Breakthrough Method Enables Unprecedented Control Over Dual-Atom Catalyst Synthesis

Revolutionary Catalyst Synthesis Method

Scientists have reportedly developed a groundbreaking ligand-restricted synthesis strategy that enables unprecedented control over dual-atom catalyst manufacturing, according to research published in Nature Materials. The new approach allows researchers to create highly paired homo- and heteronuclear dual-atom catalysts (DACs) with controllable atomic distances engineered through coordinating diamine ligands with metal precursors on two-dimensional graphitic carbon nitride supports.

Revolutionary Catalyst Synthesis Method
Exceptional Pairing Ratios Achieved
Dramatic Performance Improvements
Mechanism and Characterization
Critical Factors for Successful Synthesis
Spectroscopic Validation

Exceptional Pairing Ratios Achieved

The engineered DACs have achieved a pairing ratio exceeding 82%, which sources indicate markedly surpasses previously reported values. Researchers demonstrated the ability to control atomic distances from 0.81 to 0.22 nanometers by varying the chain length of diamine ligands – a capability analysts suggest has not been realized by existing methods. The report states that this level of precision in atomic-level manufacturing represents a significant advancement in catalyst design.

Dramatic Performance Improvements

As proof of concept, the paired atom Pt1-Au1/g-C3N4-HA DACs exhibited considerably higher catalytic activity (744 mg h-1 mgmetal-1) than the unpaired counterpart (255 mg h-1 mgmetal-1) in nitrate reduction to ammonia. The research team claims their strategy can be used to prepare various homo- and heteronuclear platinum- and gold-based DACs, potentially opening new avenues for catalyst development across multiple industrial applications.

Mechanism and Characterization

According to the detailed methodology, linear 1,6-hexanediamine (HA) was used as the ligand with two amine groups to coordinate the two metal precursors. Two-dimensional graphitic carbon nitride was selected as the support due to its abundant nitrogen sites and defects. Analysis reportedly showed that for homonuclear Pt/g-CN-HA DACs, one HA molecule could restrict two platinum atoms by forming two Pt-amine complex end groups via dechlorination.

Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy characterization revealed numerous bright dots representing platinum atoms, with many paired platinum atoms easily distinguished. Quantitative analysis indicated an exceptional Pt-Pt pairing ratio of 88% in Pt/g-CN-HA, while heteronuclear Pt-Au/g-CN-HA achieved 82% pairing ratio based on counting over 2,400 atoms.

Critical Factors for Successful Synthesis

The research identifies several critical parameters for successful atomic dispersion:

Synthesis temperature: Lower temperatures favor atomic dispersion, with optimal results below 400°C
Metal type: Different metals exhibit varying cohesive energies and metal-support binding energies
Support material: Two-dimensional materials prove more effective for anchoring metal atomic pairs

Density functional theory calculations reportedly revealed that gold exhibits higher cohesive energy than platinum (-5.90 eV versus -5.59 eV) but weaker binding to graphitic carbon nitride (-1.10 eV versus -3.30 eV), explaining why gold tends to aggregate more readily than platinum under identical conditions.

Spectroscopic Validation

Multiple spectroscopic techniques were employed to validate the atomic dispersion. X-ray absorption near-edge spectroscopy analyses showed the white-line intensity of Pt/g-CN-HA between metallic platinum foil and platinum oxide, indicating an oxidation state of +1.8 for the dual-platinum centers. Extended X-ray fine-structure spectroscopy spectra identified a dominant peak at 1.60 Å assigned to Pt-N coordination, while the absence of the Pt-Pt characteristic peak at 2.60 Å was corroborated by wavelet transform analysis.

Researchers suggest this work not only presents a synthesis strategy for atomic-level manufacturing of complex catalysts but also provides valuable insights into nanoscale reactions in heterogeneous catalysis. The ability to precisely control atomic pairing and distances could potentially revolutionize catalyst design for various industrial processes, though analysts note further research is needed to scale the technology for commercial applications.