Surface reconstruction and synergistic electrocatalysis of perovskite K-Ni-Zn-F for efficient urea-based energy conversion

Urea oxidation reaction (UOR) is hindered by poor catalytic activity, sluggish kinetics, and complex catalytic mechanism of electrocatalysts. Herein, we develop a novel perovskite K-Ni-Zn-F catalyst (KNZF-31) towards efficient UOR, showing a low potential of 1.348 V vs. RHE at 10 mA cm-2. The designed direct urea-hydrogen peroxide fuel cell (DUHPFC) provides superior open circuit voltages and power densities (0.99 V, 11.41 mW cm-2). Ex situ technology verifies amorphous electro-active/inert NiOOH/ZnO derived from surface conversion of crystalline KNZF-31, which synergistically drive the UOR. Theoretical calculation indicates that Zn-doping in KNiF3 promotes the OH- adsorption and charge transfer of Ni2+-site and formation of surface NiOOH electroactive species, which optimizes subsequent urea adsorption and charge transfer of Ni3+-site and desorption of CO2 on NiOOH/ZnO hetero-interface. This study reveals catalytic mechanism and activity origin of KNZF-31 catalyst towards UOR, offering a bright prospect for energy-sustainable developments.