Octahedral Coordinated Trivalent Cobalt Enriched Multimetal Oxygen‐Evolution Catalysts
Junsheng Chen, Hao Li, Zixun Yu, Chang Liu, Ziwen Yuan, Chaojun Wang, Shenlong Zhao, Graeme Henkelman, Shuzhou Li, Wei Li, Yuan Chen
Abstract
Abstract Octahedral coordinated trivalent cobalt cations (Co Oh 3+ ) in metal oxyhydroxides are highly active catalytic sites for the oxygen evolution reaction (OER), a critical bottleneck for efficient water splitting; however, previous synthetic methods have limited control over these sites. Herein, a scalable electrodeposition method coupled with in situ oxidation to produce amorphous Co–Fe–W trimetallic oxyhydroxides enriched with Co Oh 3+ is developed. X‐ray absorption, in operando spectroscopic analysis, and computational studies reveal that 72% of the Co atoms are present in Co Oh 3+ sites. Fe and W synergistically affect the electronic structure of Co and provide a favorable coordination environment. The Co–Fe–W oxyhydroxide exhibits superior OER catalytic performance with an impressive turnover frequency of 1.96 s −1 at an overpotential of 300 mV, a low Tafel slope of 32 mV dec −1 , and small activation energy of 53 kJ mol −1 in alkaline electrolyte. The catalyst directly deposited on Ni foams can serve as a robust OER electrode in two‐electrode water electrolyzers; they deliver a current density of 100 mA cm −2 at a small overpotential of 234 mV in alkaline electrolyte with excellent durability under 100 mA cm −2 over 120 h. These catalysts are excellent for practical water splitting applications.