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In this study, the modified activated coke (AC-Tit) was prepared from coals using titanium ore by the blending method with a one-step carbonization–activation process. The results show that the addition of titanium ore affects the physicochemical properties of AC-Tit. The AC-Tit samples have higher V mic and V mic/V tot ratios as well as oxygen and CO functional group. The metal oxides (i.e., FeTiO3, TiO2, Fe2O3, and Fe) were detected on the surface of samples, attributed to the existence of Fe and Ti in the titanium ore. The titanium ore addition improved the desulfurization performance of the AC-Tit effectively; the highest sulfur capacity was 203.3 mg/g, which was much higher than that of the blank sample (120.1 mg/g). After desulfurization, some metal sulfates, i.e., Fe2(SO4)3 and CaSO4, were detected on the AC-Tit samples. When the sample was regenerated, its surface area (S BET) and V mic did not change significantly, the relative content of CO decreased, and COOH increased evidently. In addition, metal sulfates on the AC-Tit samples were not decomposed during the regeneration process. The variation of surface chemical properties of the regenerated AC-Tit caused the reduction of the desulfurization activity after regeneration.

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Oxygen reduction reaction (ORR) remains challenging due to its complexity and slow kinetics. In particular, Pt-based catalysts which possess outstanding ORR activity are limited in application with high cost and ease of poisoning. In recent years, nitrogen-doped graphene has been widely studied as a potential ORR catalyst for replacing Pt. However, the vague understanding of the reaction mechanism and active sites limits the potential ORR activity of nitrogen-doped graphene materials. Herein, density functional theory is used to study the reaction mechanism and active sites of nitrogen-doped graphene for ORR at the atomic level, focusing on explaining the important role of nitrogen species on ORR. The results reveal that graphitic N (GrN) doping is beneficial to improve the ORR performance of graphene, and dual-GrN-doped graphene can demonstrate the highest catalytic properties with the lowest barriers of ORR. These results provide a theoretical guide for designing catalysts with ideal ORR property, which puts forward a new approach to conceive brilliant catalysts related to energy conversion and environmental catalysis.