Synergetic Modulation of Electronic Properties of Cobalt Oxide via “Tb” Single Atom for Uphill Urea and Water Electrolysis

Abstract Exploring single‐atom (SA) catalysts in hybrid urea‐assisted water electrolysis offers a viable alternative to both Hydrogen (H 2 ) generation and polluted water treatment. However, the unfavorable electronic stabilization, low SA content, intrinsically slow kinetics, and imbalanced adsorption‐desorption steps are the bottleneck for its scale‐up implementation. Herein, a rare‐earth Terbium single atom (Tb SA ) is topologically stabilized on defect‐rich Co 3 O 4 (Tb SA @d‐Co 3 O 4 ) by Tb─O co‐ordination for urea oxidation reaction (UOR) and H 2 evolution reaction (HER). Benefitting from the strong Tb SA interaction with the d‐Co 3 O 4, the Tb SA @d‐Co 3 O 4 achieves a 10 mA cm −2 current density at 1.27 V and −35 mV for UOR and HER, respectively. Remarkably, when Tb SA @d‐Co 3 O 4 is applied as a bi‐functional catalyst in a two‐electrode system, it merely requires 1.22 V to acquire 10 mA cm −2 with excellent operational stability for 100 h. The hybrid electrolyzer can be successfully empowered by the triboelectric nanogenerator, AA battery, and solar panel with a nominal potential of 1.5 V. The mechanistic investigation predicts “Tb SA ” insertion in d‐Co 3 O 4 lowered the potential determining step, attributed to balanced reaction energetics for adsorption‐desorption of intermediates and favorable charge transfer characteristics for UOR. This work offers a new paradigm to explore the catalytic properties of rare‐earth “ f ‐block” elements to create advanced electrocatalysts via structural modulation.