Single Crystalline CoNi Selenite for Investigating a Metal Synergic Effect in Electrocatalytic Water Oxidation

Bimetallic-based materials have been considered as prominent
electrocatalysts
for water oxidation. However, ambiguous concepts about the real active
center widely exist in bimetallic electrocatalysts. Here, we prepared
CoNi selenite single crystals with nondifferential distribution of
Co and Ni metal centers. Compared with traditional solid solutions,
single crystals provide an appealing platform to investigate the metal
synergic effect in electrocatalytic water oxidation. On the basis
of detailed spectral and electrochemical studies, it has been confirmed
that Co promotes the formation of high-valent Ni species as the real
active sites for water oxidation. Since there are sustained debates
on the evolution of active sites in bimetallic materials for water
oxidation, the findings in this work are of importance to understand
the insights of water oxidation and are valuable in the rational design
of functional bimetallic electrocatalysts.