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In this work, a novel heterojunction composite Ag2S/KTaxNb1-xO3 was designed and synthesized through a combination of hydrothermal and precipitation procedures. The Ta/Nb ratio of the KTaxNb1-xO3 and the Ag2S content were optimized. The best 0.5% Ag2S/KTa0.5Nb0.5O3 (KTN) sample presents an enhanced photocatalytic performance in ammonia synthesis than KTN and Ag2S. Under simulated sunlight, the NH3 generation rate of 0.5% Ag2S/KTN reaches 2.0 times that of pure KTN. Under visible light, the reaction rate ratio of the two catalysts is 6.0. XRD, XPS, and TEM analysis revealed that Ag2S was intimately decorated on the KTN nanocubes surface, which promoted the electron transfer between the two semiconductors. The band structure investigation indicated that the Ag2S/KTN heterojunction established a type-II band alignment with intimate contact, thus realizing the effective transfer and separation of photogenerated carriers. The change in charge separation was considered as the main reason for the enhanced photocatalytic performance. Interestingly, the Ag2S/KTN composite exhibited higher NH3 generation performance under the combined action of ultrasonic vibration and simulated sunlight. The enhanced piezo-photocatalytic performance can be ascribed that the piezoelectric effect of KTN improved the bulk separation of charge carriers in KTN. This study not only provides a potential catalyst for photocatalytic nitrogen fixation but also shows new ideas for the design of highly efficient catalysts via semiconductor modification and external field coupling.

In this work, Ag/Bi5O7I nanocomposite was prepared and firstly applied in piezo/photocatalytic reduction of N2 to NH3 and methyl orange (MO) degradation. Bi5O7I was synthesized via a hydrothermal-calcination method and shows nanorods morphology. Ag nanoparticles (NPs) were photo deposited on the Bi5O7I nanorods as electron trappers to improve the spatial separation of charge carriers, which was confirmed via XPS, TEM, and electronic chemical analyses. The catalytic test indicates that Bi5O7I presents the piezoelectric-like behavior, while the loading of Ag NPs can strengthen the character. Under ultrasonic vibration, the optimal Ag/Bi5O7I presents high efficiency in MO degradation. The degradation rate is determined to be 0.033 min−1, which is 4.7 folds faster than that of Bi5O7I. The Ag/Bi5O7I also presents a high performance in piezocatalytic N2 fixation. The piezocatalytic NH3 generation rate reaches 65.4 μmol L−1 g−1 h−1 with water as a hole scavenger. The addition of methanol can hasten the piezoelectric catalytic reaction. Interestingly, when ultrasonic vibration and light irradiation simultaneously act on the Ag/Bi5O7I catalyst, higher performance in NH3 generation and MO degradation is observed. However, due to the weak adhesion of Ag NPs, some Ag NPs would fall off from the Bi5O7I surface under long-term ultrasonic vibration, which would greatly reduce the piezoelectric catalytic performance. This result indicates that a strong binding force is required when preparing the piezoelectric composite catalyst. The current work provides new insights for the development of highly efficient catalysts that can use multiple energies.

The selective hydrogenolysis of glycerol to 1,3-propanediol (1,3-PDO) with high added value is attraction but challenging. Pt-WOx-based catalysts have been extensively studied in the selective hydrogenolysis of glycerol. The catalyst support and the physicochemical state of WOx play important roles on this reaction. In this paper, Pt-WOx catalysts supported on TiO2 with different crystal forms were prepared and studied for their catalytic performance in hydrogenolysis of glycerol. It was observed that the catalytic performance of anatase-type (A-type) TiO2-supported catalyst (Pt/W/A-Ti) is much better than that of the rutile-type (R-type) TiO2 catalyst (Pt/W/R-Ti) due to its higher stability. Furthermore, the influence of W loading amount and state were thoroughly investigated for the Pt/W/A-Ti catalysts, and Pt/W/A-TiO2 with 5 wt% loading of WOx achieved the best catalytic performance (100% conversion of glycerol and 41% yield of 1,3-PDO under the optimal reaction conditions), owing to the suitable WOx domains and high dispersion of W species, as evidenced by XRD patterns and TEM images. Mechanism study by in-situ DRIFTS experiments indicated that glycerol was first converted to 3-hydroxypropanal and then converted to 1,3-PDO through subsequent reactions.

