The slow kinetics of water oxidation greatly jeopardizes the efficiency of water electrolysis for H production. Developing highly active water oxidation electrodes with affordable fabrication costs is thus of great importance. Herein, a Ni Fe surface species on Ni metal substrate was generated by electrochemical modification of Ni in a ferrous solution by a fast, simple, and cost-effective procedure. In the prepared Ni Fe catalyst film, Fe was incorporated uniformly through controlled oxidation of Fe cations on the electrode surface. The catalytically active Ni originated from the Ni foam substrate, which ensured the close contact between the catalyst and the support toward improved charge-transfer efficiency. The as-prepared electrode exhibited high activity and long-term stability for electrocatalytic water oxidation. The overpotentials required to reach water oxidation current densities of 50, 100, and 500 mA cm are 276, 290, and 329 mV, respectively.

Water-soluble copper(II) complexes of the dianionic tridentate pincer ligand N,N'-2,6-dimethylphenyl-2,6-pyridinedicarboxamidate (L) are catalysts for water oxidation. In [L-Cu-DMF] (1, DMF = dimethylformamide) and [L-Cu-OAc] (2, OAc = acetate), ligand L binds Cu through three N atoms, which define an equatorial plane. The fourth coordination site of the equatorial plane is occupied by DMF in 1 and by OAc in 2. These two complexes can electrocatalyze water oxidation to evolve O in 0.1 M pH 10 carbonate buffer. Spectroscopic, titration, and crystallographic studies show that both 1 and 2 undergo ligand exchange when they are dissolved in carbonate buffer to give [L-Cu-COH] (3). Complex 3 has a similar structure as those of 1 and 2 except for having a carbonate group at the fourth equatorial position. A catalytic cycle for water oxidation by 3 is proposed based on experimental and theoretical results. The two-electron oxidized form of 3 is the catalytically active species for water oxidation. Importantly, for these two oxidation events, the calculated potential values of E = 1.01 and 1.59 V vs normal hydrogen electrode (NHE) agree well with the experimental values of E = 0.93 and 1.51 V vs NHE in pH 10 carbonate buffer. The potential difference between the two oxidation events is 0.58 V for both experimental and calculated results. With computational evidence, this Cu-bound carbonate group may act as a proton shuttle to remove protons for water activation, a key role resembling intramolecular bases as reported previously.

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An aqueous emulsion polymerization self‐assembly approach is demonstrated for the first time to synthesize ultrahigh nitrogen containing mesoporous polymer nanospheres, using melamine‐formaldehyde resin oligomers as precursors. In the synthesis, change from alkaline to acidic conditions is critical for the formation of monodisperse mesostructured polymer nanospheres. Owing to unique structure of triazine stabilized in the covalent polymeric networks during the pyrolysis process, the derived mesoporous carbon nanospheres possess an ultrahigh nitrogen content (up to 15.6 wt%) even after pyrolysis at 800 °C, which is the highest nitrogen content among mesoporous carbon nanospheres. Furthermore, these monodisperse mesoporous carbon nanospheres possess a high surface area (≈883 m2 g−1) and large pore size (≈8.1 nm). As an anode for sodium‐ion batteries, the ultrahigh nitrogen‐containing mesoporous carbon nanospheres exhibit superior rate capability (117 mAh g−1 at a high current density of 3 A g−1) and high reversible capacity (373 mAh g−1 at 0.06 A g−1), indicating a promising material for energy storage.