Search

Although the physiochemical merits of g-C3N4-based photocatalysts have garnered increasing interest in the fields of energy and environmental science, insufficient layer detachment has created a gap between fundamental research and practical applications. To unlock the intrinsic potential of g-C3N4, a bio-transformation of the ZnMn2O4 ((6)ZM) gel was employed to introduce highly-ordered modulation caused by steric hindrance during melamine pyrolysis. Phytomediated (6)ZM reorganized traditional carbon nitride into crossed C3N4 (CCN) monolayers, simultaneously engineering an auspicious Z-schematic system ((6)ZM/CCN). Phytoconverted (6)ZM retained the crystalline-amorphous configuration for facile charge transfer and provided a large surface area (288 m2 g−1) that was 2.3 times greater than that of thermally prepared g-C3N4 (TCN) monolayers. Additionally, (6)ZM exhibited a quantum confinement-promoted reduction capability and induced bulging on CCN monolayers to fully utilize photons through multilevel light scattering and reflection. Specific sequential two-step calcination of (6)ZM/CCN, furnishing affordable dual Z-schematic VO–(6)ZM/CCN, was specifically developed to introduce a third component into the structure without incurring additional operational cost or complexity. V2O5 (VO) nanoparticles were thermally anchored on (6)ZM/CCN to achieve highly efficient levofloxacin (LFC) detoxification under visible-light irradiation. After optimizing all effective synthesis parameters and experimental variables, VO–(6)ZM/CCN exhibited unsurpassed activity, achieving complete LFC photodegradation (50 mg L−1) within 120 min, which was 10.7, 8.7, and 24.7 times more kinetically efficient than the photodegradations achieved by (6)ZM, TCN, and VO, respectively. The outstanding performance of VO–(6)ZM/CCN was evident through complete mineralization of LFC, excellent decontamination of pharmaceutical wastewater within 300 min, resistance to performance deterioration during successive cycling runs, and the corresponding postcharacterization. The combination of simultaneous Z-scheme formation with photogenic (6)ZM provides a promising strategy to bridge the gap between experimental investigations and industrial applications of g-C3N4. [ABSTRACT FROM AUTHOR]

Multi-shelled configurations of mixed bimetallic oxides, which are well-known candidates for CO2 photoreduction, were prepared via the calcination of rigid spheres of the self-template glycerate-assisted metal–organic structure. However, the fabrication of highly efficient, stable constructions is still a significant challenge. The effectiveness of this strategy is restricted by the questionable stability of the structure, which collapses under harsh calcination conditions. Herein, we focused our attention on manipulating the initial solvothermal reaction, through which MnCo2O4 yolk-in-double-shell hollow spheres (YDSHS-MCO) were engineered via the formation of two sequential yolk-shells, i.e., one during the solvothermal process and the other during the calcination process. To better understand the origin of the superior performance of this structure, its conventional nanoparticle counterpart (NP-MCO) was synthesized, showing that YDSHS-MCO had a much higher photo/electrochemical merits and CO2-to-syngas conversion, which was 8-fold than that of NP-MCO. In addition, optimized ZnMn2O4 nanoparticles (6-ZMO) prepared via the green sol–gel phyto-mediated method were intimately amalgamated on the nanosheet-assembled exterior YDSHS-MCO shell, resulting in the formation of an astounding S-scheme heterojunction ((80)YDSHS-MCO@6-ZMO). The fusion of the small-sized 6-ZMO nanoparticles with the advantages of crystalline-amorphous structure and quantum-confinement-promoted reduction capability introduced efficient reduction centers on the flower-like exterior YDSHS-MCO shell. As anticipated, in the CO2 photoreduction reaction, (80)YDSHS-MCO@6-ZMO demonstrated a superior performance in realizing syngas production of 1401 μmol g−1 h−1 with the CO selectivity of 87.5% in the liquid–solid phase and 2125 μmol cm−2 h−1 in the gas–solid phase without the applying any photosensitizer/sacrificial agents. Regarding its stability, after a long-term experiment and time-equivalent successive cycling reactions in both systems (gas–/liquid–solid phase), its post-characterization and photocatalytic performance demonstrated the successful resilience engineering. The unique architecture of the stable multi-shell amalgamated with the rational configuration of an S-scheme encompasses a facile, low-cost structure that surpasses its counterparts in various domains. [ABSTRACT FROM AUTHOR]

