Operando spectroscopic monitoring the dynamic transformation of CoNiMoO4 precatalyst toward efficient oxygen evolution

Electrochemical water splitting plays a pivotal role in sustainable hydrogen generation, but its efficiency remains constrained by kinetically sluggish oxygen evolution reaction (OER). Herein, CoNiMoO4 nanowires were synthesized and evaluated for potential OER application. The dynamic structural reconstruction during OER operation was monitored by combined in situ Raman and UV–vis spectroscopies, which revealed a phase evolution journey from precursor to hydroxide and finally (oxy)hydroxide at high potentials. Ni doping suppressed the complete oxidation to CoO2 phase and instead facilitated the formation of CoNiOOH intermediates as active species. Furthermore, precise modulation of the d-band center optimized the adsorption energy of oxygen intermediates, achieving enhanced catalytic activity. The findings advance the fundamental understanding of reconstruction in transition metal oxides and offer valuable insights for designing efficient OER catalysts.