Photocatalytic water splitting with a quantum efficiency of almost unity
Photocatalytic water splitting with a quantum efficiency of almost unity
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DOI：
10.1038/s41586-020-2278-9
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发表时间：
2020-05-28
期刊：
影响因子：
64.8
通讯作者：
Domen, Kazunari
中科院分区：
文献类型：
--
作者：
Takata, Tsuyoshi;Jiang, Junzhe;Domen, Kazunari
使用颗粒光催化剂以2：1的化学计量比释放氢气和氧气的整体水分解是实现可扩展且经济可行的太阳能制氢的潜在手段。为了获得高的太阳能转换效率，必须在很宽的波长范围内提高光催化反应的量子效率，并且需要设计具有窄带隙的半导体。然而，使用现有光催化剂与整体水裂解相关的量子效率通常低于10%（1，2）。因此，颗粒光催化剂是否能够使极大吸能水裂解反应的量子效率达到100%仍然是一个悬而未决的问题。在这里，我们展示了在350和360纳米之间的波长处高达96%的外部量子效率下的整体水分解，这相当于使用改性的铝掺杂钛酸锶（SrTiO 3：Al）光催化剂（3，4）的内部量子效率几乎为1。通过选择性光沉积助催化剂Rh/Cr_2O_3（参考文献1），(5))和CoOOH（参考文献（3，6））分别对于使用各向异性电荷传输的半导体颗粒的不同晶面上的析氢和析氧反应，可以分别促进析氢和析氧反应。这使得多个连续的前向电荷转移而没有反向电荷转移，达到了整体水裂解的量子效率的上限。我们的工作证明了无电荷复合损失的整体水分解的可行性，并介绍了一种理想的助催化剂/光催化剂结构，用于有效的水分解。
Overall water splitting, evolving hydrogen and oxygen in a 2:1 stoichiometric ratio, using particulate photocatalysts is a potential means of achieving scalable and economically viable solar hydrogen production. To obtain high solar energy conversion efficiency, the quantum efficiency of the photocatalytic reaction must be increased over a wide range of wavelengths and semiconductors with narrow bandgaps need to be designed. However, the quantum efficiency associated with overall water splitting using existing photocatalysts is typically lower than ten per cent(1,2). Thus, whether a particulate photocatalyst can enable a quantum efficiency of 100 per cent for the greatly endergonic water-splitting reaction remains an open question. Here we demonstrate overall water splitting at an external quantum efficiency of up to 96 per cent at wavelengths between 350 and 360 nanometres, which is equivalent to an internal quantum efficiency of almost unity, using a modified aluminium-doped strontium titanate (SrTiO3:Al) photocatalyst(3,4). By selectively photodepositing the cocatalysts Rh/Cr2O3 (ref.(5)) and CoOOH (refs.(3,6)) for the hydrogen and oxygen evolution reactions, respectively, on different crystal facets of the semiconductor particles using anisotropic charge transport, the hydrogen and oxygen evolution reactions could be promoted separately. This enabled multiple consecutive forward charge transfers without backward charge transfer, reaching the upper limit of quantum efficiency for overall water splitting. Our work demonstrates the feasibility of overall water splitting free from charge recombination losses and introduces an ideal cocatalyst/photocatalyst structure for efficient water splitting.