Orbital hybridizations in single-atom catalysts for electrocatalysis
Orbital hybridizations in single-atom catalysts for electrocatalysis
Orbital Hybridizations in Single-Atom Catalysts for Electrocatalysis
Orbital hybridization plays a central role in tuning the electronic properties and catalytic activities of single-atom catalysts (SACs) used in electrocatalysis. These catalysts feature isolated metal atoms anchored on a conductive support, offering maximum atomic efficiency and unique reaction pathways. The interaction between the metal atom’s d-orbitals and the surrounding ligands—commonly nitrogen, oxygen, or carbon—results in tailored orbital hybridizations that govern the charge distribution, adsorption energy, and transition states of electrochemical reactions such as the hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and CO₂ reduction reaction (CO₂RR).
By engineering the orbital hybridization between metal centers and their coordination environment, researchers can tune the electronic density of states, which influences the binding strength of key intermediates. For instance, the d-band center theory helps explain how hybrid orbitals shift electronic energy levels, thus affecting catalytic turnover. Furthermore, computational studies using density functional theory (DFT) often reveal how s, p, and d orbital interactions influence selectivity and activity, providing guidance for the rational design of advanced electrocatalysts.
In SACs, the orbital overlap between metal and non-metal atoms (e.g., M–N₄ or M–C₄ motifs) allows fine-tuning of active sites for specific reactions. Hybridization also affects spin polarization, charge transfer, and stability—factors that are crucial for long-term catalytic performance in harsh electrochemical environments.
Researchers exploring orbital hybridization in SACs often rely on advanced spectroscopic techniques such as X-ray absorption spectroscopy (XAS) and electron energy loss spectroscopy (EELS) to experimentally validate orbital configurations and bonding environments. These insights pave the way for developing next-generation SACs with optimized reaction kinetics and minimal energy barriers.
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