Search

Photocatalytic ammonia synthesis from waste nitrate provides a green strategy for water treatment, which holds great significance for the global water cycle. However, there is still a lack of highly efficient catalysts to meet the high conversion and selectivity. Herein, a nanostructured photocatalyst was prepared by assembling perovskite (LaFeO3) on hydrothermal carbonation carbon (HTCC) via a facile microwave hydrothermal method, which was employed to reduce nitrate to ammonia. The two-dimensional HTCC nanosheet had a large specific surface area and abundant surface functional groups, and Fe/La salt participated in the surface modification of HTCC, promoting the exposure of oxygen-containing functional groups and aromatic structure, which was favorable for the nitrate adsorption. Furthermore, the HTCC constructed a p–n heterojunction with LaFeO3, which improved the photocatalytic activity attributed to the fast separation of photogenerated electron holes. At the optimized mass ratios of pomegranate peel to Fe/La salt, the LaFeO3/HTCC photocatalyst achieved a highest nitrate removal of 94.6% and an ammonia selectivity of 88.7% under visible light irradiation. This work provides the approach for the photocatalytic synthesis of ammonia from residual nitrate pollutants. [ABSTRACT FROM AUTHOR]

The "trinitrogen" [ammonia nitrogen (NH4+ − N), nitrate nitrogen (NO3− − N), and nitrite nitrogen (NO2− − N)] from industrial or domestic wastewater can lead to eutrophication of water bodies. When ammonia nitrogen is converted into nitrate nitrogen, it will cause high nitrogen oxygen demand, which will also lead to hyperammonemia. High nitrite content in water bodies will increase the risk of human cancer. In this paper, Fe-Ce bimetallic-doped composites (Fe-Ce/SiO2 and Fe-Ce-SiO2/TiO2) were synthesized using SiO2 aerogel as a carrier for the adsorption and degradation of "three nitrogen." SiO2/TiO2 was prepared by dipping method, and Fe and Ce bimetals were loaded on the surface of SiO2/TiO2 material, and the effect of photo-Fenton oxidation on the degradation rate of three nitrogen under different materials was explored. The results showed that when the dosage of catalyst was 0.01 g, pH value was 11.0, and the concentration of H2O2 was 80 mmol/L, the photocatalytic efficiency was the best, and the degradation efficiency of three nitrogen remained above 70%. [ABSTRACT FROM AUTHOR]

Using natural mineral to realize photocatalytic reduction of CO 2 is promising but remains a great challenge. Herein MoO 3-x quantum dots (QDs) immobilized on acid modified palygorskite (H-Pal) nanocomposite was prepared as powder photocatalyst for CO 2 conversion. The effect of various mass fractions of MoO 3-x on CO 2 reduction was investigated. Results reveal that the 30% MoO 3-x /H-Pal demonstrates remarkable CO 2 photoreduction property with a CH 3 OH yield rate of about 6.2 μmol·g−1·h−1 under full spectrum irradiation. The MoO 3−x QDs possess high localized surface plasmon resonance (LSPR) effect induced by oxygen vacancy (Ov) not only enables the efficient capture of NIR photons, but also build S-scheme heterostructure with H-Pal mediated by Ov enhancing the separation of charge carriers as well as preserving high redox potential. In addition Ov act as active sites promoting the adsorption and activation of CO 2. This work may provide a cost-effective strategy for the practical application of artificial photosynthesis. [Display omitted] • MoO 3-x QDs/Palygorskite photocatalyst was fabricated. • Optimal MoO 3-x QDs led to form S-scheme heterostructure. • LSPR effect enables the efficient capture of NIR photons. • Charge separation and redox ability was enhanced. • Outstanding CO 2 reduction achieved under solar light. [ABSTRACT FROM AUTHOR]

Novel V doped BiPO 4 /attapulgite nanocomposites (BiP 1 − x V x O 4 /ATP) were prepared via microwave-hydrothermal method. XRD, TEM, FT-IR, UV–Vis and XPS were employed to characterize the powder products. It was found that the ATP nanofibers favored the controllable assembly of Bi-based nanoparticles on its surface. Adequate V doping generated BiP 1 − x V x O 4 solid solution in conjunction with co-precipitated BiVO 4 , which formed dumbbell-shaped heterostructure of BiP 1 − x V x O 4 /BiVO 4 as also proved by DFT calculations. The molar fraction of V doping played a significant role in the photocatalytic desulfurization. Results showed that the desulfurization rate achieved 90% under solar light irradiation when x was optimized to be 0.6, due to the reason that in addition to the contribution of ATP fibers with adsorption capacity, the staggered heterostructure BiP 1 − x V x O 4 /BiVO 4 not only promoted the solar light harvesting, but also accelerated the migration of charges, thus improved the desulfurization efficiency of the powders. [ABSTRACT FROM AUTHOR]

CeO 2 /attapulgite (ATP)/g-C 3 N 4 nanocomposite materials were prepared by a facile electrostatic-induced self-assembly method. In this ternary structure, ATP skeleton effectively increases the surface area with abundant adsorption sites and prevents g-C 3 N 4 from restacking while the g-C 3 N 4 extends the adsorption edge of the CeO 2 to visible region and facilitates the separation of electrons and holes via the formation of CeO 2 /g-C 3 N 4 heterojunctions. The mass ratio of CeO 2 and g-C 3 N 4 in the CeO 2 /ATP/g-C 3 N 4 nanocomposites was adjusted so that r = M Ce /(M Ce + M g ) was 0.1, 0.3, 0.5, 0.7, 0.9, respectively. Benefiting from the synergetic effect, 98% of dibenzothiophene (DBT) in the model oil was converted within 3 h by using CeO 2 /ATP/g-C 3 N 4 ( r = 0.5) as the photocatalyst under visible light irradiation. Moreover, the CeO 2 /ATP/g-C 3 N 4 composite had no detectable loss of photocatalytic activity after eight cycles, indicating excellent recyclability as was also supported by in-situ TEM heating measurement. The OH radicals and holes are responsible for the photocatalytic oxidation as elucidated by the test of electron spin resonance (ESR) and gas chromatography–mass spectrometry (GC–MS). Reaction kinetics and influencing parameters, including catalyst dosage and H 2 O 2 amount, on the desulfurization were further investigated. [ABSTRACT FROM AUTHOR]

