Deciphering Competitive Routes for Nickel‐Based Nanoparticle Electrodeposition by an Operando Optical Monitoring

Electrodeposition of earth-abundant iron group metals such as nickel is difficult to characterize by simple electrochemical analyses since the reduction their metal salts often competes with inhibiting reactions. This makes mechanistic interpretation sometimes contradictory, preventing unambiguous predictions about nature and structure electrodeposited material. Herein, complexity Ni nanoparticles (NPs) electrodeposition on indium tin oxide (ITO) unraveled operando at a single entity NP level optical microscopy correlated ex situ SEM imaging. Our correlative approach allows differentiating dynamics formation two different populations, metallic Ni(OH)2 <25 nm limit detection, being ruled competition between Ni2+ water reduction. At this results in self-terminated growth, an information which most hidden ensemble averaged measurements.