Production of hydrogen gas directly from solar energy
Researchers from the Federal Materials Testing and Research Laboratory (Empa) have developed a photoeletrochemical cell (PEC) [1]. Based on an imitation of the moth eye, which captures a maximum of light while reflecting as little as possible, the photoanode of the PEC cell consists of spherules made of inexpensive materials (iron oxide and tungsten oxide). This combination achieves the energy necessary to split water into dihydrogen and oxygen.
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[1] As a reminder: photoelectrochemical cells (PEC) allow the splitting of the water molecule into dihydrogen and dioxygen directly from solar radiation without passing through the transport of electric current. The operating principle of the PEC cell is as follows. The photoanode is in contact with an aqueous solution (water + electrolyte). The photons of solar radiation arriving on the photoanode provide the energy necessary for the ejection of electrons and thus for the formation of holes. These holes will allow the oxidation of water to produce oxygen molecules (oxygen gas, O2). There is therefore a splitting of water molecules into O2 and into hydrogen ions H +. While the electrons produced at the photoanode are transported to the cathode via the electrical connection, the hydrogen ions are transported to the cathode within the aqueous solution to react with the electrons in a reduction reaction and thus form dihydrogen (H2 gas ).
Source: http://www.bulletins-electroniques.com/ ... /78073.htm
