Abstract:Ag and graphene co-sensitized TiO composites were successfully fabricated and used as photoanodes for photogenerated cathodic protection of 304 stainless steel (304SS) under visible light. Graphene films was firstly deposited onto the TiO nanotube (NT) films via cyclic voltammetric electrodeposition. Ag/graphene/TiO films were then fabricated via dipping and photoreduction method. The morphology, composition and optical response of the Ag/graphene/TiO NT composites were characterized by scanning electron micro… Show more
“…Such levels are associated with the formation of surface states at the interface of BiVO 4 /TiO 2 with a high BiVO 4 content. In addition, when the illumination is interrupted, the OCP for BiVO 4 and BiVO 4 /TiO 2 nanocomposites recovers more slowly than TiO 2 indicating that electrons are sluggishly transferred to species in the solution 66 . Figure 11 Time evolution of the open circuit potential (OCP) in the dark (off) and under UV illumination (on) for the synthetized nanocomposites.…”
Nanocomposites with different ratios of titanium dioxide and bismuth vanadate [TiO 2 ]/[BiVO 4 ] give rise to compatible electronic band structure alignment at their interfaces to ensure enhanced photoactivated charge transfer under visible light. The sol-gel method and suitable post-synthesis thermal treatments were used to synthesize different compositions with stabilized anatase phase of tio 2 and monoclinic scheelite polymorph BiVo 4. Structural, electronic and optical characterizations were performed and the results were analysed as a function of the stoichiometry, in which both crystalline structures show a clear junction formation among their characteristic stacking planes. Photocatalytic and (photo) electrochemical responses of the nanocomposites were investigated and tested for the degradation of azo dyes (Acid Blue-113, AB-113) (~ 99%) under visible light radiation. The nanocomposite with a mass ratio of (1:10) shows the highest photocatalytic efficiency compared to the other compositions. HRTEM images showed marked regions in which both crystalline structures form a clear junction and their characteristic planes. However, the increase of BiVO 4 content in the network overcomes the photocatalytic activity due to the decrease in the reduction potential of the photo-generated electrons with high recombination rates. Due to rapid increase in population and the world's rapid industrialization, natural water bodies are being heavily contaminated with industrial wastes 1,2,3. Pollutants present in the industrial effluents are classified as toxins, carcinogens, mutagens, teratogens, and endocrine-disrupting agents 4. Particularly, the presence of dyes in industrial effluents leads to a decreased penetration of sunlight and a reduction of the photosynthetic activities in aquatic ecosystems, as well as an increase in the biochemical oxygen demand 5. The dyes are specified as dispersive dyes (polyester, nylon and acetate) 6 , reactive dyes (Safira dye, HEXL) 7 , sulphur dyes, and vat dyes (viscous) 8. The Azo dyes are colorants that fall under all of the above-mentioned categories. They contain one or more-N=N-groups in their chemical structure, which consists of highly substituted aromatic rings 9. To ensure water purification, several known methods are well-established: desalination, distillation, filtration, flocculation, reverse osmosis, and sedimentation 10,11 , etc. However, the chemical structure of azo dyes leads to recalcitrant characteristics, i.e., they degrade slowly under natural conditions, and they are also resistant to conventional wastewater treatment processes 6. For this reason, Advanced Oxidation Processes (AOPs), have received a widespread attention in recent years, since they are a very convenient water treatment method that eliminates these types of contaminants 5,7. Among AOPs, photocatalysis is considered as a green alternative to attain an efficient purification of polluted water 12,13. Furthermore, the implementation of photoactive nanomaterials in water treatment show outstanding resul...
