Tuning the Electronic Spin State of Catalysts by Strain Control for Highly Efficient Water Electrolysis

Abstract

The electronic configuration is crucial in governing the binding strength of intermediates with catalysts, yet it is still challenging to control the catalysts' surface electronic spin state. Here, it is demonstrated that through surface metal–organic framework transformation followed by acid etching, the electronic spin state of surface Co3+ ions on spinel Co3O4 can be transformed from t2g6 to the high electronic spin state of t2g4eg2 by expanding the surface lattice constant, which significantly enhances the overlap of the eg orbital of cobalt with the oxygen adsorbates, and greatly improves the intermediates adsorption and thus the oxygen evolution reaction activity. The high electronic spin rich Co3O4 electrode exhibits an anodic current density of 10 mA cm−2 at an overpotential of 280 mV. The finding offers a rational design strategy to manipulate the electronic spin state of catalyst and the hybridization of molecular orbitals in water electrolysis.

Redox‐Inert Fe3+ Ions in Octahedral Sites of Co‐Fe Spinel Oxides with Enhanced Oxygen Catalytic Activity for Rechargeable Zinc–Air Batteries

“…Accordingly,s pinel Co 3 O 4 has been regarded as apromising OER/ORR catalyst, especially since the two types of cobalt ions can induce different functions.For OER, Co 2+ Td serves as the active site to form the m-OOH moieties in the catalytic cycle. [8] ForO RR, CoO 6 combines with O 2 to form an oxygen intermediate on the catalyst surface;the 3d-e g filling of Co 3+ Oct in this process can optimize the absorption strength of the reactive oxygen intermediates. [9,10] In the ordinary form of Co 3 O 4 ,t he overly strong interaction between the oxygen intermediates and the lowspin Co 3+ Oct leads to sluggish ORR/OER dynamics.…”

Redox‐Inert Fe3+ Ions in Octahedral Sites of Co‐Fe Spinel Oxides with Enhanced Oxygen Catalytic Activity for Rechargeable Zinc–Air Batteries

“…Accordingly, spinel Co 3 O 4 has been regarded as a promising OER/ORR catalyst, especially since the two types of cobalt ions can induce different functions. For OER, Co 2+ Td serves as the active site to form the μ‐OOH moieties in the catalytic cycle . For ORR, CoO 6 combines with O 2 to form an oxygen intermediate on the catalyst surface; the 3d‐e g filling of Co 3+ Oct in this process can optimize the absorption strength of the reactive oxygen intermediates .…”

NiFe Hydroxide Lattice Tensile Strain: Enhancement of Adsorption of Oxygenated Intermediates for Efficient Water Oxidation Catalysis

“…Thec hange in adsorption energies for oxygenated intermediates on ball-milled NiFe-LDH is anticipated to influence the catalytic activity. [21] We then carried out electrochemical characterizations to examine the OER activities of various NiFe-LDH as shown in Figure 2a nd the Supporting Information, Figures S9-S11. Figure 2A and the Supporting Information, Figure S10A compare the iR-and BET-corrected CV curves of NiFe-LDH before and after different durations of ball-milling treatment.…”