Photoelectrocatalytic Degradation Efficiency Research Articles

Unraveling Electron-deficient Setaria-viridis-like Co3O4@MnO2 heterostructure with superior photoelectrocatalytic efficiency for water remediation

Photoelectrocatalytic (PEC) degradation efficiency of refractory organic pollutants depends strongly on the characteristics of photoanode semiconductors. Therefore, choosing a photoanode semiconductor material to enhance the PEC efficiency is a critical problem. Here, we assemble a unique Co3O4@(δ-)MnO2 setaria-viridis-like heterostructure employing a two-step hydrothermal method. To maximize PEC degradation efficiency, coupling Co3O4 with an appropriate amount of MnO2 achieves Co3O4@MnO2-0.05, resulting in high oxygen evolution potential, fast carrier transfer, low resistance, electron-deficient surface, and high photo-response current. Those properties endow Co3O4@MnO2-0.05 as a promising candidate for practice application of dye degradation, with a degradation rate of ∼ 94.8 % and long-term durability (∼12000 s) under 1.0 mol·L−1 H2SO4 condition at a current density of 250 mA·cm−2 for blue KN-R degradation. Remarkably, the superior PEC degradation efficiency of Co3O4@MnO2-0.05 outperformed that of Co3O4-based and MnO2-based catalysts due to the dominant role of •O2− and h+ radical during degradation experiments.

Efficient photoelectrocatalytic degradation of azo-dyes over polypyrrole/titanium oxide/reduced graphene oxide electrodes under visible light: Performance evaluation and mechanism insights

Herein, polypyrrole/titanium oxide/reduced graphene oxide (PTi/r-GO) electrodes were prepared and successfully applied for the photoelectrocatalytic (PEC) degradation of methyl orange (MO) under visible light. Polypyrrole-TiO2 composites rich in p-n heterojunctions were first prepared, then modified with r-GO to improve the electrical conductivity and facilitate charge separation under visible light irradiation. The obtained PTi/r-GO composites were then deposited onto a titanium mesh, which served as the working electrode in PEC experiments. A MO removal efficiency of 93% was achieved in 50 min using PTi/r-GO electrode under PEC conditions (Xe lamp, λ > 420 nm, bias of 0.6 V, 0.1 M Na2SO4 electrolyte), which was far higher than MO removal efficiencies under electrocatalytic oxidation (22%) or photocatalytic oxidation (47%) conditions. This confirmed that excellent activity of the PTi/r-GO electrode under PEC conditions was due to a combination of electrochemical and photocatalytic oxidation processes (involving •OH and •O2− generation). Further, PTi/r-GO was very stable under the applied PEC conditions, with the MO removal efficiency remaining >90% after five cycles. PEC degradation pathways for MO on PTi/r-GO were explored, with a number of key intermediates in the MO mineralization process identified. Results demonstrate that PEC electrodes combining p-type polypyrrole, n-type TiO2 and rGO are very effective in the treatment of hazardous organic compounds in wastewater.

Understanding photoelectrocatalytic degradation of tetracycline over three-dimensional coral-like ZnO/BiVO4 nanocomposite

The coral-like BiVO4 was successfully constructed on ZnO nanorods grown on FTO substrates to reveal exceptional photoinduced charge migration kinetics as well as the underlying photoelectrocatalytic degradation process. The orderly ZnO nanorods array accelerated the separation of photogenerated carriers, while the three-dimensional coral structure of ZnO/BiVO4 nanocomposite increased the efficiency of light absorption and mass transfer, thus improving the photoelectrochemical properties. Fine interfacial contact between ZnO and BiVO4 led to the optimized photoelectrochemical performance with a photocurrent density of 0.29 mA/cm2 at 0 V vs. Ag/AgCl under visible light illumination (λ ≧ 420 nm), which was 3.2 times, 1.6 times of that of pristine ZnO and BiVO4. Moreover, the photoelectrocatalytic degradation efficiency of tetracycline from the ZnO/BiVO4 nanocomposite on was c. a. 84.5% and the main degradation paths were analyzed by LC-MS. Radical scavengers were employed to evaluate the capability to produce •O2− and •OH active species upon visible light illumination. This study elucidated the reaction mechanisms of the ZnO/BiVO4 nanocomposite during the photoelectrocatalytic degradation process.