Air pollution is known as one of the most important causes of death in the whole world. Therefore, pollution reduction to achieve clean air was noticed by everyone. This way, using nanotechnology to control air and monitor is a novel approach. This paper investigates the effect of the number of graphene nano-pores on the SiO 2 separation from the H 2 O vapour in the presence of an external electric field with the magnitude of 0.01 V/Å using the molecular dynamics (MD) method. The electric field affects the charged particles and causes disturbance in the structure. It also prevents SiO 2 nanoparticles from passing through the graphene nanosheet. Also, the presence of carbon nanosheets acts as a membrane and affects the diffusion of water in the nanostructure. So, the results show that in the presence of a nano-pore, the number of H 2 O molecules reaches to 496 and 568 in reservoirs 2 and 3. Also, the number of SiO 2 nanoparticles reaches 10 and 4 in reservoirs 2 and 3. This shows that in reservoirs 2 and 3, about 80% and 60% of the SiO 2 nanoparticles are separated. As mentioned before, the electric field prevents the passage of SiO 2 nanoparticles through the graphene nanosheet. As the number of graphene nano-pores increases by 2, 3, 4, and 5, the number of passing water molecules increases. Considering that the number of graphene nano-pores has increased and the movement path of particles has increased, the number of passing particles almost increases. However, the electric field prevents the passage of SiO 2 nanoparticles. According to the results, the suggested setup can be employed for designing highly efficient nanostructured membranes for air purification and monitoring. [Display omitted] [ABSTRACT FROM AUTHOR]

Waste-derived materials obtained from the recovery and recycling of electronic waste (e-waste) such as batteries and printed circuit boards have attracted enormous attention from academia and industry in recent years, especially due to their eco-friendly nature and the massive increment in e-waste due to technological development. Several investigations in the literature have covered the advances achieved so far. Meanwhile, photocatalytic applications are especially of interest since they maintain mutual benefits and can be used for H2 production from solar water splitting based on semiconductor processing as a proper environmentally friendly technique for solar energy conversion. In addition, they can be utilized to degrade a variety of organic and non-organic contaminations. Nonetheless, to the best of the authors' knowledge, there has not been any comprehensive review that has specifically been focused on e-waste-derived photocatalytic materials. In this regard, the present work is dedicated to thoroughly discussing the related mechanisms, strategies, and methods, as well as the various possible photocatalysts synthesized from e-wastes with some critiques in this field. This brief overview can introduce modern technologies and promising possibilities for e-waste valorization, photocatalytic processes, and new photocatalytic degradation methods of eco-friendly nature. This paper discusses various e-waste-obtained photocatalytic materials, synthesis procedures, and applications, as well as several types of e-waste, derived materials such as TiO2, ZnO, indium tin oxide, and a variety of sulfide- and ferrite-based photocatalytic materials. [ABSTRACT FROM AUTHOR]

Today, as a result of the advancement of technology and increasing environmental problems, the need for clean energy has considerably increased. In this regard, hydrogen, which is a clean and sustainable energy carrier with high energy density, is among the well-regarded and effective means to deliver and store energy, and can also be used for environmental remediation purposes. Renewable hydrogen energy carriers can successfully substitute fossil fuels and decrease carbon dioxide (CO2) emissions and reduce the rate of global warming. Hydrogen generation from sustainable solar energy and water sources is an environmentally friendly resolution for growing global energy demands. Among various solar hydrogen production routes, semiconductor-based photocatalysis seems a promising scheme that is mainly performed using two kinds of homogeneous and heterogeneous methods, of which the latter is more advantageous. During semiconductor-based heterogeneous photocatalysis, a solid material is stimulated by exposure to light and generates an electron–hole pair that subsequently takes part in redox reactions leading to hydrogen production. This review paper tries to thoroughly introduce and discuss various semiconductor-based photocatalysis processes for environmental remediation with a specific focus on heterojunction semiconductors with the hope that it will pave the way for new designs with higher performance to protect the environment. [ABSTRACT FROM AUTHOR]

