Enhanced Diclofenac Removal from Constructed Wetland Effluent Using a Photoelectrocatalytic System with N-TiO2 Nanocrystal-Modified TiO2 Nanotube Anode and Graphene Oxide/Activated Carbon Photocathode

This investigation reports on the efficacy of a photoelectrocatalysis (PEC) system enhanced by a nitrogen-doped TiO2 nanocrystal-modified TiO2 nanotube array (N-TiO2 NCs/TNTAs) anode paired with a graphene oxide/activated carbon (GO/AC) photocathode for diclofenac removal from effluent. The FE-SEM and EDX analyses validated the elemental composition of the anode—27.56% C, 30.81% N, 6.03% O, and 26.49% Ti. The XRD results confirmed the anatase phase and nitrogen integration, essential for photocatalytic activity enhancement. Quantum chemical simulations provided a comprehensive understanding of the red-shifted absorption bands in N-TiO2, and UV-vis DRS demonstrated a red-shift in absorption to the visible spectrum, indicating improved light utilization. The PEC configuration achieved a photocurrent density of 9.8 mA/dm2, significantly higher than the unmodified and solely nitrogen-doped counterparts at 4.8 mA/dm2 and 6.1 mA/dm2, respectively. Notably, this system reduced diclofenac concentrations by 58% within 75 min, outperforming standard photocatalytic setups. These findings underscore the potential of N-TiO2 NCs/TNTAs-AC-GO/PTFE composite material for advanced environmental photoelectrocatalytic applications.