Boosting visible-light-driven photocatalytic performance of waxberry-like CeO<inf>2</inf> by samarium doping and silver QDs anchoring

In this work, waxberry-like CeO2 photocatalyst (denoted ASC) with prominent visible-light-driven photocatalytic performances for multi-model reactions was achieved by Sm doping and Ag quantum dots (QDs) anchoring. For instance, the as-fabricated ASC acquired 7.08-times and 6.83-times higher activities for CH3CHO removal and H2 production than those of pure CeO2 counterpart, respectively. The concentration of oxygen vacancies (Ov) in CeO2 is distinctly increased by Sm doping, resulting in a narrower bandgap of the Sm-doped CeO2 (SC). Under visible light irradiation, the Ov caused by doping can capture the photo-excited electrons and construct a doping-related transition state between the conduction band (CB) and the valence band (VB), which can effectively limit the recombination of photo-excited electrons and holes. These captured electrons further fleetly transfer to the co-catalytic sites of anchored Ag QDs, strengthening the absorption utilization for visible-light synchronously. The migration of charge carriers and proposed mechanisms were well elaborated by transient photovoltage (TPV), surface photovoltage (SPV) and density functional theory (DFT) calculation. It is hoped our work in this paper could provide potential and meaningful strategies for the design of noble metal quantum dots modified metal oxide semiconductors and facilitate their applications in other photocatalytic fields effectively

Preparation of stable magnetic nanofluids containing Fe3O4@PPy nanoparticles by a novel one-pot route

Stable magnetic nanofluids containing Fe3O4@Polypyrrole (PPy) nanoparticles (NPs) were prepared by using a facile and novel method, in which one-pot route was used. FeCl3·6H2O was applied as the iron source, and the oxidizing agent to produce PPy. Trisodium citrate (Na3cit) was used as the reducing reagent to form Fe3O4 NPs. The as-prepared nanofluid can keep long-term stability. The Fe3O4@PPy NPs can still keep dispersing well after the nanofluid has been standing for 1 month and no sedimentation is found. The polymerization reaction of the pyrrole monomers took place with Fe3+ ions as the initiator, in which these Fe3+ ions remained in the solution adsorbed on the surface of the Fe3O4 NPs. Thus, the core-shell NPs of Fe3O4@PPy were obtained. The particle size of the as-prepared Fe3O4@PPy can be easily controlled from 7 to 30 nm by the polymerization reaction of the pyrrole monomers. The steric stabilization and weight of the NPs affect the stability of the nanofluids. The as-prepared Fe3O4@PPy NPs exhibit superparamagnetic behavior

thermodynamicpropertiesoftheazeotropicmixtureofacetonecyclohexaneandmethanol

Molar heat capacities of the pure samples of acetone, methanol and the azeotropic mixture composed of acetone, cyclohexane and methanol were measured by an adiabatic calorimeter from 78 to 320 K. The solid-solid and solid-liquid phase transitions of the pure samples and the mixture were determined based on the curve of the heat capacity with respect to temperature. The phase transitions took place at (126.16 +/- 0.68) and (178.96 +/- 1.47) K for the sample of acetone, (157.79 +/- 0.95) and (175.93 +/- 0.95) K for methanol, which were corresponding to the solid-solid and the solid-liquid phase transitions of the acetone and the methanol, respectively. And the phase transitions occurred in the temperature ranges of 120 to 190 K and 278 to 280 K corresponding to the solid-solid and the solid-liquid phase transitions of mixture of acetone, cyclohexane and methanol, respectively. The thermodynamic functions and the excess thermodynamic functions of the mixture relative to standard temperature of 298.15 K were derived based on the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature

thermodynamicpropertiesoftheazeotropicmixtureofacetonecyclohexaneandmethanol

Molar heat capacities of the pure samples of acetone, methanol and the azeotropic mixture composed of acetone, cyclohexane and methanol were measured by an adiabatic calorimeter from 78 to 320 K. The solid-solid and solid-liquid phase transitions of the pure samples and the mixture were determined based on the curve of the heat capacity with respect to temperature. The phase transitions took place at (126.16 +/- 0.68) and (178.96 +/- 1.47) K for the sample of acetone, (157.79 +/- 0.95) and (175.93 +/- 0.95) K for methanol, which were corresponding to the solid-solid and the solid-liquid phase transitions of the acetone and the methanol, respectively. And the phase transitions occurred in the temperature ranges of 120 to 190 K and 278 to 280 K corresponding to the solid-solid and the solid-liquid phase transitions of mixture of acetone, cyclohexane and methanol, respectively. The thermodynamic functions and the excess thermodynamic functions of the mixture relative to standard temperature of 298.15 K were derived based on the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature

Thermodynamic Studies of Rod- and Spindle-Shaped beta-FeOOH Crystals

Different morphologies of beta-FeOOH including rod- and spindle-shaped crystals were synthesized via a hydrothermal reaction at low temperature. The molar heat capacities of the obtained samples were determined by a precision automated adiabatic calorimeter over the temperature range of (78 to 390) K. The observed results demonstrated that the change of the molar heat capacity with thermodynamic temperature was different for the rod and spindle-shaped beta-FeOOH crystals. Polynomial equations of the molar heat capacities as a function of temperature were fitted by a least-squares method for the rod- and spindle-shaped beta-FeOOH crystals. Smoothed heat capacities and thermodynamic functions of the obtained samples, such as H(T/K) - H(298.15) and S(T/K) - S(298.15), were Calculated on the basis of the fitted polynomials and the relationships of the thermodynamic functions. In addition, the as-prepared samples were also characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and thermal gravimetric analysis (TGA)

Singlet Oxygen Formation Mechanism for the H₂O₂‑Based Fenton-like Reaction Catalyzed by the Carbon Nitride Homojunction

The singlet oxygen (1O2) oxidation process activated by metal-free catalysts has recently attracted considerable attention for organic pollutant degradation; however, the 1O2 formation remains controversial. Simultaneously, the catalytic activity of the metal-free catalyst limits the practical application. In this study, carbon nitride (HCCN) containing an intramolecular homojunction, a kind of metal-free catalyst, exhibits excellent activity compared to g-C3N4 (CN) and crystalline carbon nitride (HCN) for tetracycline hydrochloride degradation through the H2O2-based Fenton-like reaction. The rate constant for HCCN increased about 16.1 and 8.9 times than that of CN and HCN, respectively. The activity of HCCN was enhanced, and the dominant reactive oxygen species (ROS) changed from hydroxyl radicals (•OH) to 1O2 with an increase in pH from 4.5 to 11.5. A novel formation pathway of 1O2 was revealed. This result is different from the normal reference, in which •OH is always the primary ROS in the H2O2-based Fenton-like reaction. This study may provide a possible strategy for the investigation on the nonradical oxidation process in the Fenton-like reaction