Effectively H2 generation over CdS/KTa0.75Nb0.25O3 composite via water splitting

CuS/KTa0.75Nb0.25O3 nanocomposite utilizing solar and mechanical energy for catalytic N2 fixation

This work synthesized a novel CuS/KTa_0.75Nb_0.25O₃ (KTN) heterojunction composite and firstly applied it in photocatalytic and piezocatalytic reduction of N₂ to NH₃. XRD, Raman, XPS, SEM, and TEM analyses indicate that CuS nanoparticles closely adhered to the surface of KTN nanorods, which facilitates the migration of electrons between the two semiconductors. Mott-Schottky and valence band XPS analysis shows that KNbO₃ shows a higher conduction band than CuS, indicating that CuS mainly acts as electron trappers to capture the photogenerated electrons from KTN. Because of the great enhanced spatial separation of photogenerated charge carriers, the CuS/KTN presents much higher performance than pure KNT, which is further confirmed by ¹H NMR analysis of the reaction solution. An interesting finding is that synthesized CuS/KTN not only performs well under light irradiation but also can work in an ultrasonic bath, indicating its great potential in photo/piezocatalytic conversion of N₂ to NH₃. The optimal 10 %CuS/KTN shows an NH₃ production rate of 36.2 μmol L^-1 g^-1 h^-1 under ultrasonic vibration, which reaches 7.4 times that of KTN. The electrons generated by KTN through the piezoelectric effect can be captured by CuS, which endows the electrons a longer life to participate in the reaction, thereby improving the catalytic reaction performance.

Fabrication of ternary AgBr/BiPO4/g-C3N4 heterostructure with dual Z-scheme and its visible light photocatalytic activity for Reactive Blue 19

A plasmonic photocatalyst of AgBr/BiPO₄/g-C₃N₄ was prepared. X-ray powder diffraction, Scanning electron microscope, Transmission electron microscopy, Fourier infrared spectroscopy, Ultraviolet Visible diffuse reflectance spectroscopy and photoluminescence emission spectra have been employed to determine the structure, morphology and optical property of the as-prepared AgBr/BiPO₄/g-C₃N₄ composite and analysis the reasons for improving photocatalytic efficiency. The optimal doping ratio of AgBr was 10 wt% by degrading 20 mg/L of Reactive Blue 19 (RB19) under visible light (λ > 420 nm), and 10 wt%AgBr/BiPO₄/g-C₃N₄ degraded 20 mg/L of RB19 to 2.59% at 40 min, which is ascribed to synergistic effects at the interface of AgBr, BiPO₄ and g-C₃N₄. The effect of catalyst dosage, initial concentration and initial pH of RB19 solution on photocatalytic efficiency was investigated. Four cycles of experiments were conducted. Finally, through the trapping experiment, we found that the main active factor for degrading RB19 in the photocatalytic process is O₂^-. The possible photocatalytic mechanism of AgBr/BiPO₄/g-C₃N₄ was discussed in connection with the synergistic effect of Ag and active substances at the AgBr/BiPO₄/g-C₃N₄ interface.

Biomimetic design and synthesis of visible-light-driven g-C3N4 nanotube @polydopamine/NiCo-layered double hydroxides composite photocatalysts for improved photocatalytic hydrogen evolution activity

In the practical process of photocatalytic H₂ evolution, optimizing the ability of light absorption and charge spatial separation is the top priority for improving the photocatalytic performance. In this study, we elaborately engineer neoteric g-C₃N₄ nanotube@polydopamine(pDA)/NiCo-LDH (LPC) composite photocatalyst by combining hydrothermal and calcination method. In the LPC composite system, the one-dimensional (1D) g-C₃N₄ nanotubes with larger specific surface area can afford more active sites and conduce to shorten the charge migration distance, as well as the high-speed mass transfer in the nanotube can accelerate the reaction course. The g-C₃N₄/NiCo-LDH type-II heterojunction can efficaciously stimulate the spatial separation of photo-produced charge. In addition, pDA as heterojunction metal-free interface mediums can provide multiple action (π-π* electron delocalization effect, adhesive action and photosensitization). The optimized LPC nanocomposite displays about 3.3-fold high photoactivity for H₂ evolution compared with the g-C₃N₄ nanotube under solar light irradiation. In addition, the cycle experiment result shows that the LPC composite photocatalyst possesses superior stability and recyclability. The resultant g-C₃N₄@pDA/NiCo-LDH composite photocatalyst displays the potential practical application in the field of energy conversion.

