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Intrinsic Au-decoration on anodic TiO2 nanotubes grown from metastable Ti–Au sputtered alloys—High density co-catalyst decoration enhances the photocatalytic H2 evolution
摘要： Recent work demonstrated that intrinsic Au nanoparticle decoration of TiO2 nanotube arrays (NTs) can be achieved by electrochemical anodization of Ti–Au alloy substrates. However, for a Ti–Au cast alloy produced by melt-alloying, the Au concentration cannot exceed the solubility limit of Au in Ti of 0.2 at.% – this sets constraints on the intrinsic Au nanoparticle loading on anodic TiO2 NTs. Here we explore “metastable” Ti–Au metal substrates that are produced by Ti and Au cosputtering and we establish Au concentrations that far exceed the solubility limit in cast Ti–Au alloys. We show the use of these “metastable” Ti–Au sputtered layers for the anodic formation of TiO2 NTs with a much higher density of Au nanoparticle loading than using classic alloys. Under optimized conditions (Au nanoparticle density) photocatalytic H2 production from such Au@TiO2 platforms provides a 15 times higher photocatalytic H2 evolution rate than the best rates achieved with conventional alloys.
关键词： Anodic TiO2 nanotube,Metastable Ti–Au alloy,Sputtering,Anodization,Photocatalytic H2 evolution
更新于2025-09-23 15:23:52
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Organic/inorganic nitride heterostructure for efficient photocatalytic oxygen evolution
摘要： Given the four-electron water oxidation reaction as the rate-limiting step for water splitting, highly efficient photocatalysts for oxygen evolution have been receiving increasing research attentions. In this study, an organic/inorganic g-C3N4/CoN nitride heterostructure was developed by a facile precipitation-nitridation two-step process. With the CoN loading amounts optimized, the obtained g-C3N4/CoN composite achieves more than 4-fold increase in photocatalytic activity for oxygen evolution, as compared to the pristine g-C3N4, with a highest oxygen evolution rate reaching 607.2 μmol h?1 g?1 under visible light (λ > 420 nm). It was demonstrated that the formed g-C3N4/CoN heterostructure could promote the interfacial charge carrier separation and the loaded CoN acting as an effective cocatalyst could accelerate the water oxidation reaction kinetics, which synergistically contributes to the great enhancement in photocatalytic activity for oxygen evolution. Interestingly, by physically mixing g-C3N4/CoN and g-C3N4/Ni, acting as oxygen and hydrogen production photocatalysts, respectively, the obtained composite could stably produce oxygen and hydrogen in the stoichiometric ratio from pure water under visible light (λ > 420 nm). Although the photocatalytic overall water splitting activity is still very low, this study demonstrates a facile and promising approach to develop visible-light active photocatalysts for simultaneous hydrogen and oxygen production from water, from the perspective of surface modification and bifunctional cocatalyst loading.
关键词： Oxygen evolution,g-C3N4,Photocatalytic water splitting,Heterostructures
更新于2025-09-23 15:23:52
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Skeletal tailoring of two-dimensional π-conjugated polymer (g-C3N4) through sodium salt for solar-light driven photocatalysis
摘要： Structural modi?cation of graphitic carbon nitride (g-C3N4) by addition of sodium salt has been investigated for solar light-driven photocatalysis. The results from optical study indicates that the incorporation of sodium ions decreases band gap energy along with upward shifts of conduction and valence band. However, no substantial increment in surface area was observed, but morphological and optical studies con?rm that the structural deformation of g-C3N4 through sodium salt activates the ?n π * electronic transition, which can extend the absorption range to the red region attributing towards a reduced charge recombination, narrow band gap, and high conduction band edge. Furthermore, the photocatalytic activity of sodium doped g-C3N4 (0.6Na-g-C3N4) was examined under solar light for di?erent operational conditions in terms of phenol degradation of real tannery e?uent, and it was found that under optimum experimental conditions, i.e., 5 h solar irradiance, pH 5, H2O2 concentration 800 mg/L with a ?ow rate of 4 L/h, 0.6 Na- g-C3N4 exhibits 84.22% reduction in phenol while for g-C3N4 only 63.53% was observed.
关键词： Graphitic carbon nitride,Photocatalytic activity,Charge recombination,Solar irradiance,Band gap,Sodium salt
更新于2025-09-23 15:23:52
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Construction of CuInS2@ZIF-8 nanocomposites with enhanced photocatalytic activity and durability
摘要： Inspired by the unique structure and wide applications of zeolitic imidazolate frameworks-8 (ZIF-8) and CuInS2 (CIS), considerable attention has focused on the combination of both materials. We herein report a facial method for the homogeneous decoration of ZIF-8 onto the surfaces of CuInS2 (CIS) nanoparticles coordinated by poly-vinyl pyrrolidone (PVP) in methanol. It has been shown that the coordination of PVP plays a key role in inducing the nucleation of ZIF-8 on the surface of CIS nanoparticles because of the pyrrolidone rings (C = O) in PVP offering an improved affinity between CIS and Zn ions. Performing as a catalyst, the CIS@ZIF-8 nanocomposites not only exhibit high photocatalytic activity for the degradation of organic dye under UV light irradiation, but also largely maintain their catalytic efficiency after being recycled for five times compared with that of pure CIS nanoparticles.