Preparation of porous α-Fe2O3 thin films for efficient photoelectrocatalytic degradation of basic blue 41 dye

A novel method was developed for the preparation of porous hematite (α-Fe2O3) thin films. First, a solution containing iron precursor was spin-coated on fluorine-doped tin oxide substrate and later short heat-treated at 750 °C. The prepared α-Fe2O3 thin films were applied as dual-function catalyst in photoelectrochemical (PEC) water oxidation and textile dye degradation studies. For the first time, α-Fe2O3 thin films were used in efficient PEC degradation of a textile dye (Basic Blue 41 – B41) using in-situ generated reactive chlorine species. In comparison with photocatalytic and electrocatalytic approaches, the PEC technique allows faster degradation of B41 dye at an applied bias potential of 1.5 V versus reversible hydrogen electrode and under visible light illumination. In the presence of Cl− using the PEC approach the degradation of B41 reaches 99.8%. High-performance liquid chromatography coupled with UV–VIS system confirmed the degradation of B41 dye using PEC. Gas-chromatography coupled to mass spectrometry was used to study the by-products obtained during PEC degradation. Chemical oxygen demand analyses confirmed that the mineralization level of B41 is in the order of 68%. The α-Fe2O3 films developed in this study give a higher level of PEC degradation efficiency compared to other iron oxide-based systems.

Visible-light-driven photoelectrocatalytic degradation of p-chloronitrobenzene by BiOBr/TiO2 nanotube arrays photoelectrodes: Mechanisms, degradation pathway and DFT calculation

The BiOBr modified TiO2 nanotube arrays (BiOBr/TNAs) photoelectrodes were prepared for photoelectrocatalytic (PEC) degradation of p-chloronitrobenzene (p-CNB) under visible light irradiation. The surface structure analysis demonstrated that BiOBr nanoflakes were successfully deposited on the TNAs surface to form tight heterojunction. The BiOBr/TNAs photoelectrodes showed higher PEC degradation efficiency for p-CNB (71.96%) than that by bare TNAs (41.52%) owing to the improved visible-light absorption and reduced charges recombination. The hydroxyl radical and photogenerated holes were the main active species responsible for degradation, dechlorination and mineralization of p-CNB. The coexistence of dissolved anions and humic acid could decline p-CNB removal due to the radical scavengers or competition for active sites. The density functional theory (DFT) calculations indicated that the matched energy bands between BiOBr and TiO2 formed an internal electric field at the heterojunction interface, which promoted the charges migration and separation. The degradation mechanism and pathways of p-CNB were proposed based on the radical scavenging experiments, GC-MS spectra and theoretical calculations. The toxicity of identified intermediates from p-CNB was declined after PEC degradation.

Self-doping of Nb2O5NC by cathodic polarization for enhanced conductivity properties and photoelectrocatalytic performance

A simple novel electrochemical reduction approach was developed for the self-doping of Nb4+ in niobium oxide nanochannels (Nb2O5NC), changing the conductivity, optical properties, and photocatalytic properties of the material. Nb2O5NC was synthesized using different electrolytes: 0.4 wt% HF in 1 M H2SO4 (EI), 0.4 M NH4F in glycerol (EII), and 0.25 g NH4F with 4 vol% water in glycol at 50 °C (EIII). Field emission scanning electron microscopy (FEG-SEM) analysis showed well-organized arrays of Nb2O5 nanochannels produced on Nb foil, with varying tube diameters in the order EII < EI < EIII and film thickness in the order EI < EII < EIII, which drastically affected the photocurrent vs. potential curves. In order to self-dope the Nb2O5, the samples were electrochemically reduced in 0.1 M KH2PO4 buffer solution (pH 10) for 5 min, at −2.5 V vs. Ag/AgCl, resulting in the doped samples denoted P-EI, P-EII, and P-EIII. The results showed that reduction of Nb5+ to Nb4+ occurred for all the Nb2O5NC samples, leading to decreased surface charge transfer resistance between the Nb2O5NC and the electrolyte, as well as increases of the charge carrier density and photocurrent for all the self-doped samples, compared to undoped samples. Sample P-EI was also tested for the degradation of reactive red 120 (RR120) dye, achieving efficient photoelectrocatalytic degradation of a 10 mg L−1 dye solution. These results reveal that the self-doping approach can enhance the photoelectrocatalytic properties of Nb2O5 photoanode, offering an alternative way for the removal of reactive dyes.

