Construction of NiO and Ti3+ self-doped TNTs thin film as a high quantum yield p-n type heterojunction via a novel photoelectrodeposition-assisted anodization method

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 2021-09, Vol.418, p.113433, Article 113433
• Main Authors: Pasikhani, Javad Vahabzadeh, Aliabadi, Bahareh Ghorbani, Gilani, Neda, Pirbazari, Azadeh Ebrahimian
• Format: Article
• Language: English
• Subjects: Anodic TNTs; NiO; p-n type heterojunction; Photo-induced charge generation; Photocatalytic degradation
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/j.jphotochem.2021.113433

[Display omitted] •NiO-TNTs were synthesized by the photoelectrodeposition-assisted anodization method.•Introduction of Ni2+ and Ti3+ significantly narrowed the band gap energy of TNTs.•Photocurrent density of NiO-TNTs was boosted due to the internal electric field.•The sample containing 4 wt% Ni (NiO-TNTs (4%)) had the best photocatalytic performance.•NiO-TNTs (4%) degraded 71% and 100% of 2,4-dichlorophenol under visible and UV light. Recently, p-n type heterojunctions have been considered promising photocatalysts for application in energy conversion and storage systems. Therefore, in this study, the photoelectrodeposition-assisted anodization method has been proposed as a novel procedure to construct a p-n type heterojunction hybrid consisting of NiO nanoparticles (with different dosages) and 1D TiO2 nanotube arrays (NiO/TNTs) for wastewater purification. The results revealed that using the photoelectrodeposition-assisted anodization method not only led to the introduction of Ni2+ and Ti 3+ into TiO2 anatase lattice, but also significantly enlarged TNTs’ dimension. Furthermore, incorporating TNTs with NiO had a significant impact on its optical properties, in which doping 4 wt% of Ni2+ (NiO-TNTs (4%)) reduced the band gap energy from 3 to 1.6 eV. Also, by coupling an optimum dosage of NiO, the photocurrent density and photoconversion efficiency of TNTs were remarkably boosted from 0.17 to 0.58 mA.cm−2 and from 0.11% to 0.34%, respectively. Due to the promotion in optical properties and photo-induced charge generation, NiO-TNTs (4%) indicated much better photocatalytic activity than the pure sample. As compared with TNTs, the 2,4-dichlorophenol degradation percentage by NiO-TNTs (4%) increased from 75% to 100% under UV and from 49% to 71% under visible light irradiation. Moreover, the kinetics study confirmed that all photocatalytic reactions followed zero-order kinetics. Based on scavenging reactive species tests, holes (h+) had the main portion (with 43%) in 2,4-dichlorophenol degradation by NiO-TNTs (4%). The rest of the degradation pathways were proceeded with e-, •OH, and •O2– species by accounting for 27%, 21% and 9%, respectively.