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•Direct Z-scheme g-C3N4/TiO2 (nanoparticle and nanotube) photocatalysts were prepared.•Photocatalytic activity was evaluated by degradation of isoniazid pharmaceutical.•Composite with ...CN facilitated electron–hole pair separation by Z-scheme mechanism.•Direct Z-scheme g-C3N4/TNT showed higher photocatalytic activity than g-C3N4/TNP.•TiO2 morphology (nanotube) has significant influence on the photocatalytic activity.
Direct Z-scheme graphitic carbon nitride (g-C3N4)/TiO2 (nanoparticle and nanotube) photocatalysts with different g-C3N4 loadings were prepared using a facile wetness impregnation method. TiO2 nanotubes were synthesized using a hydrothermal method. The influence of the TiO2 morphology on the photocatalytic efficiency of the direct Z-scheme g-C3N4/TiO2 photocatalysts was studied through the photodegradation of isoniazid. The firm connection between g-C3N4 and TiO2 was investigated using powder X-ray powder diffraction, field emission-scanning electron microscopy, transmission electron microscopy, X-ray photoelectron and Fourier-transform infrared spectroscopy. Subsequently, both the direct Z-scheme photocatalysts were used for the decomposition of isoniazid. Our results revealed that the Z-scheme g-C3N4/TiO2 nanotube (3%-CN/TNT) photocatalyst exhibited enhanced (90.8%, 4h) photocatalytic activity, and the g-C3N4/TiO2 nanoparticles (5%-CN/TNP) had a higher activity (79.5%, 4h) than the photocatalysts with other g-C3N4 loadings, TiO2 nanotubes (73.3%, 4h), TiO2 nanoparticles (56.3%, 4h), and g-C3N4 (13.5%, 4h). Presumably the enhancement of photocatalytic activity was due to effective separation of the charge carriers between g-C3N4 and TiO2 through the Z-scheme mechanism. The separation of the charge carriers was confirmed using photoluminescence and photocurrent measurements. A direct Z-scheme charge transfer process was confirmed through free radicals (h+, OH, and O2−) scavenging and hydroxyl (OH) radical determination studies. The enhanced OH radical generation using 3%-CN/TNT photocatalyst could also lead to enhanced photocatalytic performance than the other photocatalysts. We proposed a mechanism for the enhanced photocatalytic activity and the probable degradation pathway for isoniazid. Further confirmation of the isoniazid degradation was performed using kinetic studies and chemical oxygen demand analysis. Our results suggested that the TiO2 morphology significantly influenced the photocatalytic efficiency of the direct Z-scheme photocatalysts under our reaction conditions.
Summary
Lanthanum ferrite decorated reduced graphene oxide (LaFeO3/rGO) nanocomposite is prepared by in‐situ microwave irradiation method. The X‐ray diffraction study reveals the single phase ...orthorhombic structure of LaFeO3 nanoparticles and LaFeO3/rGO nanocomposites. The FTIR study reveals various vibrational modes and the characteristic D and G bands of the Raman spectrum confirms the formation of reduced graphene oxide. The SEM and HR‐TEM images demonstrate that spherical LaFeO3 particles are decorated on 2D graphene sheets. From the HR‐TEM study, the average particle size of LaFeO3 is estimated to be 23 nm. The synergistic effect of 3D LaFeO3 nanoparticles and 2D graphene layers offers more active sites to achieve the enhanced electrochemical performance. The specific capacitance of LaFeO3/rGO composites is measured to be 170 Fg−1 at 10 mV s−1. The composite electrode has admirable cyclic stability, better Columbic efficiency and improved capacitance retention with great potential for supercapacitor applications.
Novelty of the present investigation is to synthesis LaFeO3/rGO nanocomposite by low cost in‐situ microwave irradiation method. Uniform decoration of LaFeO3 nanoparticles on the 2D graphene sheets provides more stability of the electrode. The prepared composite electrode material demonstrates higher specific capacitance, Strong cyclic stability and improved capacitive retention.