Often the choice of semiconductor material for light‐chemical energy conversion in solar cell technology is TiO2 polymorphs. However, quantum‐mechanical phenomena of electron self‐trapping (polaron) in these polar semiconductors present a challenge to optimize their performance for absorption of solar radiation. The electron trapped in the defect site of the lattice may suppress the recombination of charge carriers and improve the efficiency of light‐chemical energy conversion. Therefore, it is crucial to study polarons in transition metal oxides and semiconductors using first‐principles methods to elucidate the nature of charge carriers and trapping sites for ameliorating the performance of energy conversion. In this work, a comprehensive review is presented using selected literature of polaron studies in TiO2 from first‐principles methods. Overview of the Landau–Pekar model to the recent development of ab initio theory of polaron is presented. The popular DFT+U approach and hybrid functional method are discussed to show the general way of studying polaron using ab initio methods. Introduction of electron‐phonon interaction and the ab initio theory of polaron are briefly presented Therefore, this review presents the development of first‐principles methods from Landau theory to the state‐of‐the‐art to study polarons using TiO2 as the toy model. Finally, conclusions and future perspectives are outlined. [ABSTRACT FROM AUTHOR]

Ti-XAl-2Fe-3Cu (X = 2.7, 4 wt%) alloys with a high tensile yield strength of up to 1150 MPa were synthesized using powder compact extrusion from blended TiH 2 and elemental powders. The microstructures and mechanical properties of the extruded rods without and with a homogenization heat treatment at 1000 °C for 1 h followed by furnace cooling were investigated. It was found that the Al content and heat treatment had significant effects on the microstructures and mechanical properties. With increasing the Al content from 2.7 to 4 wt%, the average lamellar colony size and lamellar thickness of the as-extruded Ti-XAl-2Fe-3Cu alloy decreased from 442.4 to 224.1 µm and 6.7–5.2 µm respectively. The heat treatment increased the lamellar thickness as well as the level of partitioning of Fe and Cu between α and β phases. As a result of the microstructural changes, increasing Al from 2.7 to 4 wt% caused a slight increase in the strength of Ti-XAl-2Fe-3Cu alloys without changing the ductility, while the heat treatment slightly reduced the strength of the alloys, but clearly increased their tensile ductility. The correlation between microstructures and mechanical properties is discussed. [ABSTRACT FROM AUTHOR]

• Novel Bi 2 WO 6 -ZnBi 2 O 4 heterojunction was prepared by sonochemical assisted hydrothermal method. • Sonochemical pretreatment caused spherical to flake-like morphology evolution. • The optimal Bi 2 WO 6 -20ZnBi 2 O 4 revealed good stability (4% loss) after 5 cycling runs. • Direct Z-scheme mechanism was proposed for the enhanced photodegradation of MG. • Bi 2 WO 6 -ZnBi 2 O 4 can efficiently remove both MG dye and colorless 2,4-DCP contaminants. In this work, novel Bi 2 WO 6 -ZnBi 2 O 4 p-n heterojunction was successfully synthesized through combination of sonochemical and hydrothermal procedures. The results revealed that the sonochemically prepared nanocomposites had spherical shape with amorphous structure which became crystalline particles with flak-like morphology after hydrothermal treatment. Bi 2 WO 6 -ZnBi 2 O 4 nanocomposite with 20 wt% ZnBi 2 O 4 content demonstrated the highest photocatalytic performance compared to the pure Bi 2 WO 6 and ZnBi 2 O 4 samples toward the degradation of Malachite Green (MG). This finding is associated with the efficient separation of photo-generated electron/hole pairs due to the formation of interfacial charge transfer between Bi 2 WO 6 and ZnBi 2 O 4. However, further ZnBi 2 O 4 loading had no significant effect on the enhancement of photocatalytic activity of nanocomposite samples owing to the shielding effect of ZnBi 2 O 4 against incident light. The obtained results were further verified by optical and photocurrent density measurements. Based on the obtained results from active species trapping experiments, electron spin resonance and Mott-Schottky calculations, the Z-scheme charge transfer pathway was proposed as the predominant mechanism for the photocatalytic reactions. Also, the photocatalytic degradation of 2,4-dichlorophenol, as a colorless model pollutant, was conducted on optimal composite sample to study the possible contribution of MG dye sensitization mechanism in the enhancement of photocatalytic efficiency. [ABSTRACT FROM AUTHOR]

