Photoelectrocatalytic degradation of p-chloronitrobenzene by g-C3N4/TiO2 nanotube arrays photoelectrodes under visible light irradiation.

As a typical refractory pollutant, p -chloronitrobenzene (p -CNB) from industrial wastewater poses a serious threat to the aquatic environment safety and human health. The photoelectrocatalytic (PEC) technology is regarded as a promising and cleaner approach for p -CNB removal. Therefore, the graphitic carbon nitride (g-C 3 N 4) modified TiO 2 nanotube arrays (g-C 3 N 4 /TNAs) were prepared as the photoelectrodes for p -CNB degradation. The PEC degradation efficiency for p -CNB by g-C 3 N 4 /TNAs (0.00484 min−1) was much higher than that by bare TNAs (0.00135 min−1) under visible light. The g-C 3 N 4 /TNAs photoelectrodes exhibited excellent visible-light response, efficient charges separation and high redox potentials of electron/hole, which was favorable for p -CNB degradation. The radical scavenging experiments indicated that both reductive electrons and oxidized species (holes and ·OH) played crucial roles simultaneously during the dechlorination process, whereas the mineralization of p -CNB mainly depended on the photo-generated holes and ·OH. The degradation pathways of p -CNB were proposed through GC/MS spectra. The acute toxicity, bioaccumulation factor and mutagenicity of identified intermediates were reduced after PEC degradation by g-C 3 N 4 /TNAs photoelectrodes. The Z-scheme g-C 3 N 4 /TNAs provided an efficient approach for simultaneous dechlorination and mineralization of refractory pollutants. Image 1 • Z-scheme g-C 3 N 4 /TNAs reduced recombination of photo-generated electron-hole pairs. • g-C 3 N 4 /TNAs exhibited high PEC degradation for p -CNB under visible light. • Reductive electrons played crucial roles during the dechlorination process. • The degradation pathways of p -CNB and its intermediates toxicity was analyzed. [ABSTRACT FROM AUTHOR]