Artificial Leaf Turns Sunlight into Electric Power

Scientists at the Massachusetts Institute of Technology have turned to Mother Nature for inspiration, inventing a device that mimics¹ photosynthesis², the process plants use to convert sunlight and water into usable energy.
MIT chemistry professor Daniel Nocera leaded research on the artificial leaf  project, says he and his colleagues took their cues from plants, which are literally³ buzzing with electricity.
"What happens is that sunlight comes in and hits the leaf and then the leaf immediately takes that sunlight and makes a wireless⁴ current," says Nocera.
During photosynthesis, the energy in sunlight splits water molecules⁵ into hydrogen and oxygen. The hydrogen joins with carbon dioxide to make sugar, an essential fuel for plant growth. In Nocera's laboratory, scientists replicated⁶ that chemical process using a silicon⁷ device about the size and shape of a playing card, only thinner. It's coated with nickel and cobalt catalysts⁸ that when exposed to water and ultraviolet light, accelerate a chemical reaction.
The hydrogen is then recombined with the oxygen in a fuel cell to produce electricity. Nocera's work builds on previous research. John Turner of the National Renewable Energy Laboratory pioneered the concept in 1998 using materials too expensive and unstable⁹ for commercialization.
Nocera says his so-called practical artificial leaf uses less expensive materials, is more stable and more efficient than that earlier design. He says the challenge is to collect the gases coming off the silicon and store them until the energy is needed. "It has to be engineered still," he adds. "It will be something that we will start doing soon. You'll be storing a fair amount of energy because this system is working at more or less the efficiency of the solar cell."
In laboratory experiments, Nocera's solar cell prototype operated continuously for 45 hours without a drop in electrical output. Nocera notes that it works in any type of water. "You can use natural water sources, which for us is a big deal, because if you are in rural parts of the world, especially where they are poor, it is really costly¹⁰ to bring in pure water and so, the fact that you can go ‘over there' to a puddle¹¹ and pick the water up and begin using it, is something that is very powerful for us."
Nocera believes the artificial leaf could be especially useful as an inexpensive source of electricity for low-income populations in developing countries. The goal, Nocera says, is to make each home its own power station. He predicts a commercial version of the artificial leaf will be on the market within three years.

1 mimics   

n.模仿名人言行的娱乐演员，滑稽剧演员( mimic的名词复数 )；善于模仿的人或物v.（尤指为了逗乐而）模仿( mimic的第三人称单数 )；酷似

参考例句：

• Methods:Models were generate by CT scan,Mimics software and Abaqus software. 方法：采用CT扫描，Mimics软件和Abaqus软件的CAD进行三维有限元模型的创建。 来自互联网
• Relaxing the mind and body mimics the effect that some blood-pressure pills would have. 放松身心会产生某些降压药才能产生的效果。 来自辞典例句

2 photosynthesis   

n.光合作用

参考例句：

• In apple trees photosynthesis occurs almost exclusively in the leaves.苹果树的光合作用几乎只发生在叶内。
• Chloroplasts are the structures in which photosynthesis happens.叶绿体就是光合作用发生的地方。

3 literally   

adv.照字面意义，逐字地；确实

参考例句：

• He translated the passage literally.他逐字逐句地翻译这段文字。
• Sometimes she would not sit down till she was literally faint.有时候，她不走到真正要昏厥了，决不肯坐下来。

4 wireless   

adj.无线的；n.无线电

参考例句：

• There are a lot of wireless links in a radio.收音机里有许多无线电线路。
• Wireless messages tell us that the ship was sinking.无线电报告知我们那艘船正在下沉。

5 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。

6 replicated   

复制( replicate的过去式和过去分词 )； 重复； 再造； 再生

参考例句：

• Later outplant the seedlings in a replicated permanent test plantation. 以后苗木出圃栽植成重复的永久性试验林。
• The phage has replicated and the donor cells have lysed. 噬菌体已复制和给体细胞已发生裂解。

7 silicon   

n.硅(旧名矽)

参考例句：

• This company pioneered the use of silicon chip.这家公司开创了使用硅片的方法。
• A chip is a piece of silicon about the size of a postage stamp.芯片就是一枚邮票大小的硅片。

8 catalysts   

n.催化剂( catalyst的名词复数 )；触媒；促进因素；有感染力的人

参考例句：

• The first catalytic converters were called conventional oxidation catalysts. 最初的转化器叫做常规氧化催化器。 来自辞典例句
• Many processes that are essential to the chemical industry use heterogeneous catalysts. 很多重要的化学工业过程就是使用多相催化剂的。 来自辞典例句

9 unstable   

adj.不稳定的，易变的

参考例句：

• This bookcase is too unstable to hold so many books.这书橱很不结实，装不了这么多书。
• The patient's condition was unstable.那患者的病情不稳定。

10 costly   

adj.昂贵的，价值高的，豪华的

参考例句：

• It must be very costly to keep up a house like this.维修这么一幢房子一定很昂贵。
• This dictionary is very useful,only it is a bit costly.这本词典很有用，左不过贵了些。

11 puddle   

n.(雨)水坑，泥潭

参考例句：

• The boy hopped the mud puddle and ran down the walk.这个男孩跳过泥坑，沿着人行道跑了。
• She tripped over and landed in a puddle.她绊了一下，跌在水坑里。