Department of Electrical & Computer Engineering, University of Houston, Houston, Texas 77204, USA.
1] Department of Electrical & Computer Engineering, University of Houston, Houston, Texas 77204, USA [2] College of Electronics & Information Engineering, Sichuan University, Chengdu 610064, China.
Nat Nanotechnol. 2014 Jan;9(1):69-73. doi: 10.1038/nnano.2013.272. Epub 2013 Dec 15.
The generation of hydrogen from water using sunlight could potentially form the basis of a clean and renewable source of energy. Various water-splitting methods have been investigated previously, but the use of photocatalysts to split water into stoichiometric amounts of H2 and O2 (overall water splitting) without the use of external bias or sacrificial reagents is of particular interest because of its simplicity and potential low cost of operation. However, despite progress in the past decade, semiconductor water-splitting photocatalysts (such as (Ga1-xZnx)(N1-xOx)) do not exhibit good activity beyond 440 nm (refs 1,2,9) and water-splitting devices that can harvest visible light typically have a low solar-to-hydrogen efficiency of around 0.1%. Here we show that cobalt(II) oxide (CoO) nanoparticles can carry out overall water splitting with a solar-to-hydrogen efficiency of around 5%. The photocatalysts were synthesized from non-active CoO micropowders using two distinct methods (femtosecond laser ablation and mechanical ball milling), and the CoO nanoparticles that result can decompose pure water under visible-light irradiation without any co-catalysts or sacrificial reagents. Using electrochemical impedance spectroscopy, we show that the high photocatalytic activity of the nanoparticles arises from a significant shift in the position of the band edge of the material.
利用阳光从水中产生氢气有可能成为清洁可再生能源的基础。先前已经研究了各种水分解方法，但使用光催化剂将水分解为化学计量的 H2 和 O2（整体水分解）而无需外部偏置或牺牲试剂特别有趣，因为它简单且操作成本可能较低。然而，尽管在过去十年中取得了进展，但半导体水分解光催化剂（例如（Ga1-xZnx）（N1-xOx））在超过 440nm 的波长下并不表现出良好的活性（参考文献 1、2、9），并且可以收集可见光的水分解装置的太阳能到氢气的效率通常约为 0.1%。在这里，我们表明氧化钴（CoO）纳米粒子可以以约 5%的太阳能到氢气效率进行整体水分解。光催化剂是使用两种不同的方法（飞秒激光烧蚀和机械球磨）从非活性 CoO 微粉合成的，所得的 CoO 纳米粒子可以在可见光照射下分解纯水，而无需任何助催化剂或牺牲试剂。使用电化学阻抗谱，我们表明纳米粒子的高光催化活性源于材料能带边缘位置的显著移动。
