Pt on Atomic-Layered WO3 Islands: Electronic Tuning of Platinum-Tungsten Heterostructures for Highly Efficient Low-Temperature VOC Combustion.

Adjusting the electronic state of noble metal catalysts on a nanoscale is crucial for optimizing the performance of nanocatalysts in many important environmental catalytic reactions, particularly in volatile organic compound (VOC) combustion. This study reports a novel strategy for optimizing Pt catalysts by modifying their electronic structure to enhance the electron density of Pt. The research illustrates the optimal 0.2Pt-0.3W/Fe2O3 heterostructure with atomic-thick WO3 layers as a bulking block to electronically modify supported Pt nanoparticles. Methods such as electron microscopy, X-ray photoelectron spectroscopy, and in situ Fourier transform infrared spectroscopy confirm Pt's electron-enriched state resulting from electron transfer from atomic-thick WO3. Testing for benzene oxidation revealed enhanced low-temperature activity with moderate tungsten incorporation. Kinetic and mechanistic analyses provide insights into how the enriched electron density benefits the activation of oxygen and the adsorption of benzene on Pt sites, thereby facilitating the oxidation reaction. This pioneering work on modifying the electronic structure of supported Pt nanocatalysts establishes an innovative catalyst design approach. The electronic structure-performance-dependent relationships presented in this study assist in the rational design of efficient VOC abatement catalysts, contributing to clean energy and environmental solutions.

Enhancing Benzene Combustion Activity through Preferential Platinum Atom Exposure via Strategic Pt-Cu Alloying.

Volatile organic compounds such as benzene are hazardous air pollutants that require effective elimination. Noble metal-based catalysts exhibit high benzene combustion activity, but their prohibitive cost necessitates strategies to enhance utilization efficiency. This study investigates a Pt-Cu alloy catalyst for improved benzene combustion by preferentially exposing Pt active sites through Cu alloying. Aberration-corrected scanning transmission electron microscopy and X-ray spectroscopy characterize the nanoscale distribution and enrichment of Pt on the alloy surface. Kinetic measurements demonstrate substantially enhanced activity compared with Pt catalysts, attributed to increased Pt metallic site exposure rather than alteration of the reaction mechanism. In situ Fourier transform infrared (FTIR) spectroscopy reveals a higher abundance of terrace-like Pt sites in the alloy, beneficial for benzene adsorption. Partial pressure dependence analyses indicate competitive adsorption of benzene and O2, following Langmuir-Hinshelwood kinetics. These findings provide conceptual insights into tuning surface composition in bimetallic catalysts to optimize noble metal efficiency, with broad applicability for sustainable catalytic process advancement.

Surface design of g-C3N4 quantum dot-decorated TiO2(001) to enhance the photodegradation of indoor formaldehyde by experimental and theoretical investigation.

Formaldehyde (CHOH), a common volatile organic compound, causes many adverse effects on human health. The highly exposed TiO2(001) facet possesses a high photodegradation efficiency of CHOH due to its excellent ability to trap photogenerated holes and high density of surface unsaturated Ti atoms (Ti5c) to bind CHOH. However, the rapid recombination of photoinduced electron-hole pairs of TiO2(001) limits the photodegradation efficiency. We adopted a strategy of decorating TiO2(001) with g-C3N4 quantum dots (QDs), exploiting the quantum effect of g-C3N4QDs and their combined staggered band structure. This decoration improves the photocatalytic activity of TiO2(001). Moreover, the chemical configuration of g-C3N4QDs/TiO2(001) and the combination mode between the g-C3N4QDs and TiO2(001) support were explored in detail using high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations. Following the physiochemical characteristic results, the transport mechanism of photoinduced carriers was further analyzed by ultraviolet photoelectron spectroscopy (UPS), electron paramagnetic resonance (EPR), and Heyd-Scuseria-Ernzerh (HSE) exchange-correlation functional calculations. Finally, the performance and reaction mechanism of the photodegradation of CHOH by TiO2(001) and g-C3N4QDs/TiO2(001) were thoroughly investigated. The results show that the g-C3N4QDs were composed of an N-defect tri-s-triazine supported by TiO2(001) via a strong C-O-Ti chemical bond, which accelerated the separation of photoinduced carriers through a Z-scheme route. The photodegradation and mineralization efficiencies of CHOH were significantly promoted by 30% and 60% for g-C3N4QDs/TiO2(001) compared with those of TiO2(001). The photodegradation mechanism proceeded as CHOH - dioxymethylene - formate - carbonate - CO2. This study provides a surface engineering means to design highly active modified TiO2 for CHOH photodegradation.

