Tao Zhang

Cu-based catalysts offer high methanol steam reforming (MSR) activity but are limited by unstable Cu+–Cu0 interconversions due to the redox and sintering labilities of Cu. Herein, we developed a universal amino-functionalized “gripper” strategy for firmly and precisely anchoring atomically dispersed metals (e.g., Cu, Co, Ni) within Beta-zeolite. Triatomic Cu oxide (Cu3Ox) sites lower the methanol dehydrogenation activation barrier, and the synergistic interplay with adjacent OH groups from silanol nests accelerates H2 evolution and the MSR reaction. Spatially decoupling Cu-mediated methanol activation from silanol-driven H2 evolution at silanol nests as proton transport channels within the confining zeolite framework also effectively protected Cu from sintering, achieving a high specific activity of 951 molH2·molCu–1·h–1 and over 600 h of stability under continuous regeneration. This work provides a universal strategy for synthesizing atomically dispersed metal catalysts and a new design principle for maintaining the Cu structure during MSR.

Highly selective oxidation of methane to liquid oxygenates under mild conditions remains challenging because of the difficulty in controlling overoxidation at highly reactive sites. Here, we demonstrate remote control of single-atom Cu reactivity through outer-shell coordination engineering in Zr-based metal-organic frameworks (MOFs). By anchoring Cu ₁ to Zr-oxo nodes in UiO-66-X (X = -NO ₂ , -H, and -CH ₃ ), remote X-BDC ligands systematically modulate the electronic properties of Cu ₁ sites and the catalytic microenvironment. In situ characterization combined with ab initio molecular dynamics in an explicitly solvated aqueous environment reveals a dynamic outer-shell-to-inner-shell regulation that reshapes the active structure and reactive oxygen species around Cu ₁ sites, thereby facilitating CH ₄ activation. In particular, the electron-withdrawing NO ₂ -BDC ligand creates electron-deficient Cu ₁ - ^• OH* sites, while adsorbed water further regulates active-site conformation. Consequently, Cu ₁ /U6-NO ₂ achieves a turnover frequency of 322.4 h ⁻¹ with nearly 100% oxygenate selectivity under mild conditions, establishing a general strategy for overcoming activity-selectivity trade-offs in methane conversion.

The strain at the surface of a catalyst is a critical factor that alters the bonding characteristics of active sites and thereby modifies catalytic activity and stability. In situ environmental transmission electron microscopy (ETEM) provides an unprecedented opportunity to unravel atomic-scale strain distribution in individual catalyst particles. However, it remains a significant challenge to determine the evolving strain with picometer precision from the large ETEM data sets. In this work, we develop an atomic column identification framework based on denoising and iterative refinement, enabling accurate localization of atomic column positions in TEM images. Building on high-precision identified coordinates, we were able to further establish an atomic-scale strain mapping method that quantifies local strain at the individual atomic column. This approach unveils distinct strain patterns induced by surface defects in TiO2 nanocrystals and MoS2 monolayers, as well as anisotropic strain associated with particle size effects in RuO2/TiO2 catalysts. Our work enables direct visualization and quantitative analysis of strain in individual catalyst particles at the atomic-scale, providing a robust framework for correlating local structural distortions with catalytic properties and offering new insights into the rational design of supported metal catalysts.

The influence of trace oxidizing cofeeds on reshaping the catalytic microenvironment under reducing conditions remains largely unexplored. Here, we show that cofeeding trace CO2 or H2O with C3H8 constructs dual-atom sites for propane dehydrogenation, circumventing their reduction-induced aggregation that plagues such catalysts. The oxidation of In species gives rise to In3+ single atoms anchored by Si defects and then Rh3+ single atoms linked by framework oxygen, which together assemble diatomic sites with the structure of Z2[RhH] in a RhIn/S-1 catalyst. The catalyst with Rh loadings of merely 0.02 wt % exhibits an unprecedented performance with ∼75% C3H6 yield (near equilibrium), a space-time yield of 1729.1 molC3H6 gRh–1 h–1, and stability for 1000 h on-stream without regeneration, outperforming most of the state-of-the-art catalysts. Single-atom Rh3+ synergizes with atomically dispersed In-coordinated framework oxygen to facilitate C–H cleavage. This work reveals the hitherto unrecognized role of trace oxidizing cofeeds under reducing conditions and offers a promising strategy of oxidation-enabled assembly to design active sites extending to other catalytic processes.

Engineering the electronic and spin states of active centers for promoted oxygenate production from methane remains a fundamental challenge in catalysis. Herein, we demonstrate that spin crossover of Fe1 single-atoms from high spin (HS) to low spin (LS) could boost the oxygenate yield by 5.3-fold. The spin transition is realized by coordinating Fe1 sites with strong-field ligand carbon monoxide (CO). Compared with traditional L-FeHS-O (L = H2O) motifs, low-spin L-FeLS-O (L = CO) with CO coordination introduces unoccupied O 2p states near the Fermi level and increases electron density on the oxygen center. The resulting enhancement in electrophilicity of the oxo center facilitates hydrogen abstraction from methane, lowering the C−H activation barrier from 1.26 eV to 0.65 eV. Consequently, an oxygenate productivity of 1615.3 mmol gFe−1 h−1 with ∼100% selectivity is achieved at 30 °C. The strategy of spin regulation paves an avenue for designing prospective single-atom catalysts toward efficient methane valorization.

Carboxylic acids are ubiquitous structural motifs in bioactive molecules, making their site-selective deuteration a powerful tool for probing biochemical mechanisms and improving the pharmacokinetic properties of drug molecules. Late-stage H/D exchange offers superiority over de novo synthesis from deuterated precursors, but remains challenging. Here, we report, to our knowledge, the first α-site-selective deuteration method that is compatible with both free amino acids and general (non-amino-acid) carboxylic acids enabled by a regenerable Pd₁/CeO_x single-atom catalyst. Mechanistic studies reveal that, unlike previously established mechanisms, the reaction proceeds via a carboxyl-directed pathway, relying on synergistic interactions between Pd single atoms and the CeO_x support: the CeO_x surface anchors the carboxylate, while the Pd mediates α-C − H bond activation. This method features a broad substrate scope and excellent site-selectivity, underscoring its generality and establishing a versatile platform for late-stage isotopic labeling of pharmaceuticals and other complex molecules.