Search

Combining the strong localized surface plasmon resonance (LSPR) of metallic Ag and the chemically reactive Pt co-catalyst, the Ag–Pt bimetallic composite was prepared and then coated on the surface of the exfoliated defective graphitic carbon nitride nanosheets (C 3 N x NS) for plasmon hot electron-mediated photocatalytic H 2 evolution. Under the visible light irradiation, the sample of (1:2) Ag–Pt/C 3 N x NS exhibits the highest activity (1.25 mmol g−1 h−1), which is 35.7 and 1.7 times higher than that of Ag/C 3 N x NS and Pt/C 3 N x NS, respectively. Moreover, the apparent quantum efficiency (AQE) of (1:2) Ag–Pt/C 3 N x NS reaches 3.3% at 420 nm. The boosted photocatalytic capacity may be ascribed to the utilization of the advantages of the LSPR effect of Ag particles and the Schottky barrier between Pt and C 3 N x NS, resulting in more electrons participate in the reduction reaction to boost the photocatalytic H 2 evolution performance. [Display omitted] • Ag–Pt core-shell structure was deposited on the exfoliated defective C 3 N x nanosheets. • The Core Ag shows LSPR effect and the shell Pt acts chemically reactive co-catalyst. • The (1:2) Ag–Pt/C 3 N x NS exhibits the highest H 2 evolution rate (1.25 mmol g−1 h−1). • The AQE of the sample of (1:2) Ag–Pt/C 3 N x NS reaches 3.3% at 420 nm. • The boosted activity was attributed to the LSPR effect and the Schottky barrier. [ABSTRACT FROM AUTHOR]

Copper matrix composite with short carbon fiber(CF)/reduced graphene oxide(rGO) hybrid filler have been fabricated by freeze-drying and spark plasma sintering. Microstructure and tribological properties of as-prepared composites were characterized. The microstructural observation shows that the rGO exhibits both agglomerated and dispersed states, and the uniform CF presents the various space orientations in the Cu matrix. The composite with CF/rGO hybrid filler exhibited the lower friction coefficient (0.32), and whose wear rates decreased respectively by 45.3% and 86.0% in comparison with pure Cu and the composite with rGO filler. The CF/rGO hybrids act as solid lubricant and play the major role in the improved tribological performance. The formation, friction-reducing and anti-wear mechanisms of the composite were discussed. [ABSTRACT FROM AUTHOR]

It is still challenging to fabricate photocatalysts via loaded metal cocatalysts with good dispersion onto the conjugated polymers (CPs). Herein, a donor-acceptor (D–A) structural CP of PyDTDO-3 was employed to host platinum (Pt) nanoparticles (NPs) using N , N ′-dimethylformamide (DMF) as a protectant, stabilizer, and reducing agent, which not only promotes Pt NPs to have excellent dispersion property on the surface of PyDTDO-3 but also endows Pt NPs to maintain metallic Pt0 species. As a result, the PyDTDO-3 loaded with Pt NPs exhibits remarkable hydrogen (H 2) evolution activity with a rate of 39.9 mmol g−1 h−1 under visible light irradiation, and the fair stability of optimal 7% Pt/PyDTDO-3 is expressed in the rate of H 2 generation upon 30 h cycling. Based on density functional theory (DFT) calculations, it has been demonstrated that Pt NPs are selectively loaded onto the acceptor (A) unit of PyDTDO-3 that has the lowest adsorption energies (E ads) and the closest bond lengths between the Pt NPs and PyDTDO-3. Moreover, there are much more electrons filling at the Fermi level (E f), indicating the optimal 7% Pt/PyDTDO-3 with high electroconductivity timely captured and removed the photoinduced electrons and thus realized the space separation efficiency of electron-hole pairs. Overall, our findings offer a rational way to load metal cocatalysts onto CPs with good dispersion for efficient photocatalytic H 2 evolution. [Display omitted] • Well-dispersed Pt NPs are fabricated onto the conjugated D-A type polymers. • DMF was used as a protectant, stabilizer, and reducing agent to obtain metallic Pt0. • Pt (111) plane is selectively loaded onto the acceptor (A) unit of PyDTDO-3. • The photoinduced electrons transfer from D to A unit of PyDTDO-3 and then to Pt NPs. • The optimal 7% Pt/PyDTDO-3 exhibits photocatalytic H 2 rate of 39.9 mmol g−1 h−1. [ABSTRACT FROM AUTHOR]

A novel and rapid strategy has been developed to synthesize tetrahedral Ag 3 PO 4 mesocrystals with the help of surfactant oleic acid. Homogeneous Ag 3 PO 4 tetrahedron with average apex-to-apex length of 1.1 μm could be synthesized under optimized conditions. Oleic acid is considered to be essential for the formation of this homogeneous tetrahedral morphology. The as-prepared tetrahedral Ag 3 PO 4 mesocrystals could be formed through the close-packed assembly of Ag 3 PO 4 nanoparticles, thus the formation of tetrahedral Ag 3 PO 4 mesocrystals is explained by the oriented aggregation mechanism based on time-dependent experiments. Furthermore, the obtained tetrahedral Ag 3 PO 4 mesocrystals exhibit enhanced visible-light photocatalytic degradation of methylene blue (MB) and methyl orange (MO) solutions compared to the reported micro-sized spherical Ag 3 PO 4 particles with high photocatalytic performance. [ABSTRACT FROM AUTHOR]

