Interfacial Electronic Coupling and Surface Reconstruction in Co(OH) 2 @NiFe‐btz for Durable Alkaline Oxygen Evolution
Li Jing, Zihui Liang, Shuang Guo, Ping Wang, Xiaotian YangABSTRACT
Coupling metal hydroxides with coordination frameworks offers a route to active and durable oxygen evolution reaction (OER) electrodes. A binder‐free Co(OH) 2 @NiFe‐btz heterostructure, where btz is 1,4‐bis(4H‐1,2,4‐triazol‐4‐yl)benzene, is constructed on nickel foam through solvothermal growth followed by electrodeposition. Microscopy reveals close contact between Co(OH) 2 nanosheets and the framework. Ultraviolet and x‐ray photoelectron spectroscopy indicate interfacial charge redistribution consistent with the work‐function difference, while electron paramagnetic resonance detects paramagnetic states. In 1.0 M KOH, the electrode delivers 10 mA cm −2 at an overpotential of 219 mV, exhibits a Tafel slope of 57.1 mV dec −1 , and operates at 100 mA cm −2 for 1000 h. Operando Raman spectroscopy reveals potential‐dependent formation of a cobalt/nickel oxyhydroxide‐like surface phase. Isotope‐labeling mass spectrometry and infrared spectroscopy of the target electrode, considered alongside electrochemical probes, are consistent with possible lattice‐oxygen participation, without establishing its fraction of the oxygen‐evolution flux. Density functional theory calculations on idealized precursor structures show that interfacial coupling and an imposed oxygen vacancy modify metal d and O 2p states and reduce the largest uphill free‐energy step in a candidate lattice‐oxygen pathway. Together, these results connect framework‐hydroxide coupling with enhanced electrode performance and the evolution of its catalytic surface.