Single-crystalline rutile TiO2 nanorod array on flexible Ti substrates for efficient photoelectrocatalytic degradation of phenol in water

Single-crystalline nanorods are intrinsic highways for charge transfer and hence ideal nanofeatures for efficient photoelectrochemical (PEC) degradations of pollutants in wastewater. Photocatalytic thin films on flexible substrates avoid the nuisance catalysts-recovering procedure and also allow for the flexible design in photocatalytic apparatus. We therefore directly deposited single-crystalline rutile TiO2 nanorod arrays on flexible and conductive Ti substrates through a hydrothermal technique and optimized the synthetic parameters to achieve an extremely high PEC activity towards phenol removal in water under UV light illumination. In the presence of tetrabutyltitanate (TBT) and HCl reactants under a hydrothermal environment, a balance in the erosion of the Ti substrate and the precipitation of TiO2 nanorods is found to be the key to tune the nanofeatures of the TiO2 thin films and in turn the PEC efficiency. The decreasing TBT concentration achieved a more sparsely distributed nanorod array, which significantly contributes to the PEC activity; yet too little TBT resulted in total dissolution of Ti plates. The PEC activity increased with increasing hydrothermal duration because of more loaded TiO2. The maximum reaction rate constant is 2.74 h−1, which is 39 times that of a commercial P25 TiO2 nanoparticulate film. The photocurrent stabilized at 0.9 mA/cm2 under the illumination of AM1.5G simulated solar light, suggesting a high separation efficiency of photogenerated holes and electrons along the single-crystalline rutile TiO2 nanorod arrays.

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-C3N4) modified TiO2 nanotube arrays (g-C3N4/TNAs) were prepared as the photoelectrodes for p-CNB degradation. The PEC degradation efficiency for p-CNB by g-C3N4/TNAs (0.00484 min−1) was much higher than that by bare TNAs (0.00135 min−1) under visible light. The g-C3N4/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-C3N4/TNAs photoelectrodes. The Z-scheme g-C3N4/TNAs provided an efficient approach for simultaneous dechlorination and mineralization of refractory pollutants.

Graphene oxide-promoted Ti/PbO2 photoanode with photoelectric synergy effect for efficient photoelectrocatalytic degradation of reactive brilliant blue

The development of semiconductor-based photoelectrocatalysts with superior activity is of great importance for water purification. Here, we fabricated graphene oxide (GO)-wrapped Ti/PbO2 photoanodes by combination of electrochemical deposition and electrophoretic deposition process. The as-obtained composite electrodes showed better performance for photoelectrocatalytic (PEC) degradation of reactive brilliant blue KN-R, as compared with that of Ti/PbO2 reference. Experimental results demonstrated that the efficient PEC performance of graphene oxide (GO)-wrapped Ti/PbO2 photoanodes could be ascribed to the low charge transfer resistance, large electrochemical active areas, and high separation efficiency of induced electrons/holes. Furthermore, a significant photoelectric synergy effect can be observed for the graphene oxide (GO)-wrapped Ti/PbO2 photoanodes during the photoelectrocatalytic process.

Efficient photoelectrocatalytic degradation of tylosin on TiO2 nanotube arrays with tunable phosphorus dopants

Photoelectrocatalytic (PEC) degradation of antibiotics residues is one of the most effective strategies for wastewater treatment. TiO2 has been widely used as an efficient photoelectrode material for pollutant removal. However, the degradation efficiency of UV light-driven TiO2-based photoelectrodes is still low. In this study, phosphorus-doped TiO2 nanotube arrays (TNTAs/P) were fabricated by calcination TNTAs with amorphous red phosphorus in sealed ampoules. By tuning the amount of P dopants, the optimized TNTAs/P(0.75) photoelectrode exhibits excellent PEC degradation performance under the Xenon lamp (100 mW/cm2, λ > 300 nm) light irradiation, with 79 % tylosin removal within 250 min.. The TNTAs/P(0.75) photoelectrode also displays about 4-fold photocurrent enhancement than bare TNTAs. It is suggested that the P-doping treatment could improve the light-harvesting ability and accelerate the separation efficiency of photo-induced electron-hole pairs in TNTAs, which benefits the production of •OH radicals and thus leads to the enhancement in tylosin degradation activity. This present work demonstrates a facile approach for improving the PEC degradation efficiency by doping heteroatoms in the photoelectrode.Capsule: P-doped TiO2 nanotube arrays were fabricated for boosting photoelectrocatalytic tylosin degradation activity due to the enhanced light absorption and charge transfer efficiency.

