H-Implanted Pd Icosahedra for Oxygen Reduction Catalysis: From Calculation to Practice

Although palladium(Pd)has gradually emerged as the most likely candidate to replace platinum(Pt)in the oxygen reduction reaction(ORR),the specific electronic structure of conventional Pd results in too strong Pd–O binding strength and unsatisfactory ORR performance.Herein,guided by density functional theory,we have explored a strategy to expand lattice spacing by implanting hydrogen(H)atoms in Pd nanocrystals(NCs),which realizes decreased electron density to boost ORR.

Catalysis of dioxygen reduction at soluble polyaniline modified electrode

A reflux-treatment of soluble polyaniline(SPA)in dimethylformamide(DMF)containing CoCl_2 yields an active catalyst for dioxygen reduction which can be adsorbed on the electrode surface firmly.The catalytic reduction of dioxygen at the glassy carbon(GC)electrode modified by the cata- lyst was studied with cyclic voltammetry(CV),rotating disk electrode(RDE)and rotating ring-disk electrode(RRDE).The kinetic process of dioxygen reduction at the modified electrode was analyzed with a new RRDE theory dealing with a nondiffusion-controlled process on ring electrode.The rate constants for each scheme of dioxygen reduction were calculated,showing that only 2-electron reduction to H_2O_2 was conducted at the modified electrode.The effect of solution acidity on the electrocatalytic behaviour for dioxygen reduction was investigated.A possibility of initiating catalytic activity for dioxygen reduction was explored with ESCA method.

Synergetic catalysis of ceria and titania for selective reduction of NO

The promotional effect of the interaction between titania and ceria on the catalytic performance for selective reduction of NO was studied.The catalysts,CeO 2,TiO 2,CeO 2 /TiO 2 and Ti x Ce 1-x O 2,were synthesized and tested in NH 3-Selective catalytic reduction（SCR） of NO,and the samples were characterized by the Brunaller,Emmett and Teller（BET absorbed gas N 2）,X-ray diffraction（XRD）,high resolution transmission electron microscopy（HR-TEM）,and temperature programmed desorption（TPD NH 3） techniques.The improvement mechanism of the interaction between the titania and ceria had been explored and discussed from two aspects of micro-structure and surface acidity.The interaction between the titania and ceria greatly improved the catalytic activity but had little effect on the active temperature.It was first reported that the acid amount determined the catalytic activity and the acid strength determined the active temperature for NH 3-SCR of NO.

Electronegativity-assisted optimized electronic structure of functionalized-Pt catalysts for boosting oxygen reduction kinetics

Opportunity to harmonize aspects of oxygen reduction reaction(ORR)performance and structure,and morphology,as well as composition,is urgent for the commercialization of proton exchange membrane fuel cells.Herein,we demonstrate the design and synthesis of a functionalized-supported-Pt catalyst(Pt@HNC)featuring a hollow nitrogen-modified dodecahedral carbon substrate obtained by a stress-induced-shrink tailoring route.The as-obtained Pt@HNC catalyst possesses enhanced ORR per-formance,in particular with half-wave potential,mass activity(MA)and specific activity,which greatly exceed the commercial Pt/C.The density functional theory(DFT)calculations further confirmed that the charge redistribution induced by the electronegativity differences improved the electron interaction between Pt and HNC support.The optimized electronic structure of Pt weakens the reaction energy barrier on the Pt@HNC surface and adsorption of^(*)OH species,thus cooperatively improving the intrinsic activity toward ORR.Additionally,our work indeed provides a guide for the future design of functional nanomaterials in the field of catalysts and clean energy.

Structural revolution of atomically dispersed Mn sites dictates oxygen reduction performance

An efficient preparation and local coordination environment regulation of isolated single-atom sites catalysts(ISASC)for improved activity is still challenging.Herein,we develop a solid phase thermal diffusion strategy to synthesize Mn ISASC on highly uniform nitrogen-doped carbon nanotubes by employing MnO_(2) nanowires@ZIF-8 core-shell structure.Under high-temperature,the Mn species break free from core-MnO_(2) lattice,which will be trapped by carbon defects derived from shell-ZIF-8 carbonization,and immobilized within carbon substrate.Furthermore,the poly-dispersed Mn sites with two nitrogen-coordinated centers can be controllably renovated into four-nitrogen-coordinated Mn sites using NH3 treatment technology.Both experimental and computational investigations indicate that the symmetric coordinated Mn sites manifest outstanding oxygen reduction activity and superior stability in alkaline and acidic solutions.This work not only provides efficient way to regulate the coordination structure of ISASC to improve catalytic performance but also paves the way to reveal its significant promise for commercial application.

Ruthenium-promoted reductive transformation of CO2

The reductive transformation of CO_2 to energy related products including formic acid, CO, formamide, methanol and methylamine could be a promising option to supply renewable energy. In this aspect, ruthenium has found wide application in hydrogenation of various carbonyl groups, and has successfully been applied to reductive transformation of CO_2 with high catalytic efficiency and excellent selectivity. In addition, ruthenium complexes have also served as effective photosensitizers for CO_2 photoreduction.Classified by reductive products, this review summarizes and updates advances in the Ru-catalyzed reduction of CO_2 along with catalyst development on the basis of mechanistic understanding at a molecular level.