High Rate and Long Lifespan Sodium‑Organic Batteries Using Pseudocapacitive Porphyrin Complexes‑Based Cathode

Sodium-organic batteries utilizing natural abundance of sodium element and renewable active materials gain great attentions for grid-scale applications.However,the development is still limited by lack of suitable organic cathode materials with high electronic conductivity that can be operated stably in liquid electrolyte.Herein,we present 5,15-bis(ethynyl)-10,20-diphenylporphyrin(DEPP)and[5,15-bis(ethynyl)-10,20-diphenylporphinato]copper(II)(CuDEPP)as new cathodes for extremely stable sodium-organic batteries.The copper(II)ion partially contributes the charge storage and significantly stabilizes the structure of porphyrin complex for electrochemical energy storage.In situ electrochemical stabilization of organic cathode with a lower charging current density was identified which enables both improved high energy density and power density.An excellent longterm cycling stability up to 600 cycles and an extremely high power density of 28 kW kg−1 were achieved for porphyrin-based cathode.This observation would open new pathway for developing highly stable sodium-organic cathode for electrochemical energy storage.

Density Functional Theoretical Studies on the Methanol Adsorption and Decomposition on Ru（0001） Surfaces

Periodic density functional theory（DFT） calculations are presented to describe the adsorption and decomposition of CH3OH on Ru（0001） surfaces with different coverages, including p（3 ×2）, p（2×2）, and p（2× 1） unit cells, corresponding to monolayer（ML） coverages of 1/6, 1/4, and 1/2, respectively. The geometries and energies of all species involved in methanol dissociation were analyzed, and the initial decomposition reactions of methanol and the subsequent dehydrogenations reactions of CH3O and CH2OH were all computed at 1/2, 1/4, and 1/6 ML coverage on the Ru（0001） surface. The results show that coverage exerts some effects on the stable adsorption of CH30, CH2OH, and CH3, that is, the lower the coverage, the stronger the adsorption. Coverage also exerts effects on the initial decomposition of methanol. C-H bond breakage is favored at 1/2 ML, whereas C-H and O--H bond cleavages are preferred at 1/4 and 1/6 ML on the Ru（0001） surface, respectively. At 1/4 ML coverage on the Ru（0001） surface, the overall reaction mechanism can be written as 9CH3OH ,3CH30＋6CH2OH＋9H ,6CH20＋3CHOH＋18H , 7CHO＋COH＋CH＋OH＋26H → 8CO＋C＋O＋36H.

A DFT＋U Investigation on Methylamine Decomposition Catalyzed by Pt4 Cluster Supported on Oxygen Defective Rutile（110） TiO2

The adsorption and decomposition mechanisms of methylamine catalyzed by Pt4 cluster supported on ruffle（110） titania[namely, Pt4/TiO2-R（110）] were investigated via density functional theory slab calculations with Hubbard corrections（DFT＋U）. The adsorption energies under the most stable configuration of the possible species and the energy barriers of the possible elementary reactions involved in methylamine decomposition were obtained. Through systematic calculations for the reaction mechanism of methylamine decomposition on the PtVTiO2-R（110）, the most possible decomposition path is CHaNH2→CH2NH2＋H→CH2NH＋2H→CHNH＋3H→HCN＋4H→CN＋5H, which is similar to that of methylamine dissociation catalyzed by Pt（100） surface.