Heterojunction architecture of pTTh nanoflowers with CuOx nanoparticles hybridized for efficient photoelectrocatalytic degradation of organic pollutants

Herein, resulting from the heterojunction engineering, poly-terthiophene (pTTh) hybridized CuOxnanoparticles (abbreviated as CuOx@pTTh) are firstly synthesized and adopted as a promising photoelectrocatalyst for phenol degradation in wastewater. The resultant CuOx@pTTh manifests outstanding light-harvesting ability and remarkable capacity to separate photo-generated electron-hole pairs for phenol degradation in aqueous solution. X-ray photoelectron (XPS) characterizations and theoretical calculations further identify that there exists a strong electronic interaction between CuOx nanoparticles and pTTh, further enhancing the charge carriers transfer dynamics of the as-prepared catalysts. Electron spin resonance (ESR) spectroscopy and high performance liquid chromatography (HPLC) are applied to explore the active species and the degradation mechanism of photoelectrocatalyis (PEC) reactions. It is found that in PEC degradation of phenol the main active species are ·O2− and ·OH. Also, it can be concluded that phenol can eventually be step by step oxidized to CO2 and H2O through different pathways, according to the different detected intermediates.

Efficient Photoelectrocatalytic Degradation of BTEX Using TiO2/CuO/Cu2O Nanorod-Array Film as the Photoanode and MWCNT/GO/Graphite Felt as the Photocathode

Wastewater treatment challenges by conventional methods have necessitated the need for alternative/complementary methods that are environmentally safe and efficient especially towards recalcitrant organic pollutants. In this regard, a novel highly active visible-light responsive photoanode with the ternary hybrid CuO/Cu2O/TiO2 nanorods array film is proposed to enhance electron transfer in the photoelectrocatalytic (PEC) degradation of BTEX (benzene, toluene, ethyl benzene, and xylenes) by combining with MWCNT/GO/GF cathode. Structural, morphological, optical, electrochemical, and elemental analysis of proposed electrodes is investigated in detail. Response surface methodology (RSM) comprising of full-factorial central composite design (CCD) with five factors and five levels has been used to examine the effects of different operating parameters such as electrode distance, current density, treatment time (t), solution pH, and conductivity in a PEC batch reactor. BTEX mineralization in aqueous solution was examined with multiple responses such as chemical oxygen demand (COD) and specific energy consumption. During multiple response optimization, the desirability function approach was employed to concurrently maximize COD removal and minimize energy consumption. At the optimum condition, 81.3% COD removal and 9.5 kWh/kg of COD removed were observed. The photoelectrocatalytic oxidization mechanism of BTEX with proposed anode and cathode was discussed, then the possible degradation pathway of BTEX identified using GC–MS.

Optimization of Degradation Kinetics towards O-CP in H3PW12O40/TiO2 Photoelectrocatalytic System

Kinetics is crucial for photoelectrocatalytic degradation of organic contaminants. A 12-tungstophosphoric acid/titania (H3PW12O40/TiO2) composite film was prepared by the sol-gel-hydrothermal route to investigate the optimal conditions and degradation kinetics of o-chlorophenol (o-CP). The photoelectrocatalytic degradation efficiency of o-CP was 96.6% after 180 min under optimum conditions (impressed voltage: 0.5 V, solution pH: 6.3, and initial concentration: 5 mg·L−1), and the apparent kinetics constant (K’) was a 6.0-fold increase compared to the photocatalytic system. Furthermore, the photoeletrocatalytic reaction rate of o-CP by H3PW12O40/TiO2 and TiO2 film was 0.090 and 0.020 mg·L−1·min−1, respectively, and a higher apparent quantum yield (Φ = 32.14%) of H3PW12O40/TiO2 composite film was attained compared to TiO2 film (Φ = 10.00%), owing to the fact that more photo-generated carriers were produced and effectively separated. Intermediate products identified during o-CP degradation by liquid chromatography-mass spectrometer (LC-MS) were 2-Chlorohydroquinone (CHQ), catechol (CT), and hydroxyl-hydroquinone (H-HQ). The H3PW12O40/TiO2 photoelectrocatalytic system exhibited outstanding potential for the removal of chlorinated organic contaminants in wastewater.