Mesocrystalline Ta3N5 superstructures with long-lived charges for improved visible light photocatalytic hydrogen production

Highly ordered mesocrystalline semiconductors often indicate tremendous prospects in the clean energy production and environmental photocatalysis mainly because of their unique superstructure for efficient charge transport pathways and long-lived charges. Here, superstructure Ta₃N₅ mesocrystals with the high-energy surface {2 0 0} planes exposed were the first time to be successfully fabricated by topological transformation of Ta₂O₅ mesocrystals. The prepared Ta₃N₅ mesocrystals showed enhanced visible-light photocatalytic hydrogen production activity of 98.67 μmol g^-1 for 180 min irradiation, which was approximately 5.28 times that of comm-Ta₃N₅ prepared with commercial Ta₂O₅ as the starting material, mainly due to the formation of long-distance electron conduction pathways and long-lived charges. The detailed electronic band structures of the prepared Ta₃N₅ mesocrystals were also investigated by electrochemical method. Finally, possible visible-light photocatalytic mechanisms of Ta₃N₅ mesocrystals for enhanced hydrogen production was also proposed in detail. Current work also indicates that tantalum-based mesocrystals show great potential to enhance the charge separation for efficient photocatalytic water splitting.

The influence of the sacrificial agent nature on transformations of the Zn(OH)2/Cd0.3Zn0.7S photocatalyst during hydrogen production under visible light

Photocatalysts based on zinc hydroxide and a solid solution of CdS and ZnS were prepared via the precipitation method and used for photocatalytic hydrogen production from aqueous solutions of inorganic (Na₂S/Na₂SO₃) and organic (ethanol) sacrificial agents. The photocatalysts were tested in cyclic experiments for hydrogen evolution and studied using X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy, high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS) techniques. Different transformations of the β-Zn(OH)₂ co-catalyst were observed in the presence of inorganic and organic sacrificial agents; namely, ZnS was formed in Na₂S/Na₂SO₃ solution, whereas the formation of ε-Zn(OH)₂ was detected in solution with ethanol. The composite Zn(OH)₂/Cd_1−xZn_xS photocatalysts have great potential in various photocatalysis processes (e.g., hydrogen production, CO₂ reduction, and the oxidation of organic contaminants) under visible light.

The nature of the sacrificial agent affects the transformations of a Zn(OH)₂ co-catalyst during photocatalytic hydrogen production.

Porous lantern-like MFI zeolites composed of 2D nanosheets for highly efficient visible light-driven photocatalysis

Porous lantern-like MFI zeolites composed of 2D nanosheets were fabricated for highly efficient visible light-driven photocatalysis.

Dual modification of TiO2 nanorod arrays with SiW11Co and Ag nanoparticles for enhanced photocatalytic activity under simulated sunlight

Well-organized TiO₂ nanorod arrays (TNRs) have increasingly attracted our attention in recent years due to their excellent photocatalytic properties. However, it is of great importance to prepare more efficient photocatalysts using a facile method towards their more widespread use. In this work, K₆SiW₁₁O₃₉Co(ii)(H₂O) (SiW₁₁Co) and Ag nanoparticles were introduced into TNRs using spin-coating and chemical bath deposition methods. It was found that TNRs/SiW₁₁Co/Ag composite films with an active area of only 1 cm² exhibit highly efficient and sustainable properties for the photodegradation of NO₂ and display a significant enhancement compared with P₂₅ and pure TNRs. Photocatalytic measurements demonstrated that both SiW₁₁Co and Ag synergistically improve the light absorption and charge separation efficiency, thus obtaining the most efficient photocatalytic performance. In addition, the probable photocatalytic mechanism and the dominating active species for NO₂ photodegradation were also proposed, in order to testify the effectively enhanced photocatalytic ability of the TNRs/SiW₁₁Co/Ag composite. Hence, the design of these polyoxometalate and metal particle co-modified TNRs may provide a new tactic for developing promising materials for photocatalytic degradation.

Fabrication of nanostructured NiO/WO3with graphitic carbon nitride for visible light driven photocatalytic hydroxylation of benzene and metronidazole degradation

Fabrication of a novel NiO/WO₃nanohybrid modified graphitic carbon nitride nanosheets with enhanced photocatalytic activity towards photocatalytic hydroxylation of benzene and degradation of a pharmaceutical waste metronidazole.

Fabrication of a Z-scheme AgBr/Bi4O5Br2 nanocomposite and its high efficiency in photocatalytic N2 fixation and dye degradation

Z-scheme AgBr/Bi₄O₅Br₂ nanocomposite was synthesized via a simple ion-exchange method and firstly applied in photocatalytic N₂ fixation under simulated sunlight.