We have shown that many fungi (eukaryotes) exhibit distinct denitrifying activities, although occurrence of denitrification was previously thought to be restricted to bacteria (prokaryotes), and have characterized the fungal denitrification system. It comprises NirK (copper-containing nitrite reductase) and P450nor (a cytochrome P450 nitric oxide (NO) reductase (Nor)) to reduce nitrite to nitrous oxide (N 2 O). The system is localized in mitochondria functioning during anaerobic respiration. Some fungal systems further contain and use dissimilatory and assimilatory nitrate reductases to denitrify nitrate. Phylogenetic analysis of nirK genes showed that the fungal-denitrifying system has the same ancestor as the bacterial counterpart and suggested a possibility of its proto-mitochondrial origin. By contrast, fungi that have acquired a P450 from bacteria by horizontal transfer of the gene, modulated its function to give a Nor activity replacing the original Nor with P450nor. P450nor receives electrons directly from nicotinamide adenine dinucleotide to reduce NO to N 2 O. The mechanism of this unprecedented electron transfer has been extensively studied and thoroughly elucidated. Fungal denitrification is often accompanied by a unique phenomenon, co-denitrification, in which a hybrid N 2 or N 2 O species is formed upon the combination of nitrogen atoms of nitrite with a nitrogen donor (amines and imines). Possible involvement of NirK and P450nor is suggested.

The methanation of CO and CO 2 present in coke oven gas was performed in a fixed-bed catalytic reactor at a reaction temperature between 200 and 400 °C. Different support materials, including SiO 2 , Al 2 O 3 , ZrO 2 , and CeO 2 , were doped with a different percentage of active metals using a standard impregnation and coprecipitation method. The catalysts were characterized using Brunauer−Emmett−Teller analysis, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed desorption techniques. The activity of all samples was tested in terms of the percentage of CO and CO 2 conversion and CH 4 selectivity. The results were analyzed on the basis of the difference in the catalytic performance at different active metal loadings and support materials. The effect of the catalytic support on the reducibility, morphology, and active metal dispersion was investigated. The ZrO 2 −CeO 2 -supported catalyst prepared under coprecipitation can attain 100% CO conversion at around 300 °C and ≥95% CO 2 conversion at 400 °C and has a CH 4 selectivity of 99%.

By retreating the C12A7-O- microporous crystal ([Ca24Al28O64] 4+·4O-) in a high-temperature (1350 °C) and water vapor environment, almost 100% O- and O2 - anions in C12A7-O- have been substituted by the OH- anions, leading to the formation of a high-intensity OH- emission material, [Ca24Al28O64]4+·4OH- (C12A7-OH-). The formation of OH- in C12A7-OH- was identified by investigating the anionic species both on the surface and in the bulk as well as its emission features with Fourier-transform IR absorption, electron paramagnetic resonance, and time-of-flight mass spectra. The concentration of OH- anions in C12A7-OH- is estimated to be more than 7 × 1020 cm-3. Furthermore, a sustainable and stable OH- emission current of 11.7 μA/cm2 from C12A7-OH- has been obtained at a sample surface temperature of 780 °C under an extraction field of 1300 V/cm. The emission features of C12A7-OH-, such as temperature and field effects, have been also investigated. It is expected that the present material could be practically used as an OH- anions storage and generator.

Cost-effective, stable, and highly efficient heterogeneous catalyst is the key challenge for wastewater treatment based on Fenton-like advanced oxidation processes. Perovskite oxides offer new opportunities because of their versatile compositions and flexible physiochemical properties. Herein, a new strategy is proposed that is different from the frequently used alien-metal doping, to tune surface properties of perovskite oxides by nanocompositing perovskite with inert oxide, resulting in improved activity and stability for catalytic oxidation. By in situ modification of LaFeO 3 with inert La 2 O 3 oxide through one-pot synthesis, several important surface properties such as surface defects, H 2 O 2 adsorption capacity, Fe 2+ concentration, and chargetransfer rate were improved, as well as resistance against iron leaching. In performance evaluation, among the various materials, La 1.15 FeO 3 (L 1.15 FO) composite shows the highest Fenton activity (0.0402 min −1 ) for activating H 2 O 2 to oxidize methyl orange, 2.5 times that of the pristine LaFeO 3 . Notably, in situ electron paramagnetic resonance analysis and radical scavenging tests unveil a faster generation of singlet oxygen as the dominant reactive species over L 1.15 FO, consequently a novel non-radical activation mechanism is proposed. Such improved performance is assigned to the strong coupling effect between the nanosized LaFeO 3 and La 2 O 3 in the hybrids, which fine-tune the surface properties of LaFeO 3 perovskite as superior Fenton catalysts.

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