Using density-functional theory (DFT) calculations within the generalized gradient corrected approximation, the models that nonmetallic impurities X (X = C, N, S, F) substituted for O or Ti sites in anatase TiO 2 were investigated. By calculating the formation energy of X-monodoped TiO 2 with X substituted for O, we suggested that X dopants existed as C 4− , N 3− , S 2− and F − ions, respectively. Meanwhile, the X dopants existed as C 4+ , N 3+ , and S 6+ for X-monodoped (X = C, N, S) TiO 2 with X substituted for Ti. The conclusion of the valence states of nonmetallic impurities X substituted for O or Ti sites in TiO 2 is also supported by the results of optimized cell parameters and the local structures. Furthermore, an effective nonmetallic passivated codoping approach to modify the band edges of TiO 2 is proposed. Based on the first-principle calculations, we suggested that nonmetallic passivated groups such as (S 2− + C 4+ ) and (C 4− + S 6+ ) could reduce the band gap largely and make less perturbation in conduction band minima (CBM), thus lead to an ideal visible-light absorption region without affecting the reducing power. This work provides some new results and is anticipated to give some inspiration and guidance for design visible-light-driven TiO 2 photocatalyst with high efficiency. [ABSTRACT FROM AUTHOR]

Abstract: A series of Ag3PO4 and reduced graphite oxide sheets (RGOs) nanocomposites have been fabricated by a facile chemical precipitation approach in N,N-dimethylformamide (DMF) solvent without any hard/soft templates. The as-prepared Ag3PO4/RGOs composites were characterized by X-ray diffraction pattern (XRD), Fourier transform infrared spectra (FTIR), Raman spectroscopy, field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy (DRS). It is found that the nano-sized Ag3PO4 particles are deposited on the surfaces of RGOs. The Ag3PO4/RGOs nanocomposites exhibit enhanced photocatalytic activity for the photodegradation of organic methyl orange (MO) and methylene blue (MB) under visible light irradiation. The photocatalytic rate of Ag3PO4/2.1wt% RGOs nanocomposite is 3 and 2 times of that of pure Ag3PO4 nanoparticles for the degradation of MO and MB, respectively. Furthermore, the photocatalytic and structural stability of Ag3PO4 is greatly enhanced. It is suggested that RGOs can be used as protective coatings that partially inhibit the photocorrosion of Ag3PO4. Overall, this work could provide a new approach to the improvement not only in the photocatalytic activity but also the stability of photocorrosion catalysts. [Copyright &y& Elsevier]

Abstract: The traditional hydrothermal method for synthesis of H2Ti3O7 nanotubes was modified, and the total hydrothermal reaction time of forming a matured network of H2Ti3O7 nanotubes was successfully decreased by 50%. The effect of hydrothermal reaction time on morphology and photocatalytic activity of H2Ti3O7 nanotubes was investigated and discussed. Various morphologies can be observed in the as-prepared samples with different hydrothermal reaction times. The photocatalytic activity of the as-prepared samples was evaluated for degradation of methyl orange (MO) under simulated solar irradiation. It was found that the sample treated in the hydrothermal condition for 36h with a matured network of H2Ti3O7 nanotubes showed excellent photocatalytic activity. The photocatalytic activity results were discussed in detail. The stronger absorption in the ultraviolet (UV) range, the increasing crystallization of H2Ti3O7 phase, and larger surface area and pore volume contributed to the enhancement of photocatalytic activity of the as-prepared samples. [Copyright &y& Elsevier]

For the construction of metal-semiconductor heterojunctions, the rational regulation of Schottky barriers has an important impact on their photocatalytic activity. Here, we successfully constructed Pd-loaded Al: SrTiO 3 (ASTO) photocatalysts by an in situ strategy, and the photocatalytic hydrogen production performance was conducted under simulated solar light irradiation. The results show that the optimal Pd-ASTO-1.5% photocatalyst exhibits a hydrogen production performance of 1.43 mmol g−1 h−1, which is a 140-fold improvement compared to pure ASTO. Density functional theory (DFT) calculations demonstrate that Pd nanoparticles (NPs) could reduce the energy barrier for hydrogen adsorption. In addition, the optimal Schottky barrier not only accelerates the charge dynamics through the driving force of the Schottky junction but also prevents the flow of electrons trapped by Pd NPs back to ASTO, which greatly improves the interfacial carrier separation efficiency for photocatalytic hydrogen production under simulated solar light irradiation. This work reveals key insights into the construction of Schottky heterojunctions in the field of photocatalytic hydrogen production. [Display omitted] • Pd-loaded Al: SrTiO 3 (ASTO) photocatalysts were prepared by an in situ strategy. • The optimal Schottky barrier accelerates the charge dynamics from ASTO to Pd NPs. • The optimal Pd-ASTO-1.5% photocatalyst exhibited a hydrogen rate of 1.43 mmol g−1 h−1. • DFT calculations showed that Pd NPs reduced the energy barrier for hydrogen adsorption. • The Schottky junction prevents the flow of electrons trapped by Pd NPs back to ASTO. [ABSTRACT FROM AUTHOR]