The increasing energy demands in society and industrial sectors have inspired the search for alternative energy sources that are renewable and sustainable, also driving the development of clean ...energy storage and delivery systems. Various solid-state materials (
, oxides, sulphides, polymer and conductive nanomaterials, activated carbon and their composites) have been developed for energy production (water splitting-H
production), gaseous fuel (H
and CH
) storage and electrochemical energy storage (batteries and supercapacitors) applications. Nevertheless, the low surface area, pore volume and conductivity, and poor physical and chemical stability of the reported materials have resulted in higher requirements and challenges in the development of energy production and energy storage technologies. Thus, to overcome these issues, the development of metal-organic frameworks (MOFs) has attracted significant attention. MOFs are a class of porous materials with extremely high porosity and surface area, structural diversity, multifunctionality, and chemical and structural stability, and thus they can be used in a wide range of applications. In the present review, we precisely discuss the interesting properties of MOFs and the various methodologies for their synthesis, and also the future dependence on the valorization of solid waste for the recovery of metals and organic ligands for the synthesis of new classes of MOFs. Subsequently, the utilization of these interesting characteristics for energy production (water splitting), storage of gaseous fuels (H
and CH
), and electrochemical storage (batteries and supercapacitors) applications are described. However, although MOFs are efficient materials with versatile uses, they still have many challenges, limiting their practical applications. Therefore, finally, we highlight the challenges associated with MOFs and show the way forward in overcoming them for the development of these highly porous materials with large-scale practical utility.
UV-light emitting diodes (UV-LEDs) was used for the photocatalytic degradation of Rhodamine B (RhB) dye to study the various parameters, effectiveness and feasibility for designing of photocatalytic ...reactor based on UV-LED irradiation in different conditions. The photocatalytic experiments were conducted using 5 UV-LED lights with same specification and Degussa P-25 TiO₂ as a photocatalyst. The effects of operational parameters such as catalysts loading, initial dye concentration, pH, addition of H₂O₂ and effect of metal ions (Zn²⁺, Ag⁺, Fe³⁺, Cu²⁺ and Cd²⁺) were studied for the photocatalytic degradation of RhB. A detailed degradation pathway has been suggested, which was based on the electrospray ionization mass spectrometry (ESI-MS) analysis. It was observed that the degradation of RhB occurred via N-de-ethylation process. N-de-ethylated product was further oxidized into acids and alcohols. The complete mineralization of RhB dye (2.08×10⁻⁵M) was confirmed by chemical oxygen demand (COD), total organic carbon (TOC), total inorganic carbon (TIC) and high pressure liquid chromatography (HPLC) analysis. The optimum conditions for higher percentage degradation of RhB dye obtained with amount of catalyst (1.6g/L), dye concentration (6.26×10⁻⁵M) and pH=3.05. Results demonstrated that the UV-LED/TiO₂ process can effectively degrade RhB dye with optimum conditions.
Bismuth-doped TiO
2
nanotubes (Bi-TNT) were successfully synthesized by combination of sol–gel and hydrothermal methods. The synthesized photocatalyst was efficiently used for degradation of ...rhodamine B (RhB) dye under direct sunlight irradiation. Subsequent characterization of synthesized photocatalysts was carried out using PXRD, SEM, TEM, EDX, FT-IR, Raman, N
2
adsorption, TPD-NH
3
, UV–Vis DRS, XRF and ICP techniques. The surface area of the TiO
2
nanoparticles increased after tubular structure formation (TiO
2
nanoparticles—114.21 m
2
/g, TiO
2
nanotube—191.93 m
2
/g). The degradation studies revealed that initial rate of photocatalytic degradation of RhB dye using Bi-TNT was 5.56, 4.16, 1.30 and 2.38 times higher as compared to TNP, Bi-TNP, TNT and Degussa P-25 TiO
2
(P-25), respectively, under direct sunlight irradiation. The enhanced photocatalytic activity of Bi-TNT may be due to the increase in the surface area and Bi doping, which leads to effective separation of photogenerated carriers. The degradation was confirmed by chemical oxygen demand, total organic carbon and total inorganic carbon analysis of the degraded dye solutions. The probable degradation mechanism of RhB dye has also been proposed using liquid chromatography-mass spectrometry analysis of degraded samples.
The present study focuses on the development and feasibility of ultraviolet light emitting diode (UV-LED) source and TiO2 nanotube array (TNA)-based photocatalytic reactor for Congo red (CR) dye ...degradation. Highly ordered TNA was synthesized by the anodization method. The synthesized highly ordered TNA was characterized by X- ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscope (AFM), and electronic impedance spectroscopy (EIS) techniques. The percentage degradation was determined using a UV–visible spectrophotometer, while the mineralization of CR dye was further confirmed by chemical oxygen demand (COD) and kinetic analysis. The effect of operational parameters such as initial concentration of dye and pH on the degradation of CR dye has been studied to determine the optimum conditions. A possible degradation mechanism based on the electrospray ionization mass spectrometry (ESI-MS) has been suggested. The results demonstrated that CR dye was completely degraded in 5 h using the designed photocatalytic reactor. The electrical energy per order (E Eo) was calculated for estimating the electrical energy efficiency. The result demonstrated that highly adhered nanotube array can effectively be used for photocatalytic degradation of CR dye in the presence of UV-LED light irradiation.
