZF, U.K.
ACS Appl Mater Interfaces. 2016 Nov 2;8(43):29434-29441. doi: 10.1021/acsami.6b09364. Epub 2016 Oct 19.
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 NaSO as hole scavenger, triethanolamine (TEOA) replaces the original cysteine ligands in situ and prolongs the highly efficient and steady H evolution period by more than a factor of 10. It is shown that NaSO is consumed during H generation while TEOA makes no significant contribution to the H generation. An apparent quantum yield of 31.5%, a turnover frequency of 0.11 H/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.
胶体稳定性和半导体纳米晶体中的有效界面电荷转移对于水相光催化应用非常重要，因为它们分别提供长期的功能和高的光催化活性。然而，胶体稳定性和界面电荷转移效率很难同时优化，因为配体层通常既作为胶体悬浮液中纳米晶体的稳定壳层，又作为降低界面电荷转移效率的障碍。在这里，我们表明，对于半胱氨酸包覆的、Pt 修饰的 CdS 纳米晶体和 NaSO 作为空穴捕获剂，三乙醇胺（TEOA）原位取代原始的半胱氨酸配体，并将高效且稳定的 H 演化期延长了 10 倍以上。结果表明，在 H 生成过程中消耗了 NaSO，而 TEOA 对 H 生成没有明显贡献。在 TEOA 稳定的体系中，实现了 31.5%的表观量子效率、0.11 H/Pt/s 的周转率和快于 0.3 ps 的界面电荷转移速率。TEOA 与 CdS 的短长度、支化结构和弱结合以及溶液中足够的游离 TEOA 是同时增强胶体稳定性和保持有效界面电荷转移的关键。此外，TEOA 可商购且廉价，我们预计这种方法可以广泛应用于涉及胶体纳米晶体的许多光催化应用中。