“…Such levels are associated with the formation of surface states at the interface of BiVO 4 /TiO 2 with a high BiVO 4 content. In addition, when the illumination is interrupted, the OCP for BiVO 4 and BiVO 4 /TiO 2 nanocomposites recovers more slowly than TiO 2 indicating that electrons are sluggishly transferred to species in the solution 66 . Figure 11 Time evolution of the open circuit potential (OCP) in the dark (off) and under UV illumination (on) for the synthetized nanocomposites.…”
Nanocomposites with different ratios of titanium dioxide and bismuth vanadate [TiO 2 ]/[BiVO 4 ] give rise to compatible electronic band structure alignment at their interfaces to ensure enhanced photoactivated charge transfer under visible light. The sol-gel method and suitable post-synthesis thermal treatments were used to synthesize different compositions with stabilized anatase phase of tio 2 and monoclinic scheelite polymorph BiVo 4. Structural, electronic and optical characterizations were performed and the results were analysed as a function of the stoichiometry, in which both crystalline structures show a clear junction formation among their characteristic stacking planes. Photocatalytic and (photo) electrochemical responses of the nanocomposites were investigated and tested for the degradation of azo dyes (Acid Blue-113, AB-113) (~ 99%) under visible light radiation. The nanocomposite with a mass ratio of (1:10) shows the highest photocatalytic efficiency compared to the other compositions. HRTEM images showed marked regions in which both crystalline structures form a clear junction and their characteristic planes. However, the increase of BiVO 4 content in the network overcomes the photocatalytic activity due to the decrease in the reduction potential of the photo-generated electrons with high recombination rates. Due to rapid increase in population and the world's rapid industrialization, natural water bodies are being heavily contaminated with industrial wastes 1,2,3. Pollutants present in the industrial effluents are classified as toxins, carcinogens, mutagens, teratogens, and endocrine-disrupting agents 4. Particularly, the presence of dyes in industrial effluents leads to a decreased penetration of sunlight and a reduction of the photosynthetic activities in aquatic ecosystems, as well as an increase in the biochemical oxygen demand 5. The dyes are specified as dispersive dyes (polyester, nylon and acetate) 6 , reactive dyes (Safira dye, HEXL) 7 , sulphur dyes, and vat dyes (viscous) 8. The Azo dyes are colorants that fall under all of the above-mentioned categories. They contain one or more-N=N-groups in their chemical structure, which consists of highly substituted aromatic rings 9. To ensure water purification, several known methods are well-established: desalination, distillation, filtration, flocculation, reverse osmosis, and sedimentation 10,11 , etc. However, the chemical structure of azo dyes leads to recalcitrant characteristics, i.e., they degrade slowly under natural conditions, and they are also resistant to conventional wastewater treatment processes 6. For this reason, Advanced Oxidation Processes (AOPs), have received a widespread attention in recent years, since they are a very convenient water treatment method that eliminates these types of contaminants 5,7. Among AOPs, photocatalysis is considered as a green alternative to attain an efficient purification of polluted water 12,13. Furthermore, the implementation of photoactive nanomaterials in water treatment show outstanding resul...
“…[93] Numerous reports of energy-storing TiO 2 /WO 3 heterojunction for anti-corrosion have been reported, [95][96][97][98][99][100][101] as well as equivalent structures with bronze formation reaction based on MoO 3 , [102] SnO 2 , [103][104][105][106] and V 2 O 5 . [107] Further approaches on the electron pools involved Mn─Ti, [108] In─Ti, [109][110][111] Ni─Ti, [112,113] Bi─Ti, [114][115][116] Ce─Ti, [117] Mn─Ti, [108] Ag─Ti, [118] SrTiO 3 ─TiO 2 . [119] One of the best-performing photoanode for cathodic protection consisted of a Fe-doped TiO 2 array of nanotubes, reported by Li et al [120] The doping extended the absorption from the UV to the full visible region and led to outstanding stored charge longevity.…”
Section: Photocathodic Protection For Anti-corrosionmentioning
Photochargeable semiconductors enable energy harvesting and storage in a single material. Charges separated upon absorption of photons can accumulate in highly energetic trap states if morphology, size, and chemical composition are appropriately chosen. For example, electrons can survive for several hours if hole scavengers are used to prevent their recombination with photogenerated holes, and their negative charge is balanced by positive counter‐ions. The first database of charge‐storing semiconductors is recently released, containing information from more than 50 publications within the past 40 years. Now, the database has been updated with more than 90 entries from the latest works on the topic. These materials have been largely utilized in the context of “dark photocatalysis”, that is, redox reactions enabled by photocharged semiconductors long after cessation of light irradiation. Nevertheless, a variety of further potential applications have not received enough visibility, including memory storage, steel anti‐corrosion, sensors, and micromotors. In this review, the key figures of merit of photocharged semiconductors and the empirical relationships found between them is highlighted. After showing the latest advances in dark photocatalysis, it is discussed how other application fields may benefit from these materials. For each area, promising research directions based on the findings from the database are recommended.
“…The protection performance is investigated by comparing the surface potential changes of 304SS under simulated solar light irradiation. [60] As displayed in Figure 5b, the OCP (open-circuit potential) values of 304SS in 3.5 wt% NaCl solution were investigated. Before being coupled with photoanodes, the 304SS corrosion potential is approximately -0.16 V vs. Ag/AgCl.…”
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