The silage quality and anaerobic digestion performance of Pennisetum purpereum with molasses-processed wastewater addition were assessed. The silage samples with molasses-processed wastewater addition obtained higher lactic acid concentration of 15.18–23.38 mg/g FM, lower pH value of 3.96–4.45 and lower NH 3 -N content of 0.47–0.64 mg/g FM. No obvious difference was observed in the dominant phyla and genus, but the relative abundance of Lactobacillus reached up to 77.39%, increased by 84% compared to the silage samples without molasses-processed wastewater addition. Combined the silage quality and bacterial community, the decreased in pH value of fresh material caused by molasses-processed wastewater addition was the main reason for improving the silage quality. Meanwhile, the increased in COD concentration is beneficial for improving the specific methane yield and the maximum specific methane yield of 259 ± 5.75 mL/g VS was obtained with adding 20 g/kg molasses-alcoholic wastewater. Molasses-processed wastewater is an alternative additive for silage. [ABSTRACT FROM AUTHOR]

Abstract: The composites of ultrafine TiO2 nanoparticles and graphene sheets (GSs) were prepared via a direct redox reaction. Investigation of morphological features of the composite indicated that nano-sized TiO2 particles were distributed on the surfaces of GSs. The as-prepared TiO2/GSs photocatalysts possessed extended light absorption range, which could be excitated by visible light. These visible-light active photocatalysts were utilized for degradation of Escherichia coli bacteria, and their antibacterial activity against E. coli was much higher than that of pure TiO2 nanoparticles. Overall, a material with high antibacterial activity under ambient visible light illumination was developed, which could be widely used for indoor air disinfection. [Copyright &y& Elsevier]

A hydrothermal method was employed to synthesize the novel 2D/2D BiOCl/H+Ti 2 NbO 7 − heterojunction photocatalysts, showing the improved photocatalytic RhB degradation efficiency. • 2D/2D BiOCl/H+Ti 2 NbO 7 − heterojunction was synthesized by a hydrothermal route. • 2D/2D heterostructure facilitated the efficient charge separation and transfer. • BiOCl/H+Ti 2 NbO 7 − showed the high photoactivity due to heterojunction formation. • The h+ and •O 2 − played a crucial role in RhB photodegradation. To realize highly efficient removal of organic pollutant is a hot spot in environmental and energy science. Herein, we firstly prepared re-stacked H+Ti 2 NbO 7 − nanosheets (HTN) to fabricate the novel two-dimensional (2D)-2D BiOCl/H+Ti 2 NbO 7 − (BHT) heterojunctions by a hydrothermal method. The HTN were well combined with BiOCl nanoplates with an intimate interface to form a heterostructure. The rhodamine B (RhB) molecules were used as a target pollutant to evaluate the photocatalytic performance of samples under visible light. All BHT composites, with an optimal sample of BHT-4, showed the improved photocatalytic activity for degradating RhB compared with the single BiOCl and HTN. The enhanced activity was mainly attributed to the efficient charge separation and transfer, which was resulted from the formation of heterojunction between BiOCl and HTN. The produced active species can be detected by trapping experiments and ESR spectra. It indicated that hole (h+) and superoxide radical (O 2 −) played a crucial role in the photocatalytic RhB degradation, while hydroxyl radical (OH) contributed a little. A possible photodegradation mechanism was also discussed based on the corresponding experimental results. This work provides an insight for preparing 2D/2D heterojunctions with a high photocatalytic activity. [ABSTRACT FROM AUTHOR]

Electricity and water from renewable hydropower plant are used as input for electrolysis unit to generate hydrogen, while CO 2 is captured from 600 MW supercritical coal power plant using post-combustion chemical solvent based technology. The captured CO 2 and H 2 generated through electrolysis are used to synthesize methanol through catalytic thermo-chemical reaction. The methanol synthesis plant is designed, modeled and simulated using commercial software Aspen Plus ® . The reactor is analyzed for two widely adopted kinetic models known as Graaf model and Vanden-Bossche (VB) model to predict the methanol yield and CO 2 conversion. The results show that the methanol reactor based on Graaf kinetic model produced 0.66 tonne of methanol per tonne of CO 2 utilized which is higher than that of the VB kinetic model where 0.6 tonne of methanol is produced per tonne of CO 2 utilized. The economic analysis reveals that 1.2 billion USD annually is required at the present cost of both H 2 production and CO 2 abatement to utilize continuous emission of 3.2 million tonne of CO 2 annually from 600 MW supercritical coal power unit to synthesize methanol. However, sensitivity analysis indicates that methanol production becomes feasible by adopting anyone of the route such as by increasing methanol production rate, by reducing levelised cost of hydrogen production, by reducing CO 2 mitigation cost or by increasing the current market selling price of methanol and oxygen. [ABSTRACT FROM AUTHOR]