Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6454201 | Applied Catalysis B: Environmental | 2017 | 10 Pages |
â¢C, N codoped TiO2 nanotube arrays exhibited high visible-light photoreactivity.â¢Synergistic effect of PEC system was quantified in terms of photocurrent.â¢PEC exhibited effective separation of electrons and holes.â¢PFOA was readily degraded in PEC system over C-N-NTNA electrode.
We studied the synergistic effect of photoelectrochemical reactions exemplified by concurrent oxidization of perfluorooctanoic acid (PFOA) and hydrogen generation over carbon and nitrogen codoped TiO2 nanotube arrays (C-N-TNTAs) photoanode. The synthesized C-N-TNTAs were characterized by extended X-ray absorption fine structure (EXAFS) and X-ray diffraction (XRD) and results confirmed the successful doping of carbon and nitrogen into the TNTAs framework without altering its crystalline structure. Mott-Schottky analysis yielded a donor density of 3.547 Ã 1018/cm3 and 1.159 Ã 1018/cm3 for TNTA and C-N-TNTA, respectively. The photogenerated electrons had a lifetime (Ïel) of 2.52, 4.01, and 6.34 ms under biased potential of 0, 0.5, and 1.0 V (vs. Ag/AgCl), respectively, indicating the increase in lifetime of phtogenerated electrons in photoelectrochemical (PEC) process. The synergetic effect was further quantified in terms of current/time profile at bias potential of 0 V at 1.1 mA and 1 V at 3.1 mA, individually. Results showed an increase in synergetic efficiency of 56 and 65% at a biased potential of 0.5 and 1.0 V, respectively. PEC effectively separated the photogenerated electron-hole pairs and enhanced the oxidation and reduction capability of the system. PFOA removal reached 56.1% in 180 min (initial concentration = 40 mg/L) over the C-N-TNTA photoanode in PEC mode. Results showed that perfluorooctanate, C7F15COOâ, was first adsorbed on the C-N-TNTA anode surface followed by formation of C6F13COOâ after losing CF2 units. Results of electron spin resonance (ESR) further confirmed that reactive species such as OH and CH3 were responsible for the decomposition of PFOA during PEC reactions.
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