State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory for Clean Energy, 457 Zhongshan Road, Dalian 116023, People's Republic of China.
Philos Trans A Math Phys Eng Sci. 2013 Jul 1;371(1996):20110430. doi: 10.1098/rsta.2011.0430. Print 2013 Aug 13.
A photocatalyst is defined as a functional composite material with three components: photo-harvester (e.g. semiconductor), reduction cocatalyst (e.g. for hydrogen evolution) and oxidation cocatalyst (e.g. for oxidation evolution from water). Loading cocatalysts on semiconductors is proved to be an effective approach to promote the charge separation and transfer, suppress the charge recombination and enhance the photocatalytic activity. Furthermore, the photocatalytic performance can be significantly improved by loading dual cocatalysts for reduction and oxidation, which could lower the activation energy barriers, respectively, for the two half reactions. A quantum efficiency (QE) as high as 93 per cent at 420 nm for H₂ production has been achieved for Pt-PdS/CdS, where Pt and PdS, respectively, act as reduction and oxidation cocatalysts and CdS as a photo-harvester. The dual cocatalysts work synergistically and enhance the photocatalytic reaction rate, which is determined by the slower one (either reduction or oxidation). This work demonstrates that the cocatalysts, especially the dual cocatalysts for reduction and oxidation, are crucial and even absolutely necessary for achieving high QEs in photocatalytic hydrogen production, as well as in photocatalytic water splitting.
光收集器（例如半导体）、还原助催化剂（例如用于析氢）和氧化助催化剂（例如用于水氧化）。将助催化剂负载到半导体上被证明是促进电荷分离和转移、抑制电荷复合以及提高光催化活性的有效方法。此外，通过负载还原和氧化的双助催化剂可以显著提高光催化性能，分别降低两个半反应的活化能垒。Pt-PdS/CdS 在 420nm 处实现了高达 93%的 H₂ 产率量子效率（QE），其中 Pt 和 PdS 分别作为还原和氧化助催化剂，CdS 作为光收集器。双助催化剂协同作用，提高了光催化反应速率，该速率由较慢的一个（还原或氧化）决定。这项工作表明，助催化剂，特别是还原和氧化的双助催化剂，对于实现光催化制氢和光解水的高 QE 至关重要，甚至是绝对必要的。