Pt single atoms and defect engineering of TiO2-nanosheet-assembled hierarchical spheres for efficient room-temperature HCHO oxidation.

Achieving high atomic utilization and low cost of desirable Pt/TiO2 catalysts is a major challenge for room temperature HCHO oxidation. Here, the strategy of anchoring stable Pt single atoms by abundant oxygen vacancies over TiO2-nanosheet-assembled hierarchical spheres (Pt1/TiO2-HS) was designed to eliminate HCHO. A superior HCHO oxidation activity and CO2 yield (∼100% CO2 yield) at relative humidity (RH) > 50% over Pt1/TiO2-HS is achieved for long-term run. We attribute the excellent HCHO oxidation performance to the stable isolated Pt single atoms anchored on the defective TiO2-HS surface. The Ptδ+ on the Pt1/TiO2-HS surface has a facile intense electron transfer with the support by forming Pt-O-Ti linkages, driving HCHO oxidation effectively. Further in situ HCHO-DRIFTS revealed that the dioxymethylene (DOM) and HCOOH/HCOO- intermediates were further degraded via active OH- and adsorbed oxygen on the Pt1/TiO2-HS surface, respectively. This work may pave the way for the next generation of advanced catalytic materials for high-efficiency catalytic HCHO oxidation at room temperature.

A green strategy to recycle the waste PP melt-blown materials: From 2D to 3D construction.

The demand for polypropylene (PP) melt-blown materials has dramatically increased due to the COVID-19 pandemic. It has caused serious environmental problems because of the lack of effective treatment for the waste PP melt-blown materials. In this study, we propose a green and sustainable recycling method to create PP sponges from waste PP melt-blown material for oil spill cleaning by freeze-drying and thermal treatment techniques. The recycling method is simple and without secondary pollution to the environment. The developed recycling method successfully transforms 2D laminar dispersed PP microfibers into elastic sponges with a 3D porous structure, providing the material with good mechanical properties and promotes its potential application in the field of oil spill cleaning. The morphology structure, thermal properties, mechanical properties, and oil absorption properties are tested and characterized. The PP sponges with a three-dimensional porous network structure show an exceedingly low density of >0.014 g/cm3, a high porosity of <98.77 %, and a high water contact angle range of 130.4-139.9°. Moreover, the PP sponges own a good absorption capacity of <47.61 g/g for different oil and solvents. In particular, the compressive modulus of the PP sponges is 33.59-201.21 kPa, which is higher than that of most other fiber-based porous materials, indicating that the PP sponges have better durability under the same force. The excellent comprehensive performance of the PP sponges demonstrates the method developed in this study has large application potential in the field of the recycle of waste PP melt-blown materials.

Effect of hydrothermal aging temperature on a Cu-SSZ-13/H-SAPO-34 composite for the selective catalytic reduction of NO x by NH3.

Cu-SSZ-13 suffers activity loss after hydrothermal treatment at high temperatures, particularly above 850 °C. The stability of Cu-SSZ-13 can be enhanced by compositing with H-SAPO-34. This work investigates the effect of aging temperature on the composites. For the structure, the extra-framework P in H-SAPO-34 migrates and interacts with the Al in Cu-SSZ-13, forming a new framework P-Al bond. This interaction is enhanced with the increment of the aging temperature. For the cupric sites, the aging at 750 °C results in the agglomeration of Cu2+ ions to CuO. However, the sample aged at 800 °C exhibits higher activities than that aged at 750 °C, which might be attributed to the increased formation of framework P-Al bonds promoting the redispersion of CuO to Cu2+ ions. The composite suffers severe deactivation due to the significant loss of Cu2+ ions after aging at 850 °C.