Nanowire Forests Use Sunlight To Split Water

An anonymous reader sends this excerpt from IEEE Spectrum's Nanoclast blog: "One of the fundamental problems with fuel cells has been the cost of producing hydrogen. While hydrogen is, of course, the most abundant element, it attaches itself to other elements like nitrogen or fluorine, and perhaps most ubiquitously to oxygen to create the water molecule. ... Now researchers at University of California, San Diego have developed a quite different approach to mimicking photosynthesis for splitting water molecules by using a 3D branched nanowire array that looks like a forest of trees. ... The nanowire forest [uses] the process of photoelectrochemical water-splitting to produce hydrogen gas. The method used by the researchers, which was published in the journal Nanoscale (abstract), found that the forest structure of the nanowires, which has a massive amount of surface area, not only captured more light than flat planar designs, but also produced more hydrogen gas."

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Re:Hmmm... ZnO band gap is 3.37 eV

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Look at the carbon fixing (CO2-transforming) enzyme in nature: Rubisco. The elegance of the photon capturing and energy transport systems around it, and the machinery required to assemble the enzyme itself, will make you weep in amazement that it ever could have happened. The slow throughput of the system (molecules per second) and its bungling propensity to run backwards and re-oxidize (respiration), will make you weep in frustration.

Some plants (the C4 plants, such as maize/corn, sugar cane, and sorghum, typically evolved in hotter climates) cheat this up some by structural improvements that increase the concentration of CO2 through an intermediate structure.

We very likely have a lot of hard but interesting work to do, before we can design something comparable or better for human purposes.