Construction and characterization of visible light active Pd nano-crystallite decorated and C-N-S-co-doped TiO₂ nanosheet array photoelectrode for enhanced photocatalytic degradation of acetylsalicylic acid

A photo-assisted deposition technique was adopted to construct highly dispersed Pd nano-crystallites on C-N-S-co-doped TiO₂ nanosheets (Pd/C-N-S-TiO₂ NS) arrays photoelectrodes prepared by one-step hydrothermal synthesis. The morphology, elemental composition, crystal structure, light absorption capability and photoelectrochemical (PECH) property of as-obtained Pd/C-N-S-TiO₂ NS electrodes were determined and investigated through the various characterizations. The photocatalytic (PC) and photoelectrocatalytic (PEC) activity of the Pd/C-N-S-TiO₂ NS electrode was evaluated through the degradation of acetylsalicylic acid and the formation of OH radicals. Compared with pristine TiO₂ NS, Pd/TiO₂ NS and C-N-S-TiO₂ NS, Pd/C-N-S-TiO₂ NS electrode displayed greatly enhanced PC and PEC activity towards the degradation of acetylsalicylic acid under visible light (λ > 420 nm) or Xenon light irradiation. The synergy effect of interfacial transfer of photoinduced electrons between Pd nanoparticles and TiO₂ NS as well as the external potential and intense visible light absorption induced by C, N and S co-doing promoted the effective charge separation and transfer and more visible photons to participate in the catalytic process on obtained Pd/C-N-S-TiO₂ NS, which were evidenced by a series of characterizations, resulting in highly efficient and stable PC and PEC activity. Moreover, the probable visible light PEC mechanism was proposed.