Photoelectrochemical degradation of anti-inflammatory pharmaceuticals at Bi2MoO6–boron-doped diamond hybrid electrode under visible light irradiation

Bi2MoO6 particles were selectively deposited onto a boron-doped diamond (BDD) surface from amorphous complex solution via a dip-coating method followed by calcination. Its structure was confirmed via Raman and X-ray diffraction analysis. Scanning electron microscopy showed that the resulting Bi2MoO6 particles scattered on the BDD substrate. The photoelectrochemical measurement of the Bi2MoO6–BDD electrode showed a clear improvement in the photocurrent under visible light irradiation, indicating a new hybrid system. Furthermore, the hybrid electrode was applied in the degradation of ibuprofen and naproxen, two kinds of non-steroidal anti-inflammatory drugs via photocatalysis, electro-oxidation, and photoelectrocatalytic processes. It is shown that ibuprofen can be degraded via photocatalysis and electro-oxidation process with the applied bias potential of 2.0 V. By contrast, ibuprofen and naproxen can be rapidly degraded via combined electro-oxidation and photocatalysis process under visible light irradiation. Furthermore, the degradation rate in the combined process is larger than the sum of photocatalysis and electro-oxidation processes. The ibuprofen and naproxen were also efficiently mineralized in the combined process. Finally, the main intermediates of ibuprofen degradation were also identified.