Hydrogen
ion is an attractive charge carrier for energy storage
due to its smallest radius. However, hydrogen ions usually exist in
the form of hydronium ion (H3O+) because of
its high dehydration energy; the choice of electrode materials is
thus greatly limited to open frameworks and layered structures with
large ionic channels. Here, the desolvation of H3O+ is achieved by using anatase TiO2 as anodes, enabling
the H+ intercalation with a strain-free characteristic.
Density functional theory calculations show that the desolvation effects
are dependent on the facets of anatase TiO2. Anatase TiO2 (001) surface, a highly reactive surface, impels the desolvation
of H3O+ into H+. When coupled with
a MnO2 cathode, the proton battery delivers a high specific
energy of 143.2 Wh/kg at an ultrahigh specific power of 47.9 kW/kg.
The modulation of the interactions between ions and electrodes opens
new perspectives for battery optimizations.
Fly ash emissions caused by coal combustion have been increasing
for many years, causing serious environmental pollution. Coal combustion
also causes large amounts of NO
x
to be
emitted to the atmosphere, and this has caused environmental problems
such as acid rain, which cannot be ignored. The denitrification catalyst
V2O5/WO3–TiO2 gives
a good denitrification efficiency at a high temperature, but the catalyst
has poor efficiency and is difficult to use at low temperatures (100–300
°C). Therefore, we introduce a new method based on the use of
fly ash to control NO
x
output. We used
a two-step alkali hydrothermal method to prepare SBA-15 mesoporous
molecular sieves from fly ash obtained from a thermal power plant
in Inner Mongolia (China). A series of bimetallic iron and manganese
oxides were supported on the fly-ash-derived SBA-15 catalyst, and
excellent NO conversion was found for selective catalytic reduction
(SCR) of NO with NH3 at low temperatures. The catalysts
were characterized by XRD, XPS, NH3-, O2-, and
CO2-TPD, H2-TPR, BET analysis, SEM, TEM, and
DRIFT spectroscopy. The denitration activity and denitration mechanism
over the catalysts are discussed. The mechanisms of NO reduction and
N2O formation over Mn/SBA-15 and Fe-Mn/SBA-15 were investigated
through in situ DRIFT studies and a transient reaction study. The
strong oxidation, low acidity, and high basicity of the Fe-Mn/SBA-15
catalyst contributed to a large amount of nitrate being produced during
the catalysis. The nitrate decomposed to produce N2O, resulting
in a decrease in N2 selectivity. The denitration mechanism
of the Fe-Mn/SBA-15 catalyst in the SCR reaction followed Langmuir–Hinshelwood,
Eley–Rideal, and Mars–van Krevelen mechanisms.
Further applications of photocatalysis were limited by the high recombination probability of photo-induced electron–hole pairs in traditional titanium dioxide nanoparticles (TiO2 NPs). Herein, we modified them with rare earth metal via a facile sol–gel method, using tetrabutyl titanate as a precursor and terbium (III) nitrate hexahydrate as terbium (Tb) source. The resulting samples with different Tb doping amounts (from 0 to 2%) have been characterized by X-ray diffraction, UV–visible diffuse reflectance spectroscopy, X-ray photo-electron spectroscopy and a scanning electron microscope. The photocatalytic performance of Tb-doped TiO2 was evaluated by the degradation of methylene blue. The effects of Tb doping amount and initial pH value of solution were investigated in detail. The composite with Tb doping amount of 1.0 wt% showed the highest photocatalytic performance. It exhibited approximately three times enhancement in photocatalytic activity with a reaction rate constant of 0.2314 h−1 when compared with that of commercial P25 (0.0827 h−1). In addition, it presented low toxicity on zebrafishes with 96 h-LC50 of 23.2 mg l−1, and has been proved to be reusable for at least four cycles without significant loss of photocatalytic activity. A probable photocatalytic mechanism of Tb-doped TiO2 was proposed according to the active species trapping experiments. The high photocatalytic performance, excellent reusability and low toxicity of Tb-doped TiO2 indicated that it is a promising candidate material in the future treatment of dye wastewater.
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