Synergetic Catalysis of Magnetic Single-Atom Catalysts Confined in Graphitic-C3N4/CeO2(111) Heterojunction for CO Oxidization

Spin-polarized p-block antimony/bismuth single-atom catalysts on defect-free rutile TiO2(110) substrate for highly efficient CO oxidation

Developing high-loading spin-polarized p-block-element-based single-atom catalysts (p-SACs) upon defect-free substrates for various chemical reactions wherein spin selection matters is generally considered a formidable challenge because of the difficulty of creating high densities of underpinning stable defects and the delocalized electronic features of p-block elements. Here our first-principles calculations establish that the defect-free rutile TiO2(110) wide-bandgap semiconducting anchoring support can stabilize and localize the wavefunctions of p-block metal elements (Sb and Bi) via strong ionic bonding, forming spin-polarized p-SACs. Cooperated by the underlying d-block Ti atoms via a delicate spin donation-back-donation mechanism, the p-block single-atom reactive center Sb(Bi) exhibits excellent catalysis for spin-triplet O2 activation and CO oxidation in alignment with Wigner's spin selection rule, with a low rate-limiting reaction barrier of ∼0.6 eV. This work is crucial in establishing high-loading reactive centers of high-performance p-SACs for various important physical processes and chemical reactions, especially wherein the spin degree of freedom matters, i.e., spin catalysis.

Engineering Spin Polarization of the Surface-Adsorbed Fe Atom by Intercalating a Transition Metal Atom into the MoS2 Bilayer for Enhanced Nitrogen Reduction

The precise control of spin states in transition metal (TM)-based single-atom catalysts (SACs) is crucial for advancing the functionality of electrocatalysts, yet it presents significant scientific challenges. Using density functional theory (DFT) calculations, we propose a novel mechanism to precisely modulate the spin state of the surface-adsorbed Fe atom on the MoS2 bilayer. This is achieved by strategically intercalating a TM atom into the interlayer space of the MoS2 bilayer. Our results show that these strategically intercalated TM atoms can induce a substantial interfacial charge polarization, thereby effectively controlling the charge transfer and spin polarization on the surface Fe site. In particular, by varying the identity of the intercalated TM atoms and their vacancy filling site, a continuous modulation of the spin states of the surface Fe site from low to medium to high can be achieved, which can be accurately described using descriptors composed of readily accessible intrinsic properties of materials. Using the electrochemical dinitrogen reduction reaction (eNRR) as a prototypical reaction, we discovered a universal volcano-like relation between the tuned spin and the catalytic activity of Fe-based SACs. This finding contrasts with the linear scaling relationships commonly seen in traditional studies and offers a robust new approach to modulating the activity of SACs through interfacial engineering.

Interlayer Charge Transfer Regulates Single-Atom Catalytic Activity on Electride/Graphene 2D Heterojunctions

Single-atom catalysts with structure and activity tunability have attracted significant attention for energy and environmental applications. Herein we present a first-principles study of single-atom catalysis on two-dimensional graphene and electride heterostructures. The anion electron gas in the electride layer enables a colossal electron transfer to the graphene layer, with the degree of transfer being controllable by the selection of electride. The charge transfer tunes the d-orbital electron occupancy of a single metal atom, enhancing the catalytic activity of hydrogen evolution reactions and oxygen reduction reactions. The strong correlation between the adsorption energy E_ads and the charge variation Δq suggests that interfacial charge transfer is a critical catalytic descriptor for the heterostructure-based catalysts. The polynomial regression model proves the importance of charge transfer and accurately predicts the adsorption energy of ions and molecules. This study provides a strategy to obtain high-efficiency single-atom catalysts using two-dimensional heterostructures.