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Magnetic spinel oxides have attracted extensive research interest due to their rich physics and wide range of applications. However, these materials invariably suffer suppressed magnetization, due to structural imperfections (e.g., disorder, anti‐site defects, etc.). Herein, a dramatic enhanced magnetization is obtained with an increasement of 5 µB/u.c in CoFe2O4 (CFO) through ionic liquid gating induced hydrogen doping. The intercalated hydrogen ions lead to both distinct lattice expansion of ≈0.7% and notable Fe valence state reduction through electron doping, in which ≈17% Fe3+ is reduced into Fe2+. These facts collectively trigger a site‐specific spin‐flip on tetrahedrally coordinated Co2+ sites that enhances the net ferrimagnetic moment nearly to its theoretical maximum for perfect CFO. [ABSTRACT FROM AUTHOR]

Carbon-based materials coating can serve as a protection layer to strengthen the anticorrosion and oxidation resistance ability of the catalysts. In this work, polydopamine (PDA) coated Ru-Ni(OH)2 nanosheets grown on Ni foam (Ru-Ni(OH)2/NF@PDA) was fabricated with a simple hydrothermal reaction followed by an oxidative polymerization of dopamine on the surface of Ru-Ni(OH)2/NF. Benefitting from the anticorrosion ability of PDA coating layer, the Ru-Ni(OH)2/NF@PDA displays an excellent HER activity with an overpotential of 26 mV to deliver a current density of 10 mA cm−2 and can retain 65% after 24 h, which is more stable than that of Ru-Ni(OH)2/NF. This work adopts a green and facile pathway to enhance the HER efficiency and stability through the PDA coating, which can be appropriate for other various nanomaterials. [ABSTRACT FROM AUTHOR]