Oxidized Pt clusters on a TiO2support as a robust electrocatalyst for the hydrogen evolution reaction.

Herein, we synthesized a Fe, Ni dual-metal embedded in porous nitrogen-doped carbon material to endow higher turnover frequency (TOF), lower H2O2 yield, and thus superior durability than for the single-atom catalyst for oxygen reduction in acid media. Quantitative X-ray absorption near edge structure (XANES) fitting and density functional theory (DFT) calculation were implemented to explore the active sites in the catalysts. The results suggest FeNi-N6 with type I (each metal atom coordinated with four nitrogen atoms) instead of type II configuration (each metal atom coordinated with three nitrogen atoms) dominates the catalytic activity of the noble-metal free catalyst (NMFC). Further, theoretical calculation reveals that the oxygen reduction reaction (ORR) activity trend of different moieties was FeNi-N6 (type I) > FeNi-N6 (type II) > Fe–N4 > Fe2–N6. Our research represents an important step for developing dual-metal doping NMFC for proton exchange membrane fuel cells (PEMFCs) by revealing its new structural configuration and correlation with catalytic activity.

A series of square-planar Pt(II) complexes [Pt(C^N)(O^O)] (1-5) (C^N ¼ 2-phenylpyridine, O^O denotes a series of b-diketonate ligands) is reported. Detailed studies of theoretical calculations, electrochemical and photophysical properties have shown that their excited states can be attributed to the mixing of 3 MLCT, 3 LLCT and 3 LC/ 3 ILCT transitions. For 1, the excited state is dominated by the C^N ligand. The excited states of complexes 2-5, however, are dominated by O^O ligands. Through variation of the b-diketonate ligands, the emission colors of 1-5 can be tuned from blue-green to yellow. Further investigations have revealed that the emission of 4 in the solid state can be attributed to the 3 MLCT and 3 LLL'CT transitions, which has been confirmed by X-ray diffraction studies as well as theoretical calculations. Moreover, exclusive staining of cytoplasm and low cytotoxicity have been observed for 1-4, which makes them promising candidates as phosphorescent probes for bioimaging.

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