关键词： Photocatalytic properties,Semiconductors,CuInS2@ZIF-8,Nanocomposites
更新于2025-09-23 15:23:52
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Removal of pharmaceutically active compounds (PhACs) from real membrane bioreactor (MBR) effluents by photocatalytic degradation using composite Ag2O /P-25 photocatalyst
摘要： Pharmaceutically active compounds (PhACs) are emerging pollutants causing serious challenges to wastewater treatment plants due to poor biodegradability. In this study, the enhanced removal of highly recalcitrant and commonly monitored PhACs, carbamazepine (CBZ) and diclofenac (DCF) by heterogeneous photocatalysis was investigated using 5% Ag2O /P-25 photocatalyst. The photocatalyst was characterized by scanning electron microscope (SEM-EDX), Brunauer-Emmett-Teller (BET), and UV-vis diffuse reflectance spectra (UV-DRS). The effects of catalyst dose, initial pollutants concentration, and mineralization during the photocatalytic degradation of PhACs were investigated. The matrix effect was assessed in deionized water (DW) and real membrane bioreactor effluent (RME). Optimal CBZ and DCF removals of 89.10 % and 93.5 %, respectively for 180 min of UV irradiation were achieved at catalyst dosage of 0.4 g L-1 in DW matrix. However, the optimal catalyst dosages for CBZ and DCF in RME matrix were increased by factor 2 and 1.5, respectively, to achieve the same degree of removal. Declining trends of removal rate were observed when initial concentrations of both the PhACs were increased under optimal catalyst dosages, and kinetics seem to fit the Langmuir-Hinshelwood model. Photo-induced holes and ?OH were the dominant oxidation species involved in the photocatalytic degradation of the PhACs. A plausible reusability of 5% Ag2O /P-25 photocatalyst was observed for both the PhACs. Moreover, various aromatic/aliphatic intermediates generated during the photodegradation CBZ were identified using fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometry, and a possible multi-step degradation pathway was proposed. Overall, the removal of PhACs using 5% Ag2O /P-25 photocatalyst showed promising results in real wastewater.
关键词： PhACs,transformation products,Ag2O/P-25 photocatalysts,matrix effect,photocatalytic degradation
更新于2025-09-23 15:23:52
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Photocatalytic degradation of pharmaceutical micro-pollutants using ZnO
摘要： This research paper presents the results of an experimental investigation of the degradation of three different contaminants including progesterone (PGS), ibuprofen (IBU), and naproxen (NAP) using ZnO as the photocatalyst and ultraviolet (UV) light as a source for catalysts activation. Two operating parameters, namely, catalyst loading and initial concentration of contaminants, were tested in a batch photocatalytic reactor. To demonstrate the large-scale applications, experiments were also conducted in a submerged membrane photocatalytic reactor. It has proven that ZnO photocatalyst degraded the three contaminants very efficiently under almost all the studied experimental conditions, with efficiency rates of 92.3, 94.5, and 98.7 % for PSG, IBU, and NAP, respectively. The photodegradation kinetics study was performed to calculate the reaction rate constant, which is found to follow pseudo-first order kinetics. The membrane photocatalytic reactor was efficient to remove pollutants and it is observed that the degradation rate increases with increasing the membrane oscillation frequency approaching that of the stirred reactor.
关键词： Photocatalytic degradation,Progesterone,Ibuprofen,Photocatalytic batch reactor,Naproxen,Oscillatory membrane reactor,ZnO
更新于2025-09-23 15:22:29
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Preparation of MoS <sub/>2</sub> @ZnO heterostructure with enhanced photocatalytic activity
摘要： In order to effectively solve environmental problems induced by organic pollutants, the MoS2@ZnO heterostructure is successfully fabricated via a two-step hydrothermal method, in which the MoS2 nanosheets grew on the surface of ZnO nanorods. The synthetic heterostructure is demonstrated to possess excellent photocatalytic activity in the degradation of methylene blue (MB) under ultraviolet (UV) and visible light irradiation. The corresponding photodegradation rate constant of MoS2@ZnO heterostructure reaches up to 0.02075 min-1 and 0.00916 min-1, which are higher than that of pure ZnO (0.00514 min-1 and 0.00048 min-1) under the same reaction conditions. Obviously, compared with pure ZnO, the photocatalytic activity of the MoS2@ZnO heterostructure has been significantly improved. This could be attributed to the increased specific surface area of photocatalyst and the formation of heterostructure between ZnO and MoS2 after loading the MoS2 on the surface of ZnO nanorods. Which help to provide more reaction sites for the adsorption of pollutant and improve the separation efficiency of photogenerated electron-hole pairs.