Enhancement of azo dye degradation and power generation in a photoelectrocatalytic microbial fuel cell by simple cathodic reduction on titania nanotube arrays electrode

The research provides a simple method for high-performance electrode preparation for use with a microbial fuel cell and microcurrent to treat pollutants. Blue titania nanotube arrays as a new microbial fuel cell electrode is synthesized by cathodic reduction. The results show that these arrays remarkably increase the electricity generation from 3.64 ± 0.112 mA to 6.246 ± 0.135 mA at the bioanode. A higher carrier concentration of 4.70 × 1024 cm−3, an apparent electron transfer rate constants of 21.69 ms−1 and drastic decrease in resistance to 1352 Ω provide better conditions for electroactive bacteria accumulation. The application of blue titania nanotube arrays to both the anode and cathode results in a photo-microbial fuel cell capable of efficient photoelectrocatalytic degradation of azo dye. The degradation of the azo dye and its intermediate products is attributed to electronic reduction of the dye and oxidation by free radicals.

Novel ZnFe2O4/TiO2/flake graphite composite as particle electrodes for efficient photoelectrocatalytic degradation of rhodamine B in water.

A novel ZnFe2O4/TiO2/flake graphite composite material was synthesized and used as particle electrodes in a photoelectrocatalytic (PEC) system to investigate the degradation of rhodamine B as a model dye pollutant in water. Results showed that a PEC process with the new composite evidently led to enhanced degradation of rhodamine B due to a synergistic effect of photocatalysis and electrocatalysis. Operating variables including electrolyte concentration, applied cell voltage, air flow, composite dosage, solution pH, and dye concentration were also found to play important roles in rhodamine B removal. A 99.0% removal efficiency was observed within 30 min of treatment under optimum conditions of 0.01 mol/L Na2SO4, applied cell voltage of 15 V, air flow of 20 mL/min, composite dosage of 10 g/L, solution pH of 2, and rhodamine B concentration of 20 mg/L, with a pseudo-first-order rate constant of 0.278 min-1. These findings could provide new insights into the development of efficient PEC technologies on degradation of residual dyes in water.

Peroxymonosulfate enhanced photoelectrocatalytic degradation of phenol activated by Co 3 O 4 loaded carbon fiber cathode

Abstract In this paper, a photoelectrocatalytic (PEC) system consisting of γ-Bi 2 MoO 6 anode and Co 3 O 4 loaded carbon fiber paper (Co 3 O 4 /CFP) cathode prepared by a hydrothermal method was established and used to degrade phenol. In order to enhance the PEC degradation efficiency of phenol, peroxymonosulfate (PMS) was introduced into this system. At an applied bias of 1.5 V, the removal efficiency of 10 mg/L phenol was increased from 6% to 100% with 2 mM PMS addition into the PEC process. The degradation rate constant of phenol was also increased to be 0.0496 min −1 . Effects of PMS concentration, applied bias and initial pH were investigated. Based on the ESR analysis, sulfate radicals (SO 4 − ) and hydroxyl radicals (HO ) were proved to be the dominant oxidizing species for phenol degradation in the combined system. The PMS was activated to generate SO 4 − by loaded Co 3 O 4 , in which photogenerated-electrons accelerated the cobalt cycle process on the cathode. As a result, Co leaching was largely inhibited. The stability of the PEC system for organics degradation was exhibited.

H2O2 assisted photoelectrocatalytic degradation of diclofenac sodium at g-C3N4/BiVO4 photoanode under visible light irradiation

In this paper, g-C3N4/BiVO4 composite was electrospinned onto FTO substrate and used as photoanode for photoelectrocatalytic degradation of diclofenac sodium. The photoelectrocatalytic degradation efficiency of DCF by the g-C3N4/BiVO4 photoanode is much higher than that by the individual g-C3N4 and BiVO4 photoanodes. The first order kinetic constants are estimated to be 3.2×10−3min−1 for g-C3N4/BiVO4 photoanode, while the kinetic constants are 1×10−4min−1 and 1.1×10−3min−1 for g-C3N4 and BiVO4 photoanode. To further increase the degradation of DCF in PEC process, H2O2 was added into the system, and the results indicated that DCF degradation was largely increased. The kinetic rate constant was 5.6×10−3min−1 for H2O2 assisted PEC process and it was estimated to be 3.2×10−3min−1 and 1×10−5min−1 for the individual PEC process and H2O2 oxidation process, respectively. Effect of initial pH, H2O2 dosage and applied bias on DCF degradation was investigated in detail. The highest DCF degradation efficiency was achieved at initial pH of 3.17 and applied bias potential of 1.0V (vs. SCE) with 10mM H2O2 addition. Involved reactive active species were studied using electron spin resonance; a proposed reaction pathway was proposed.

