Jul 4, 2012
Nanowire coating benefits solar energy conversion
Scientists have been busy exploring the use of silicon as active electrodes for the photoelectrolysis of seawater and generation of hydrogen (H2) fuel. However, technical hurdles remain. Problems with p-type silicon photocathodes include low interface kinetics for H2 evolution, which allows e–/h+ recombination to compete with the water reduction reaction, and chemical corrosion. Now, reporting their results in the journal Nanotechnology, researchers in the US have come up with a design to tackle both of these issues.
The team uses a nanostructured n-type ZnO coating on p-type silicon to enhance light absorption and charge separation/transfer, thus improving the surface kinetics for H2 evolution. Also, the metal nano-coating further catalyses the redox reaction and prevents corrosion.
Ongoing research involves exploiting other metal oxide nanowire coatings with smaller band gaps or improved chemical/electrochemical robustness on planar silicon, black silicon and/or silicon nanowire arrays (such as 3D nanowire heterostructures or “nanotrees”) to further increase energy conversion efficiency and make solar hydrogen production more practical.
Additional information can be found in the journal Nanotechnology.
About the author
Ke Sun is a PhD candidate in the Department of Electrical and Computer Engineering at the University of California, San Diego, US. His research interests include the synthesis and fabrication of nanomaterials for high-efficiency clean-energy collection and generation (solar cells and photoelectrochemical cells) and high-sensitivity sensors. Prof. Deli Wang is group leader, and works on nanomaterials, devices and systems for electronics, optoelectronics, clean energy, biosensing, and bio-nano- and human-machine interfaces.