Spin-polarized oxygen evolution reaction under magnetic field

Abstract

The oxygen evolution reaction (OER) is the bottleneck that limits the energy efficiency of water-splitting. The process involves four electrons’ transfer and the generation of triplet state O2 from singlet state species (OH- or H2O). Recently, explicit spin selection was described as a possible way to promote OER in alkaline conditions, but the specific spin-polarized kinetics remains unclear. Here, we report that by using ferromagnetic ordered catalysts as the spin polarizer for spin selection under a constant magnetic field, the OER can be enhanced. However, it does not applicable to non-ferromagnetic catalysts. We found that the spin polarization occurs at the first electron transfer step in OER, where coherent spin exchange happens between the ferromagnetic catalyst and the adsorbed oxygen species with fast kinetics, under the principle of spin angular momentum conservation. In the next three electron transfer steps, as the adsorbed O species adopt fixed spin direction, the OER electrons need to follow the Hund rule and Pauling exclusion principle, thus to carry out spin polarization spontaneously and finally lead to the generation of triplet state O2. Here, we showcase spin-polarized kinetics of oxygen evolution reaction, which gives references in the understanding and design of spin-dependent catalysts.

Sm-Eu Co-Doped BiFeO3 Nanoparticles With Superabsorption and Electrochemical Oxygen Evolution Reaction

“…Increasing the response efficiency of OER using a magnetic field as a new regulatory approach has recently attracted widespread attention. Ren et al showed the spin-polarized kinetics of the OER [37,38].…”

Battery‐Driven N2 Electrolysis Enabled by High‐Entropy Catalysts: From Theoretical Prediction to Prototype Model

“…In alkaline electrolyte, the following OER mechanism is usually proposed (Figure 6d and Figure S46: Supporting Information). [31,51,52]…”

“…Nevertheless, one of the problems is that most HE materials have been synthesized under extreme conditions such as high temperature (2000 to 3000 K), superfast heating/cooling rates (≈105 K s −1 ) by carbon-thermal-shock or spark ablation methods. [21,30] In this work, we are inspired by the high catalytic activity of Ni, Fe and Co for OER, [31,32] and Fe, Co, and Mn for NRR, [33][34][35] in addition to the electron densities adjustment of HE catalysts by high valence state V to change the ad/de-sorption of reactants and intermediates. [36,37] Moreover, these metal elements are highly abundant, low price and have a comparable atomic radius that makes them possible to form stable HEOs.…”

Physical Basis of Multi-Energy Coupling-Driven Water Oxidation

“…Many efforts have been made to achieve efficient energy coupling. Various energy coupling systems, such as the light coupling with electricity to create photoelectrochemical catalysis ( Fujishima and Honda, 1972 ), magnetism coupling with light or electricity to achieve spin catalysis, and the heat–electricity coupling catalysis ( Mtangi et al, 2015 ; Garcés-Pineda et al, 2019 ; Ren et al, 2021 ; Yan et al, 2021 ), were developed to drive water splitting. In these systems, the required electrical energy input was partially replaced by light, magnetism, or thermal energy.…”