This study was focused on the application of ultraviolet light emitting diodes (UV-LED) as an alternate source for the photocatalytic degradation of methylene blue (MB), which was used as a model ...compound. A simple reactor arrangement was made to carry out the photocatalytic degradation of methylene blue dye. The photocatalytic activity of P-25 Degussa TiO2 was evaluated using UV-LED reactor. The decomposition of MB dye in aqueous solution by TiO2 photocatalytic process with the UV-LED was found to be technically feasible. The effects of various parameters such as catalyst loading, initial dye concentration, pH, and addition of H2O2 on decolorization and degradation have been investigated to find the optimum conditions. The complete mineralization of MB dye (3.12 × 10−5 M) was confirmed by chemical oxygen demand analysis. Results demonstrated that the UV-LED/TiO2 process can effectively degrade methylene blue dye with optimum conditions.
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•Developed TOPO-based hydrophobic eutectic solvents for critical metal recovery.•HDES effectively recovered Nd(III) and Dy(III) from 1 M HNO3.•THY:TOPO(1:1) showed highest separation ...factors for Nd/Fe and Dy/Fe.•THY:TOPO(1:1) selectively extracted Nd, Dy, and Pr from NdFeB samples.•TOPO-based HDES offer eco-friendly approach for metal recovery.
Integral to emerging technologies, the escalating demand for NdFeB magnets has emphasized their pivotal role. Yet, natural resource depletion intensifies the supply challenge. Nd (III) and Dy (III), classified as critical metals, compound this concern. Recycling these metals from secondary sources, particularly discarded NdFeB magnets, presents a compelling and sustainable strategy. Here, we employ hydrophobic eutectic solvents (HDES) prepared by mixing an extractant trioctylphosphine oxide (TOPO) with hydrogen bond donors thymol (THY), menthol (MEN), or lauric acid (LAAC) in 1:1 ratio. The prepared HDES was used as an extractant and hydrophobic phase to recover Nd(III) and Dy(III) from magnet leachate, thus avoiding the usage of volatile organic solvents. All three HDES formulations effectively extracted Nd(III) and Dy(III) from 1 M HNO3. Notably, the THY:TOPO (1:1) composition showcased the most remarkable performance in terms of both separation factor and extraction capacity. Stripping Nd(III) and Dy(III) from loaded HDES was achieved using 2 mol/L H2SO4. Through the construction of a McCabe-Thiele diagram and the execution of counter-current experiments, the complete recovery of both Nd(III) and Dy(III) was realized. The THY:TOPO (1:1) also exhibited remarkable extraction capability for all three rare earth elements present Nd(III), Dy(III), and Pr(III) within the original scrap NdFeB magnet leachate at the optimized conditions. This study emphasizes the inherent advantages of formulating eutectic solvents by combining efficient extractants, thereby enhancing the efficiency of metal recovery processes.
Novel ternary nanocomposite photocatalysts based on g-C
/Bi
MoO
/TiO
nanotube were synthesized using simple solid combustion, hydrothermal and wetness impregnation methods. The structural and ...morphological properties of the synthesized photocatalysts were systematically characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy and scanning electron microscopy (SEM). The crystal structure and phase purity of unitary, binary, and ternary photocatalysts were confirmed by XRD analysis. The SEM analysis reveals the tubular morphology of the TiO
nanotube, and the presence of Ti, C, N, Bi, Mo, O, C, and N in the ternary composites was confirmed by EDX analysis. The photocatalytic decolorization efficiency of the ternary composites was evaluated by monitoring the decolorization of reactive black 5 and methylene blue dyes under visible light and direct sunlight irradiation, and these ternary composites were compared with binary composites and unitary photocatalysts in terms of the decolorization efficiency. After five cycles of adsorption and decolorization reactions, it was confirmed that the ternary composite photocatalysts were highly stable and reusable. From the results, we conclude that ternary composites (g-C
/Bi
MoO
/TiO
nanotube) are efficient photocatalysts for the decolorization of dyes.
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