Photoelectrochemical and Photocatalytic Studies by Applying an Organic P-N Bilayer for the Selective Oxidation of Ammonia to Dinitrogen

Ammonia (NH3) is a pollutant that needs to be treated properly. Its oxidative degradation to dinitrogen (N2) involves the transfer of six electrons, and thus, an active catalyst must be applied to accomplish the selective formation of N2 from NH3. In this work, polycrystalline Pt was newly prepared on a multi-walled carbon nanotube (MWCNT) supporter, which was used as a co-catalyst by embedding it in a Nafion® membrane (i.e., Nf[Pt/MWCNT]). The 10 nm-sized cubic Pt (100), considered as the active species for the corresponding oxidation, was well characterized by means of transmission electron microscopy and electrochemistry. We found that an organic p-n bilayer, comprising fullerene (n-type) and phthalocyanine (p-type), works as a photoanode capable of oxidation at the phthalocyanine surface. When applying Nf[Pt/MWCNT] as the co-catalyst at the organo-bilayer, the selective NH3 oxidation was confirmed to occur stably in terms of photoelectrochemistry and photocatalysis, particularly under visible light irradiation.