• The Ti-2.7Al-2Fe-3Cu alloy depicts a full α/β lamellar structure, while the Ti-4Al-2Fe-3Cu alloy depicts an α/β lamellar structure together with continuous grain boundary α layers. Since Al is an α phase stabilizer, increasing Al content increases the amount of α phase in Ti-XAl-2Fe-3Cu alloys. • Increasing the Al content in Ti-XAl-2Fe-3Cu alloy from 2.7 to 4wt% increases the hardness, compressive strength and biocorrosion resistance of the alloy. • Ti-XAl-2Fe-3Cu alloys show a significantly higher polarization resistance and double layer capacitance because of the enveloping effect owing to the existence of a compact oxide layer. Ti-XAl-2Fe-3Cu (wt%) (X = 2.7,4) alloys were fabricated by extrusion of compacts of TiH 2 /Al/Fe/Cu powder blends. The microstructure and compressive and biocorrosion properties of the as-extruded rods were studied and compared to those of commercial pure (CP) Ti fabricated by extrusion of a TiH 2 powder compact under the same condition. The results show that the Ti-XAl-2Fe-3Cu alloy samples exhibit a significantly higher hardness and compressive yield strength than the CP Ti sample, and with increasing the Al content from 2.7 to 4 wt%, the compressive yield strength of the alloy increases from 1315 to 1422 MPa. The Ti-XAl-2Fe-3Cu alloy samples possess a better biocorrosion resistance than CP Ti, and the polarization resistance of the alloy increases with increasing Al content due to the reduced diffusion rate of corrosive ions through the surface oxide layers. Furthermore, with increasing the immersion time, the polarization resistance increases, and the double layer capacitance decreases. Overall the alloys show significantly better compressive strength and biocorrosion resistance than CP Ti, suggesting that they are more favorable than CP Ti for biomedical applications. [ABSTRACT FROM AUTHOR]

Upgrading of biomass wastes to value-added materials has been incessantly pursued worldwide with diverse applications, especially deploying photocatalytic composites encompassing metal oxides with acidic and carbon compounds. Herein, the fabrication of a morphologically unique acidic catalyst encompassing a two-dimensional (2D) TiO 2 /g-C 3 N 4 heterojunction feature is described for the generation of 5-hydroxymethylfurfural (5-HMF), which exploits the acidic/ionic liquid (IL) bifunctional photocatalysis under visible light. The structural integrity of the synthesized TiO 2 /g-C 3 N 4 /SO 3 H(IL) was corroborated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy-energy-dispersive spectroscopy (EDX-EDS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), UV-vis, Tauc plots, transmission electron microscopy (TEM), and Brunauer-Emmett-Teller-Barrett-Joyner-Halenda (BET-BJH) analyses. Keeping environmental impact in mind, there are compelling advantages in the development of bio-derived pathways to access ILs from natural renewable resources. The outcomes of environmental assessments have revealed that the incorporation of TiO 2 in g-C 3 N 4 and ClSO 3 H can reduce the probability of recombination due to ionic charges present, therefore enhancing the photocatalytic activity via the transformation of cellulose and glucose to produce 5-HMF in higher yields, with the optimum conditions being reaction in water under a blue light-emitting diode (LED), at 100 °C, for 1-1.5 h. The main advantages of this production method include minimum number of synthetic steps as well as ample availability of and easy access to primary ingredients. While a significant volume of 5-HMF was produced under blue light-emitting diode (LED) radiation, the selectivity was drastically reduced in the dark. The salient attributes of the catalyst comprise stability in air, robustness, reusability, and its overall superior activity that is devoid of hazardous additives or agents. This inimitable method has uncovered a newer strategy for enhancing the photocatalytic attributes of deployed semiconducting materials for numerous photocatalytic functions while adhering to the tenets of environmental friendliness.

Surface modification for templated synthesis is crucial to achieving three-dimensional (3D) architectured materials for catalysis, photonics, energy storage, etc. However, the existing facile and versatile modification methods (e.g. with dopamine and catechol) generate modification layers that are unstable in harsh environments. These methods are thus unsuitable for electrical applications. Here we report that Ce4+ can act as an effective surface modification reagent for a broad range of substrates (chitinous butterfly wings, carbon paper, nickel foam, and polyethylene terephthalate planks) with various structural features owing to its strong oxidizing ability and Lewis acid nature. The modification yields discrete CeO2 seed layers on substrate surfaces in ca. 0.25-2 h, important for the subsequent conformal growth of CeO2 nanoparticles, Ni(OH)2 nanowires, FeOOH nanosheets, and WO3 nanosheets into 3D architectured materials. The conformally synthesized FeOOH on nickel foam (NF) yields an overpotential of 241 mV at 10 mA cm-1 for an oxygen evolution reaction. This value is comparable to a typical catalyst Ni(Fe)OOH-NF for which the Ni/Fe ratio must be well-optimized. This facile and versatile strategy might have broad applications in the conformal fabrication and application of 3D architectured materials, especially when applied in electrical applications of architectured materials (e.g. Li-ion battery).