Ac hallenging but pressing task to design and synthesize novel, efficient, and robust pH-universal hydrogen evolution reaction (HER) electrocatalysts for scalable and sustainable hydrogen production through electrochemical water splitting.H erein, we report af acile method to prepare an efficient and robust Ru-M (M = Ni, Mn, Cu) bimetal nanoparticle and carbon quantum dot hybrid (RuM/CQDs) for pH-universal HER. The RuNi/CQDs catalysts exhibit outstanding HER performance at all pH levels.The unexpected low overpotentials of 13, 58, and 18 mV shown by RuNi/ CQDs allowacurrent density of 10 mA cm À2 in 1m KOH, 0.5 m H 2 SO 4 ,a nd 1m PBS,r espectively,f or Ru loading at 5.93 mgRu cm À2 .T his performance is among the best catalytic activities reported for any platinum-free electrocatalyst. Theoretical studies reveal that Ni doping results in am oderate weakening of the hydrogen bonding energy of nearby surface Ru atoms,w hich playsac ritical role in improving the HER activity.

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The average valence, ValO, of the oxygen anions in the perovskite oxide BaTiO3, was found using O1s photoelectron spectra to be −1.55. This experimental result is close to the theoretical value for BaTiO3 (−1.63) calculated by Cohen [Nature 358, 136 (1992)] using density functional theory. Using the same approach, we obtained values of ValO for several monoxides, and investigated the dependence of ValO and the ionicity on the second ionization energy, V(M2+), of the metal cation. We found that the dependence of the ionicity on V(M2+) in this work is close to that reported by Phillips [Rev. Mod. Phys. 42, 317 (1970)]. We therefore suggest that O1s photoelectron spectrum measurements should be accepted as a general experimental method for estimating the ionicity and average valence of oxygen anions.

Sodium-ion batteries are regarded as one of the most promising energy storage systems, but the choice of anode material is still facing great challenges. Biomass carbon materials were explored for their low cost and wide range of sources. Here, a hard carbon material with a "honeycomb" structure using pine pollen (PP) as a precursor was successfully prepared and applied as an anode. The initial discharge capacity can reach 370 mA h g −1 at a current density of 0.1 A g −1 . After cycling 200 times, the reversible capacity also stabled at 203.3 mA h g −1 with the retention rate of 98%. We further studied the sodium storage mechanism by different methods, especially the Na + diffusivity coefficient (D Na + ) calculated by galvanostatic intermittent titration technique, which was more accurate. Interestingly, the trend of D Na + coincides with cyclic voltammetry curves. Carbonized PP exhibited excellent electrochemical properties because of its three-dimensional structure and larger layer spacing (∼0.41 nm), which reduces the resistance of sodium ions to intercalation and deintercalation.