Research Projects

The oxygen electrocatalysis (OxEcat) refer to oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), plays pivotal role in various energy storage and conversion devices that include water electrolyzers, fuel cells, metal-air batteries, CO2-electrolyzers etc. The sluggish kinetics of OER and ORR are often the bottlenecks that limit the overall efficiency of these devices. The OER/ORR is a complex 4e--4H+ process involving multiple intermediates such as *OH, *O and *OOH. Majority of earlier studies involve the developing of catalysts based on thermodynamic considerations, which led to volcano plots that depicts the dependence of reaction rate (or exchange current density) on the free energy of adsorption of reactants/intermediates for various electrocatalysts. The catalysts present at the apex of the plot are considered as the best catalyst. However, the studies do not invoke the role of the electrons’ spin on the kinetics of OER/ORR. The present proposal focus on the utilization of the electrons’ spin effects in designing OxEcats, a relatively less explored territory, to achieve improved performance. According to quantum mechanics, the change in the orientation of electron’s spin and orbital occupancy may lead to the redistribution of electronic structures due to changes in exchange interactions. This may affect the catalyst-reactant/intermediate interactions, which results in different binding affinities with intermediates depending on the spin state and thus affect the activity. Thus it is essential to invoke spin effects especially for OER because the ground state of molecular oxygen exists as a triplet instead of singlet, indicating that the spin constraints play a determining role. The formation of molecular oxygen from oxygen atoms involves the formation of energetic singlet state in the absence of spin restrictions, and thus warrants high overpotential for OER. In addition, high selectivity can be achieved by the spin constraints as it avoids the formation of unwanted kinetically favored H2O2 during OER/ORR. Unlike the majority of the research that involved in the development of OxEcat, the present proposed research utilizes the electrons’ spin effects to develop OxEcat with improved activity and selectivity towards OER/ORR. This is achieved using chiral electrocatalysts as they can act as spin filters even at room temperature. In other words, the electron transfer through the chiral system is spin selective. This means that the type of spin being transferred through chiral material depends on the handedness of the material and direction of charge transfer and the phenomenon is termed as Chirality Induced Spin Selectivity (CISS) effect. Though there exist few reports in this direction, but the field is still in the exploratory stage. The detailed understanding of chirality enhanced OER/ORR is still lacking. Operando studies are required to further understand and establish the correlation between chirality and OxEcat activity. Majority of the reported works are limited to half-cell (3-electrode) studies and the demonstration of the ability of chiral electrodes in real devices are needed to be explored. In this direction, the proposed research focus on exploring some of these issues by rational designing of chiral materials by leveraging their intrinsic activity for OER/ORR. The effect of chiral molecule on optical activity of chosen chiral materials and the correlation between optical activity and OxEcat activity will be studied. Further, the applicability of developed chiral OxEcats in energy devices such as zinc-air batteries and water electrolyzers will be studied and the advantages of chirality-induced spin selectively of chiral materials in achieving 5-10% improved efficiency as compared to the achiral counterparts will be demonstrated. The studies will pave ways to explore other multi-electron reactions such as CO2 reduction reaction, nitrogen reduction reaction etc.