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Doping foreign metal ions into catalysts is considered as an effective approach to optimize the catalytic sites and improve their performance. Here, we develop and demonstrate the concept of rare-earth elemental doping by Ce into host catalysts of CoP in modulating their electronic structures and decreasing their adsorption free energy of hydrogen for the enhanced hydrogen evolution reaction (HER) performance via a complementary theoretical and experimental approach. In contrast to undoped catalysts, the Ce-doping can facilitate lower overpotential, Tafel slope and charge transfer resistance as well as larger electrochemically active surface area and turnover frequency to deliver superb catalytic activity and stability. In particular, the catalyst with optimized doping amount exhibits ultra-low overpotentials of 54 and 92 mV at 10 mA cm −2 in acidic and basic media, respectively, among many recently-reported CoP-based catalysts. Doping Ce into CoP not only illustrates benefits in improving the catalytic property for HER, but also opens up a novel view of doping rare earth elements into electrocatalysts for regulating their physiochemical and electrochemical properties. [ABSTRACT FROM AUTHOR]

• Supported bimetallic catalysts typically possess superior performances than monometal catalysts and the impregnation method has been widely applied for the bimetallic catalyst preparations. • Impregnation sequences could play their significant roles on the physical and chemical properties of supported bimetallic catalysts. • A host of characterizations from impregnation sequential effects were briefly evaluated by reviewing the recent representative literatures. • The investigation of the nature of active sites and the structural dynamics on bimetallic catalysts are prospected accordingly to enhance the fundamental understanding of sequential influences. • The appropriate measurement of reaction rates is much required to compare the bimetallic catalysts that are prepared by different sequences of impregnations. Supported bimetallic catalysts have been paid great attention regarding their excellent catalytic performances in chemical process. Notably, comparing to monometallic catalysts, the synergetic properties of dual-metal-based materials demonstrate unique physiochemical functionalities that single metal materials do not possess. The preparation of supported bimetallic materials is widely conducted with applying the impregnation method because of the straightforward and inexpensive technique. Wherein, the impregnation of dual metals on support could either undergo co-impregnation or sequential impregnations. It has been frequently reported that there are substantial differences in physiochemical properties and catalyst performances by impregnation sequences. Specifically, during the investigation of various sequential impregnated bimetallic catalysts, a host of characterization strategies are employed to compare the physical and chemical properties that play vital role to impact the catalyst activity/selectivity/stability. However, it is still not well understood regarding the impregnation sequential effects, such as the nature of bimetallic active sites and the dynamics of bimetallic surface structures along with reaction progress. This presenting perspective article is devoted to take a succinct review regarding the general sequential impacts on the physiochemical properties and further profoundly address the research outlook in this topic. [Display omitted]. [ABSTRACT FROM AUTHOR]

Highlights: [•] We explore that the remarkably catalytic role in which nitric acid plays in the hydrolysis of SO3. [•] We elucidate the reaction mechanisms of the SO3 with H2O in the presence of nitric acid. [•] Of great importance is estimated for the formation of sulfuric acid with the assistance of nitric acid in the atmosphere. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of Mn doping size over Al 2 O 3 on NO oxidation activity were elucidated. • Mn SACs/Cs -Al 2 O 3 exhibits a superior NO-NO 2 capacity compared with Mn NPs -Al 2 O 3. • The coordination environment of Mn species significantly affects the mobility of O sur. • Reducing Mn size from NPs to SACs/Cs promotes labile nitrate species formation. The exploitation of transitional metal catalysts for high-efficient conversion of NO to NO 2 still persists as an imperative issue due to the high cost of currently used Pt–based catalysts. Herein, we report a TEA-modification strategy to anchor Mn single atoms/clusters on Al 2 O 3 (Mn/Al 2 O 3 -T) for NO oxidation. Activity tests show that Mn/Al 2 O 3 -T (T 83 = 275 °C) displays a superior NO-to-NO 2 capacity compared with the unmodified Mn nanoparticle on Al 2 O 3 (Mn/Al 2 O 3 -B, T 66 = 300 °C) and Pt/Al 2 O 3 (T 43 = 350 °C) counterparts. Comprehensive characterization and DFT calculations discover that the effective adjustment of TEA can promote the generation of coordination unsaturated Mn sites with elongated Mn-O bonds, which can improve the mobility of surface lattice oxygen and facilitate the activation of molecular oxygen. Additionally, reducing Mn size from nanoparticles to single atoms/clusters favors the formation of labile nitrate species and facile desorption of NO 2 , thereby regenerating active sites and accelerating overall NO oxidation reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The oxygen migration properties of Fe 2 O 3 (oxygen carrier) were systematically investigated. • The matching problem of oxygen migration rate with the surface catalytic reaction rate was studied. • A suitable concentration of oxygen vacancies is found to be beneficial for the chemical looping reforming of methane to syngas. The chemical looping reforming of methane to syngas is of great significance to the sustainable development of energy and environment, where the oxygen carrier (OC) is the core element of this technology. To study the oxygen migration properties of OCs and the matching problem of oxygen migration rate with the surface catalytic reaction rate, we present a theoretical study by taking the abundant and cheap α-Fe 2 O 3 as the model OC. It is found that the migration rate of lattice oxygen and the dissociation of methane will be enhanced as the concentration of surface oxygen vacancy increases. By comparing the oxygen migration rate with the methane dissociation rate, we reveal that the two rates can match well at a low surface oxygen vacancy concentration, which is the key to the selective production of syngas. Lower or higher surface oxygen vacancy concentration will lead to the products towards carbon dioxide or coke. [ABSTRACT FROM AUTHOR]