In this study, a new competency assessment system was developed for the blended learning course "Organic Chemistry Laboratory". The system utilized a mastery transcript evaluation model and incorporated the Structure of Observed Learning Outcomes (SOLO) taxonomy and Primary Trait Analysis (PTA) scale method. With this system, students can clearly understand the proficiency level that they need to reach both online and in class to achieve their desired course grades. The impact of the assessment method was analyzed by examining 20 sophomore students from a university. The findings highlighted that this new competency-based rubric offers several advantages, such as providing a more comprehensive assessment of students' abilities, encouraging the development of their enthusiasm for independent learning, and improving their concentration during experiments. All of these benefits contribute to developing their overall competency skills.

In this work, a novel heterojunction composite Ag2S/KTaxNb1-xO3 was designed and synthesized through a combination of hydrothermal and precipitation procedures. The Ta/Nb ratio of the KTaxNb1-xO3 and the Ag2S content were optimized. The best 0.5% Ag2S/KTa0.5Nb0.5O3 (KTN) sample presents an enhanced photocatalytic performance in ammonia synthesis than KTN and Ag2S. Under simulated sunlight, the NH3 generation rate of 0.5% Ag2S/KTN reaches 2.0 times that of pure KTN. Under visible light, the reaction rate ratio of the two catalysts is 6.0. XRD, XPS, and TEM analysis revealed that Ag2S was intimately decorated on the KTN nanocubes surface, which promoted the electron transfer between the two semiconductors. The band structure investigation indicated that the Ag2S/KTN heterojunction established a type-II band alignment with intimate contact, thus realizing the effective transfer and separation of photogenerated carriers. The change in charge separation was considered as the main reason for the enhanced photocatalytic performance. Interestingly, the Ag2S/KTN composite exhibited higher NH3 generation performance under the combined action of ultrasonic vibration and simulated sunlight. The enhanced piezo-photocatalytic performance can be ascribed that the piezoelectric effect of KTN improved the bulk separation of charge carriers in KTN. This study not only provides a potential catalyst for photocatalytic nitrogen fixation but also shows new ideas for the design of highly efficient catalysts via semiconductor modification and external field coupling. [ABSTRACT FROM AUTHOR]

High-performance KNbO3/g-C3N4 composite was prepared via a feasible method and first applied in photocatalytic H2 production from water–methanol solution under irradiation of visible light. The structure and optical property of the synthesized composite were investigated by various techniques, including XRD, XPS, FT-IR, TEM, SEM, DRS, PL, and an electrochemical method. Results indicated that the combining of KNbO3 with g-C3N4 did not affect the optical absorption. However, strong interaction between the two semiconductors was observed, which promotes the fabrication of a heterojunction structure and subsequently improves the separation of photogenerated electrons and holes. Hence, KNbO3/g-C3N4 photocatalyst displayed obviously higher photoactivity than pristine g-C3N4. The photocatalytic hydrogen production rate for the optimal KNbO3/g-C3N4 composite (7.4 wt% KNbO3/g-C3N4) is 180 lmol gcat -1 h-1, which is about 3.0 times that of pristine g-C3N4. Cycling tests further proved that KNbO3/g-C3N4 showed good photocatalytic stability. Additionally, the effect of hole sacrificial agent on the photocatalytic activity was also investigated. The KNbO3/g-C3N4 sample showed better performance in the presence of methanol than triethanolamine or EDTA-Na. [ABSTRACT FROM AUTHOR]

This paper presents a novel visible-light-driven catalyst, a SO42–/MoOx/MgF2composite, which was synthesized by a simple solution method. Multiple techniques, including Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS) were applied to investigate the physical and photophysical properties of the catalysts. The photocatalytic activities were evaluated in the degradation of acetone in gas phase. In the photodegradation of acetone, the highest conversion was obtained over a catalyst containing 5 mol % molybdenum. The XRD and Raman characterizations indicate that the molybdenum oxide was highly dispersed in the MgF2matrix. These MoOxspecies might be the active sites of the catalysts, which is the reason for the visible-light response of the composite catalyst. The MgF2matrix acts to isolate the MoOxspecies and retard the electron–hole pair recombination. When the molybdenum concentration is >5 mol %, crystalline MoO3phase was observed. The large MoO3particle would decrease the separation efficiency. Thus, the photocatalytic activity was reduced. Besides the molybdenum concentration, the calcination temperature also shows a great effect on the activity. A sulfated 5 mol % MoOx/MgF2catalyst that was calcined at 350 °C showed the highest photocatalytic activity. Based on the results of the characaterization, the origin of the high activity was discussed. The light absorption ability and the MoOxsize effect are considered as the key factors. [ABSTRACT FROM AUTHOR]