A series of vanadium doped Fe2O3 catalysts were synthesized using the homogeneous precipitation method and subjected to laboratory evaluation for selective catalytic reduction of NO x with NH3 (NH3-SCR). The best Fe0.75V0.25Oδ catalyst with a Fe/V mole ratio of 3/1 exhibited superior catalytic performance, achieving 100% NO x conversion at 200 °C over a wide temperature window from 175 to 400 °C, believed to be the best Fe-based low-temperature NH3-SCR catalyst identified to date. The Fe0.75V0.25Oδ catalyst also showed prominent resistance to high gas hourly space velocity (GHSV; 200 000 h–1) and strong durability to SO2 and H2O. Doping of V was shown to remarkably boost the catalytic activity, due to enhancement of the redox ability and surface acidity. XRD, Raman, and morphology results revealed that the incorporation of V had led to the formation of amorphous FeVO4 and Fe2O3. Coupling XPS and UV–vis diffuse reflectance spectra (DRS) results with DFT, it was discovered that the electron inductive effect between Fe and V generated the charge depletion of Fe, resulting in an improvement of the redox ability, facilitating the oxidation of NO to NO2. Meanwhile, the strong interaction between FeVO4 and Fe2O3 species kept V at a higher valence, beneficial for the adsorption and activation of NH3. The synergistic effect of FeVO4 and Fe2O3 thus improved the low-temperature catalytic activity and lowered the apparent activation energy. Combining in situ diffusion Fourier transform infrared spectroscopy (DRIFTS) results with reaction kinetic studies, it was concluded that the SCR reaction mainly followed the Langmuir–Hinshelwood mechanism below 200 °C, since the consumption of adsorbed NH3 species could be divided into the explicit “standard SCR” and “fast SCR” stages, while an Eley–Rideal mechanism proceeded dominantly at and above 200 °C, in which the adsorbed NH3 species were eliminated by gaseous NO directly and linearly. Both the Brønsted and Lewis acid sites played equivalently significant roles in NH3-SCR reaction.

Electrochemical dechlorination of 1,2-dichloroethane (DCE) is one of the prospective and economic strategies for the preparation of high-value ethylene. However, the exploration of advanced electrocatalysts with high reactivity and selectivity and the identification of their active sites are still a challenge. Herein, a single-atom (SA) Fe–N x –C nanosheet with the presence of a highly efficient Fe–N4 coordination pattern is reported. The as-prepared single-atom electrocatalyst exhibits a higher reactivity and ethylene selectivity for DCE dechlorination reaction than those of the commercially adopted 20% Pt–C catalyst. By a combination of experiments and theoretical calculations, the atomically dispersed Fe center in the Fe–N4 structure was unveiled to be the dominating active site for electrochemical production of ethylene. Our work would offer an approach for the rational development of SA materials and supply crucial insight into the mechanism of ethylene production through the DCE dechlorination reaction.

Nitrogen (N)-doped carbon materials are considered as the most promising alternative to replace noble-metal catalysts for electrocatalytic dechlorination of 1,2-dichloroethane (DCE), which is a promising reaction for industrial production and environmental protection. Unfortunately, the vague cognition of the catalytic active sites limits its further development. Herein, a series of surface N-doped porous carbon materials with adjustable N dopants were synthesized to identify the active sites for electrocatalytic dechlorination of DCE. The as-prepared catalyst showed fascinating DCE electrocatalytic dechlorination activity and ethylene selectivity at −2.75 V (vs SCE) with a current density of 17.94 mA cm–2 geometry and ethylene Faradaic efficiency of 21%. The post hydrogen treatment and X-ray photoelectron spectroscopic analysis experimentally proved that the oxidized N acts as the active site for the dechlorination of DCE to CH2CH2, which was further theoretically confirmed by first-principles calculations. This work would open avenues for the development of N-doped carbon and the production of ethylene in an efficient and environmentally benign manner.

A novel Fe2O3–MnO2/TiO2 catalyst was synthesized using a conventional impregnation method assisted with ethylene glycol and used for NH3–SCR. The catalyst exhibited superior low-temperature activity over a broad temperature window (100–325 °C), low apparent activation energy, and excellent sulfur-poisoning resistance. The characterization results revealed that the catalyst was greatly dispersed with smaller particles, and the partial doping of Fe into the TiO2 lattice thereby led to the formation of the Fe–O–Ti structure, which could strengthen the electronic inductive effect and increase the ratio of surface chemisorption oxygen, resulting in the enhancement of NO oxidation and favoring the low-temperature SCR activity via a “fast SCR” process. The in situ FTIR analysis showed that the NO x adsorption capacity was significantly improved due to the desired dispersion property, further helping both the SCR activity and reaction rate at low temperatures. The present work confirmed that more active sites can be provided on the catalyst surface by modifying the dispersity.

Carbon materials have been recognized as prospective catalysts for the electrocatalytic 1,2-dichloroethane (DCE) dechlorination reaction (DCEDR), which is an economical and environmentally friendly strategy for the control of DCE contamination and production of highly valuable ethylene. However, the precise nature of intrinsic defects (pentagon, heptagon, octagon, armchair edge, and zigzag edge) in carbon-based catalysts for the electrochemical DCEDR has not been reported to date. Herein, theoretical calculations demonstrated that pentagon site showed the lowest energy barrier of 0.12 eV, indicating a much higher electrochemical reactivity and ethylene selectivity of pentagon defect than those of others. The prediction results have been proved experimentally based on a series of defective carbon materials with definitive defect configurations. Therefore, intrinsic defects played a significant role in the electrocatalytic DCEDR and pentagon defect was responsible for the high performance of defective carbon catalysts. This work not only clarifies the nature of intrinsic defects in carbon materials for electrochemical DCEDR but also provides the design principles for the rational preparation of advanced carbon electrocatalysts.