Low-Temperature Synthesis of Anatase TiO2 Nanoparticles with Tunable Surface Charges for Enhancing Photocatalytic Activity

In this work, the positively or negatively charged anatase TiO[subscript 2] nanoparticles were synthesized via a low temperature precipitation-peptization process (LTPPP) in the presence of poly(ethyleneimine) (PEI) and poly(sodium4- styrenesulfonate) (PSS). X-ray diffraction (XRD) pattern and high-resolution transmission electron microscope (HRTEM) confirmed the anatase crystalline phase. The charges of the prepared TiO[subscript 2], PEI-TiO[subscript 2] and PSS-TiO[subscript 2] nanoparticles were investigated by zeta potentials. The results showed that the zeta potentials of PEI-TiO[subscript 2] nanoparticles can be tuned from +39.47 mV to +95.46 mV, and that of PSS-TiO[subscript 2] nanoparticles can be adjusted from −56.63 mV to −119.32 mV. In comparison with TiO[subscript 2], PSS-TiO[subscript 2] exhibited dramatic adsorption and degradation of dye molecules, while the PEI modified TiO[subscript 2] nanoparticles showed lower photocatalytic activity. The photocatalytic performances of these charged nanoparticles were elucidated by the results of UV-vis diffuse reflectance spectra (DRS) and the photoluminescence (PL) spectra, which indicated that the PSS-TiO[subscript 2] nanoparticles showed a lower recombination rate of electron-hole pairs than TiO[subscript 2] and PEI-TiO[subscript 2].National Natural Science Foundation (China) (21176005

Facile and Scalable Preparation of Graphene Oxide-Based Magnetic Hybrids for Fast and Highly Efficient Removal of Organic Dyes

This study reports the facile preparation and the dye removal efficiency of nanohybrids composed of graphene oxide (GO) and Fe[subscript 3]O[subscript 4] nanoparticles with various geometrical structures. In comparison to previously reported GO/Fe[subscript 3]O[subscript 4] composites prepared through the one-pot, in situ deposition of Fe[subscript 3]O[subscript 4] nanoparticles, the GO/Fe[subscript 3]O[subscript 4] nanohybrids reported here were obtained by taking advantage of the physical affinities between sulfonated GO and Fe[subscript 3]O[subscript 4] nanoparticles, which allows tuning the dimensions and geometries of Fe3O4 nanoparticles in order to decrease their contact area with GO, while still maintaining the magnetic properties of the nanohybrids for easy separation and adsorbent recycling. Both the as-prepared and regenerated nanohybrids demonstrate a nearly 100% removal rate for methylene blue and an impressively high removal rate for Rhodamine B. This study provides new insights into the facile and controllable industrial scale fabrication of safe and highly efficient GO-based adsorbents for dye or other organic pollutants in a wide range of environmental-related applications

Preparation of TiO2 Anatase Nanocrystals by TiCl4 Hydrolysis with Additive H2SO4

A new methodology was developed to synthesize uniform titania anatase nanocrystals by the hydrolysis of titanium chloride in sulfuric acid aqueous solutions at 0–90°C. The samples were characterized by Raman spectroscopy, UV-visible spectroscopy, transmission electron microscopy (TEM), electron diffraction (ED), and an Energy dispersive X-ray spectroscopy (EDS). The effects of the reaction temperature, mole ratio of SO42− to Ti4+, and the calcinations temperature on the particle size and crystal phase were investigated. Depending on the acidity, the hydrolysis temperature, and the calcination temperature, rhombic anatase nanocrystals sizes in the range of 10 nm to 50 nm were obtained. In the additive of sulfuric acid, Raman spectra and electron diffraction confirmed that the nanoparticles are composed of anatase TiO2. No other titania phases, such as rutile or brookite, were detected

Impact of Establishment of National New Area on Carbon Reduction

In response to global climate change, China has incorporated carbon peaking and carbon neutrality into its overall economic and social development. National-level new areas are critical strategic carriers for high-quality regional economic development in China, playing an essential role in promoting carbon reduction. Objectively evaluating the carbon-emission-reduction effect of national-level new areas can help accumulate and promote China's low-carbon construction experience, and thus, comprehensively facilitate greening and ecological civilization construction. In this study, the impact of the establishment of national-level new areas on carbon emissions in their respective cities were investigated using the difference-in-difference method. The findings show that: 1) the establishment of a national-level new area can significantly minimize the carbon emissions in the city in which it is located, and after three years of establishment, it will have a significant long-term inhibitory effect on the carbon emissions of the city. This conclusion is still valid after a series of robustness tests, such as propensity score matching + difference-in-difference; 2) The national-level new area policy mainly reduces carbon emissions in a city through technological and energy-saving effects but cannot yet reduce them by adjusting the industrial structure. 3) The impact of the establishment of national-level new areas on the carbon emissions of surrounding cities shows an "∽" trend of increasing first, then decreasing, and subsequently increasing. It has a significant carbon-reduction effect on cities within the range of 200-250 km, indicating that national-level new areas can help promote carbon-emission reduction in surrounding cities. 4) The national-level new area policy has a higher carbon-emission-reduction effect on northern cities than on southern cities. The single-city layout model of the national-level new area has a significant carbon-emission-reduction effect on the host city, whereas the dual-city layout model does not significantly reduce the carbon emissions in the host city. This study investigated the carbon-emission-reduction effect of national-level new area policies and examined carbon-emission reduction in the national-level new areas of pilot cities through technological and energy-saving effects. This study helps to improve the theoretical understanding of national-level new area policies and carbon-emission impact mechanisms and provides a policy reference for China's promotion of the "dual-carbon" strategy

The Comparison of Samples Prepared under Various Hydrolysis Conditions.

<p>The Comparison of Samples Prepared under Various Hydrolysis Conditions.</p

EDS of Sample 1 after Calcination at 400°C for 2 Hours.

<p>EDS of Sample 1 after Calcination at 400°C for 2 Hours.</p

Comparison of the Raman spectrum of the samples after calcinations at 600°C: sample 1, sample 2, sample 3, sample 4, sample 5, sample 6.

<p>Comparison of the Raman spectrum of the samples after calcinations at 600°C: sample 1, sample 2, sample 3, sample 4, sample 5, sample 6.</p

Extinction spectra of sample 1 calcinated at 400 and 600°C.

<p>Extinction spectra of sample 1 calcinated at 400 and 600°C.</p

ED images of the samples, (1) sample 1 calcinated at 400°C, (2) sample 2 calcinated at 400°C, (3) sample 1 calcinated at 600°C, (4) sample 2 calcinated at 600°C.

<p>ED images of the samples, (1) sample 1 calcinated at 400°C, (2) sample 2 calcinated at 400°C, (3) sample 1 calcinated at 600°C, (4) sample 2 calcinated at 600°C.</p