The effect of different exposed facets on the photoelectrocatalytic degradation of o-chlorophenol using p-type Cu2O crystals

Although it is known that the efficacy of photoelectrocatalysts is enhanced by increasing the amount of high energy surface exposed, the development of a universal synthesis method with both superior activity and simplicity is needed for scalable applications. We herein controllably fabricated cuprous oxide (Cu2O) micro crystals with different morphologies, evolving from cubes, cuboctahedra, truncated octahedra and finally to octahedra on indium tin oxide (ITO) glass substrates, by a facile electrochemical deposition method. The structures of facet-engineered Cu2O samples and the underlying mechanism for the morphology evolution were investigated. The separation of photogenerated hole-electron pairs on Cu2O crystals with different exposed facets was characterized by measuring the photocurrent densities with chopped illumination, which increased with the increased concentrations of PVP: the octahedral Cu2O crystals, with the highest proportion of {111} facets exposed, exhibited the lowest electro-hole recombination in contrast to the cubes, cuboctahedra, and truncated octahedra, respectively. The photoelectrocatalytic degradation efficiency of the o-chlorophenol (2-CP) pollutant under sunlight irradiation with Cu2O-coated photocathode was further investigated to reveal the effect of different exposed facets. Due to the increased number of surface active sites available for degradation reactions, the octahedral Cu2O microcrystals presented higher photoelectrocatalytic activity compared to other shapes. Active oxygen species detected by electron spin-resonance (ESR) spectrometry implied that abundant superoxide radicals (O2●−) were the dominant active radicals in the degradation.

A TiO2-nanotubes-based coil-type microreactor for highly efficient photoelectrocatalytic degradation of organic compounds

Abstract A continuous-flow, coil-type photoelectrocatalytic microreactor for the degradation of caffeine was designed, assembled and characterized. Its main components are the photocatalytically active anode and the cathode coils, which are wrapped around a silica-glass rod and placed into a UV-transparent housing. The anode coil was prepared by anodic oxidation of the titanium coil, which leads to the formation of vertically aligned, titanium dioxide, nanotube arrays that exhibit a high photocatalytic activity and are rigidly attached to the titanium wire. The photocatalytic, electrocatalytic and photoelectrocatalytic activities of the assembled microreactor were measured systematically while changing the main parameters that affect the device’s efficiency. The most significant change in the microreactor’s design in terms of efficiency was to place the cathode coils on both sides of the anode coil, which resulted in the shortest time for complete degradation of the caffeine. When an applied anodic bias potential of 4 V was used in the most efficient microreactor design, 1 mL of the 40 mg/L caffeine was fully decomposed in 55 min.

Efficient Solar Energy Conversion Using CaCu3Ti4O12 Photoanode for Photocatalysis and Photoelectrocatalysis.

A highly efficient third generation catalyst, CaCu3Ti4O12 (CCTO) shows excellent photoelectrochemical (PEC) and photocatalytic ability. As only 4% part of the solar spectrum covers UV light, thus it is highly desirable to develop visible light active photocatalyst materials like CCTO for effective solar energy conversion. A direct band transition with a narrow band gap (1.5 eV) was observed. Under light irradiation, high photocurrent density was found to be 0.96 mA/cm2, indicating the visible light induced photocatalytic ability of CCTO. Visible light mediated photocatalytic and photoelectrocatalytic degradation efficiency of CaCu3Ti4O12 pellets (CCTO) was investigated for three classes of pharmaceutical waste: erythrosin (dye), ciprofloxacin (antibiotic) and estriol (steroid). It is found that the degradation process follows first order kinetic reaction in electrocatalysis, photocatalysis and photoelectrocatalysis and high kinetic rate constant was observed in photoelectrocatalysis. This was quite high in comparison to previously reported methods.