Nanocrystalline Water Splitting Photodiodes II: Device Engineering, Integration and Scale-up

摘要化石燃料是大多数工业化国家的主要能源，全球库存正迅速耗尽，促使人们对替代能源的兴趣与日俱增。近年来，随着越来越多的政治和社会接受的观察表明，燃烧化石燃料发电即使不是全球变暖的主要贡献者，也是全球变暖的主要原因，这种浓厚的兴趣大大加剧了这种兴趣，每年向大气中排放约8.0亿吨二氧化碳，约占目前大气水平的10%。在可能替代化石燃料的可再生能源中，只有阳光或太阳能有能力满足当前的全球能源需求。事实上，落在地球上的太阳能比人类目前的能源需求量高出5000倍。不幸的是，它的形式并不总是可以随时利用，而是需要转化为电力或作为化学燃料储存。使用光伏设备将太阳能转换为电能，如硅太阳能电池或使用染料敏化太阳能电池，已经得到了很好的证实。然而，电能不容易大量储存，而且太阳能是全天候和间歇性的，在我们最需要的时候，也就是冬天的晚上，电能最少。因此，确实需要一种高效(10%)、廉价(每平方米5 GB)的太阳能转换装置，以产生一种随时可利用的化学燃料。太阳能直接驱动的水分解系统的优点是，它将太阳能转化为一种化学形式，即氢气，可以很容易地储存或运输，能源成本最低，在需要时使用，用作燃料时没有污染，因为产品是水。在该项目的第一阶段，研究人员能够调查基本特性并开发小型实验室原型水分裂二极管。特别是，研究表明，半导体-金属载体界面的精心设计是获得高活性的关键，获得尽可能高的比表面积、孔隙率和光催化层的组成也是如此。需要进一步改进光触媒薄膜的附着力、可行的放大生产方法，以创造在现实生活条件下高效和有效运行的实用原型。该装置还需要与某种类型的燃料电池集成，才能广泛用作能源解决方案。因此，该提议项目(阶段2)终点的目标是制造高效、放大、提议的原始形式文件第3页日期打印：12/10/2010 10：48：54TS/I002855/1保存日期：12/10/2010 10：39：12商业演示能够收集太阳能，以(I)按或接近家庭规模将水分离成氢和氧工艺流，(Ii)具有最终的、廉价的优化设计，这在生命周期分析和综合材料选择方面是可持续的，以及(Iii)在将设备整合到国内使用模式方面获得重要和足够的技术诀窍；最值得注意的是通过商用燃料电池或燃烧器解决氢存储和随后使用的问题。第二阶段的终点将提供一个可行的装置，使用优化的催化剂(S)和光催化剂，并在以下方面采用最合适的涂层方法：(I)高活性、坚固性和可扩展性(Ii)经济影响；(Iii)环境、伦理和社会考虑。

Summary Fossil fuels are the primary source of energy for most industrialised countries and global stocks are being rapidly depleted, prompting a growing interest in alternative energy sources. In recent years this keen interest has sharpened considerably with the increasingly politically and socially accepted observation that burning fossil fuels to create electricity is a, if not the, major contributor to global warming, releasing into the atmosphere every year ca. 8.0 Gig tonnes of carbon dioxide, CO2, i.e. ca. 10% of present atmospheric levels. Of the renewable energy resources that might substitute for the fossil fuels, only sunlight, or solar energy, has the capability to satisfy current global energy demands. Indeed, the amount of solar energy falling on the Earth is exceeding humankind's present energy requirements by > 5000 times. Unfortunately it is not in a form that can be always readily utilised but, instead, needs to be converted into electricity or stored as a chemical fuel. The conversion of solar to electrical energy using photovoltaic devices, such as the silicon solar cell or using dye-sensitised solar cells, is well-established. However, electrical energy is not easily stored in large amounts and solar energy is diurnal and intermittent and there is least of it when we most need it, i.e. at night in winter. As a consequence, there is a real need for an efficient (> 10%), inexpensive (< £5 per m2) solar energy conversion device that generates a readily utilised chemical fuel. The advantage of a direct solar-driven, water-splitting system is that it converts the sun's energy into a chemical form, i.e. hydrogen, that can be readily stored or transported at minimal energy cost and used when needed and is non-polluting when used as a fuel, since the product is water. In stage 1 of this project, the researchers were able to investigate the fundamental properties and develop small laboratory prototype water splitting diodes. In particular, it was shown that careful engineering of the semiconductor-metal support interface was critical to high activity, as was the need to obtain a high as possible surface area, porosity and composition of the photocatalyst layer. Further improvements with regard to photocatalyst film adhesion, viable scale-up production methods are required to create practical prototypes which would run efficiently and effectively under real life conditions. This device will also require integration with a fuel cell of some kind in order to be of broad use as an energy solution. Therefore, the target at the end-point of this proposed project (Stage 2) is the fabrication of an efficient, scaled up, Proposal original proforma documentPage 3 of 10 Date printed: 12/10/2010 10:48:54TS/I002855/1 Date saved: 12/10/2010 10:39:12commercial demonstrator capable of harvesting solar energy to (i) split water into hydrogen and oxygen process streams on or near to domestic scale, (ii) have a final, inexpensive optimised design, which is sustainable in terms of life cycle analysis and comprehensive materials selection and (iii) gain significant and sufficient know how in terms of device integration into domestic utilisation model; most notably addressing the issues of hydrogen storage and subsequent usage via a commercial fuel cell or burner. The end point of Stage 2 will deliver a viable device, using optimised catalyst(s) and photocatalysts and the most suitable coating method in terms of (i) high activity and robustness and scalability (ii) economic impact; and (iii) environmental, ethical and societal considerations.