Protecting Artificial Leaves

Protecting Artificial Leaves

Author: Lisa-Marie Rauschendorfer

The artificial production of hydrogen from sunlight and water by semiconducting absorbers is a promising approach to generate environmentally friendly energy. State-of-the-art semiconductors have a high photovoltage and photon-to-charge-carrier conversion efficiency, but still lack of durability due to their tendency to degradation and passivation in acidic electrolytes.

Anahita Azarpira, Helmholtz-Zentrum for Materials and Energy GmbH, Berlin, Germany, and colleagues addressed this problem by the addition of an ultrathin organic protection layer in a two-step fabrication scheme. Firstly, hydrogen-terminated n-type silicon electrodes were exposed to an ethanol/iodine electrolyte. Under cathodic conditions the ethanol is activated by the iodine and subsequently reacts with the H-terminated silicon surface. In a second step, partly hydrated RuO2 powder catalyses the polymerization of ethanol resulting in a protection layer formed by polymerized ethyl-groups. RuO2 then proceeds to its original task in silicon electrodes: to catalyze the splitting of water to hydrogen and oxygen.

The resulting mulit-layer photoanode shows high stability and surpasses existing benchmarks of the photovoltage.


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