A novel Bi 2 W 1−x Mo x O 6 /Montmorillonite (MMT) nanocomposite was prepared by one-pot hydrothermal method. XRD, TEM, Raman, UV–vis, FT-IR, PL and XPS were employed to characterize the nanocomposites. The photocatalytic desulfurization properties of Bi 2 W 1−x Mo x O 6 /MMT nanocomposites were performed by oxidizing dibenzothiophene (DBT) in the model oil under visible light irradiation. Results indicate that the molar fraction of Mo doping has critical impact on the desulfurization rate. Adequate Mo doping may form well-defined “solid solution/co-precipitation” heterostructure of Bi 2 W 1−x Mo x O 6 /Bi 2 MoO 6 , which enhances the visible light absorption efficiency and promotes the separation rate of photogenerated electron-hole pairs, thus leads to the improved photocatalytic desulfurization performance. The desulfurization rate of the model oil can reach 95% when the molar fraction x is 0.7 under visible light irradiation for 3 h. [ABSTRACT FROM AUTHOR]

Novel attapulgite(ATP)-CeO 2 /MoS 2 ternary nanocomposites were synthesized by microwave assisted assembly method. The structures of the nanocomposites were characterized by XRD, FT-IR, UV–vis, XPS and in situ TEM. The photocatalytic activities of ATP-CeO 2 /MoS 2 composites were investigated by degradating dibenzothiophene (DBT) in gasoline under visible light irradiation. The effect of the mass ratio of CeO 2 to MoS 2 on photocatalytic activity was investigated. The results indicate that the three-dimensional network structure is firmly constructed by ATP skeleton, CeO 2 particles and MoS 2 nanosheet which effectively increase the surface area of the composites and promote the separation of electrons and holes by resulting electronic transmission channels of multi-channel in space. The degradation rate of DBT can reach 95% under 3 h irradiation when the mass ratio of CeO 2 /MoS 2 is 4/10. A plausible mechanism for the photocatalytic oxidative desulfurization of this nanocomposite is put forward. [ABSTRACT FROM AUTHOR]

Photocatalysis has great potential on converting lignin biomass to value-added chemicals. Herein, dendritic-like CeVO 4 in situ grew on the phosphoric acid-activated palygorskite (P-Pal) nanorod surface and 5% incorporation of Gd3+ ions achieved the strongest up-conversion property, which converted near infrared (NIR) light into UV and visible light boosting the absorption range of solar energy. Under optimized 6 h sunlight irradiation, the highest conversion rate of sodium lignosulfonate (SLS) can reach 73.2%, and the vanillin yield can reach 4.5 mg/g SLS. Gd3+: CeVO 4 and P-Pal formed well-defined Z-scheme heterojunction which retained strong redox ability of charge carriers, and·O 2 - acted as the main reactive species for the photocatalytic conversion of SLS to valuable products. Notably, abundant Lewis acid sites and Brønsted acid sites induced by phosphoric acid acted as active sites boosting the cleavage of C-C bonds in SLS. Present work offers an alternative for mineral-based catalysts toward photocatalytic conversion of biomass. [Display omitted] • Gd3+: CeVO 4 /P-Pal nanocomposite synthesized by microwave hydrothermal method. • Gd3+ incorporation achieved strong up-conversion enhancing the utilization of solar energy. • Z-scheme heterojunction retained strong redox ability to generate·O 2 - radicals. • Abundant Lewis and Brønsted acid sites boosted the cleavage of C-C bonds. • Remarkable sodium lignosulfonate conversion and vanillin selectivity achieved. [ABSTRACT FROM AUTHOR]

• Cost-effective hierarchical photocatalyst developed by 1-D natural mineral. • Incorporation of Fe into the Pal framework reduces the band gap. • In situ precipitated Fe 2 O 3 enhances the light absorption and active sites. • Z-scheme Fe 2 O 3 /Fe-Pal heterojunction retains high charge potential for N 2 reduction. Achieving sustainable ammonia synthesis strategies to replace traditional Haber-Bosch process remains a significant challenge; however, photo-driven catalysis system based on natural nano-minerals promises a great potential to meet the challenge. In our work, an acid-treated natural one-dimensional clay palygorskite (Pal) is substituted with iron ion to realize lattice reconstruction via a microwave-hydrothermal process. The modified Pal with Fe substitution (Fe-Pal) has the original crystal structure with a narrowed band gap. As the mass ratio of Fe is beyond 30 wt%, extra Fe 2 O 3 precipitates on the Pal surface and the nanocomposite resembles a dendritic heterostructure, which effectively enhances visible light absorption and exposes abundant active sites for synergistic adsorption and photo-activation of nitrogen. The 60 wt% Fe-Pal nanocomposite exhibits a remarkable photocatalytic fixation capability for nitrogen under the visible light. Density function theory calculation is employed to help elucidate the photocatalytic mechanism. Our findings potentially provide a green and cost-effective way to synthase nitrogen. [ABSTRACT FROM AUTHOR]