关键词： MoS2,composite materials,ZnO,photocatalytic activity,heterostructure
更新于2025-09-23 15:22:29
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Hierarchical Fe2O3 nanorods/TiO2 nanosheets heterostructure: Growth mechanism, enhanced visible-light photocatalytic and photoelectrochemical performances
摘要： A novel three-dimensional (3D) Fe2O3 nanorods (NRs)/TiO2 nanosheets (NSs) heterostructure is fabricated by employing the TiO2 NSs with dominant high-energy {0 0 1} facets as synthetic template via the facile hydrothermal and chemical bath deposition methods. The structure, morphology and optical property of 3D Fe2O3/TiO2 composites are examined, and the results demonstrate that these samples have pure phase, high crystallinity and good visible-light response. Furthermore, all Fe2O3/TiO2 composites exhibit the superior photocatalytic and photoelectrochemical (PEC) performances compared to pure TiO2 NSs, which should be ascribed to the larger surface area, better optical absorption and efficient electron-hole separation of 3D Fe2O3/TiO2 heterostructure. Among Fe2O3/TiO2 composites, the sample T3 obtained by using 0.05 M iron nitrate at 90 °C for 100 min exhibited the best visible-light photocatalytic activity and PEC performance, which achieves 89.3% photodegradation of Methyl Blue within 120 min and 2.39 mA cm?2 photocurrent density at a potential of 0 V, respectively. The photocatalytic degradation efficiency and photocurrent density of T3 are 1.83 and 11.95 times higher than that of pure TiO2 NSs. In addition, the detailed growth mechanism of Fe2O3 nanomaterials onto TiO2 NSs and the optimization mechanism of photocatalytic and PEC performances are also discussed in present paper.
关键词： Photoelectrochemical,Photocatalytic,Visible-light,TiO2 nanosheets,Fe2O3/TiO2 heterostructure
更新于2025-09-23 15:22:29
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Photocatalytic toluene degradation over Bi-decorated TiO2: Promoted O2 supply to catalyst’s surface by metallic Bi
摘要： In the photocatalytic volatile organic compounds (VOCs) degradation, the accumulation of intermediate products on the surface of catalysts could cause a decrease in activity through retarding reactant (e.g. O2) supply to surface active sites. Herein, Bi decorated TiO2 photocatalysts (Bi/TiO2) for photocatalytic toluene degradation were prepared and systematically studied. It is found that metallic Bi modification improves the ability of photocatalysts to capture O2. As a result, the activities of the Bi/TiO2 photocatalysts are obviously higher than that of the TiO2 for photocatalytic toluene degradation, and the productions of photogenerated reactive oxygen species (O2? and H2O2) over the Bi/TiO2 photocatalysts are almost equal to that over the TiO2 despite the fact that the separation efficiency of photoinduced charge carriers is decreased after the addition of Bi. Adsorbed benzaldehyde is the main surface intermediate on the surface of the Bi/TiO2 photocatalysts, whereas plenty of more readily oxidized aliphatic carboxylate species was monitored on the surface of the TiO2, which can be attributed to insufficient O2 supply to the TiO2 surface. This further indicates the positive role of the promoted O2 supply by Bi in the photocatalytic toluene degradation. The present work offers a new window for addressing the catalyst deactivation in the photocatalytic VOCs degradation.
关键词： The uptake of O2,Intermediate products,Metallic Bi,Photocatalytic VOCs degradation
更新于2025-09-23 15:22:29
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Composite materials based on active carbon/TiO2 for photocatalytic water purification
摘要： The present work describes the preparations of active carbon (AC) – titania composites with different AC/TiO2 ratio, their characterization using XRD, BET and SEM and evaluation of adsorption capacity and photocatalytic activity in aqueous solution using azo-dye Acid Orange 7 (AO7). Composite materials based on AC/TiO2 were prepared from commercial active carbon (1737 m2/g) and TiO2 (P25, 45 m2/g) materials by the mixing method. The studied parameters were the ratio of AC/TiO2, hydrothermal treatment and milling of as-prepared composites. The composites show increased BET surface area proportional to the content of AC in the material. The disappearance of AO7 is due to the combination two processes, e. g. adsorption and photocatalytic oxidation which takes place in parallel. Thus the overall removal of AO7 has been corrected on adsorption (measured in dark) to obtain the rate of AO7 disappearance due to photocatalytic oxidation (PO). The optimum ratio of AC/TiO2 was found to be 0.23 where PO rate is only slightly lower than that for P25 and overall AO7 removal is twice higher than for P25 itself. The less intensive (low-frequency) milling of the composite results in the decrease of carbon particle size, increase in AO7 adsorption and decline in the PO of AO7. More intensive milling (high-frequency) results in the decrease of the anatase content, appearance of the small amount of brookite and almost negligible PO rate of AO7. Irradiation of low-frequency milled AC/TiO2 composite in aqueous suspensions resulted in the generation of a comparable concentration of hydroxyl radical spin-adduct (?DMPO-OH) as non-milled composite, high-frequency milled composite revealed substantially lower ?DMPO-OH concentration which can be explained by the increased concentration of carbon-centered radicals in AC acting as scavengers of photogenerated electrons.
关键词： adsorption,Active carbon,P25,EPR spectroscopy,AO7,photocatalytic oxidation
更新于2025-09-23 15:22:29