Lattice oxygen activation enabled by high-valence metal sites for enhanced water oxidation

Abstract

Anodic oxygen evolution reaction (OER) is recognized as kinetic bottleneck in water electrolysis. Transition metal sites with high valence states can accelerate the reaction kinetics to offer highly intrinsic activity, but suffer from thermodynamic formation barrier. Here, we show subtle engineering of highly oxidized Ni 4+ species in surface reconstructed (oxy) hydroxides on multicomponent FeCoCrNi alloy film through interatomically electronic interplay. Our spectroscopic investigations with theoretical studies uncover that Fe component enables the formation of Ni 4+ species, which is energetically favored by the multistep evolution of Ni 2+ →Ni 3+ →Ni 4+. The dynamically constructed Ni 4+ species drives holes into oxygen ligands to facilitate intramolecular oxygen coupling, triggering lattice oxygen activation to form Fe-Ni dual-sites as ultimate catalytic center with highly intrinsic activity. As a result, the surface reconstructed FeCoCrNi OER catalyst delivers outstanding mass activity and turnover frequency of 3601 A g metal −1 and 0.483 s −1 at an overpotential of 300 mV in alkaline electrolyte, respectively.

Selectively Upgrading Lignin Derivatives to Carboxylates through Electrochemical Oxidative C(OH)−C Bond Cleavage by a Mn‐Doped Cobalt Oxyhydroxide Catalyst

“…Significantly, electrophilic oxygen species (i.e. OH*, O*, OOH*) have been identified on the anodic catalysts surface during alkaline OER process by experiments and/or theoretical calculations [9c, 12, 16, 18] . It is well demonstrated that the rate‐determining‐step over Co‐based hydroxides or oxyhydroxides is the deprotonation of adsorbed OH* to O* (step ii ), [19] being consistent with our density functional theory (DFT) calculations over MnCoOOH catalyst (Figure 3 d, left circle and Figures S19,20).…”

High Density and Unit Activity Integrated in Amorphous Catalysts for Electrochemical Water Splitting

“…Reproduced under the terms of a Creative Commons Attribution 4.0 International License. [ 77 ] Copyright 2020, The Authors, published by Springer Nature.…”

“…The Fermi level and metal d‐band are found to decrease and penetrate the p band of the oxygen ligand, which can enhance the covalency of the metal–oxygen (MO) bond, thereby triggering the redox activity of the lattice oxygen and directly participating in OER process, namely, LOM. [ 4 ] Chai [ 77 ] and co‐workers drawn conclusion that the formation of high‐valence Ni 4+ sites can activate lattice oxygen ligands with electron holes, which is the pivotal reason for the high catalytic activity according to the downshift of Fermi level and metal d‐band in Figure 5d,e.…”

Reconstructed Water Oxidation Electrocatalysts: The Impact of Surface Dynamics on Intrinsic Activities

“…[ 23,43,45 ] Also, the reconstruction process changes the surface of electrocatalysts reversibly or irreversibly depending on their structural features. [ 48–58 ] For example, the Co 3 O 4 electrocatalyst self‐reconstructed into amorphous CoO x (OH) y (di‐ u ‐oxobridged Co 3+/4+ ) under OER potential region can be reverted to the original structure when returning the potential to the non‐OER region . [ 59 ] Conversely, noble metal‐based electrocatalysts, transition metal‐based oxides and nonoxides (e.g., chalcogenides, pnictides, carbides, etc.)…”