Opportunity
The development of efficient electrocatalysts for critical reactions such as the hydrogen evolution reaction (HER) is paramount for advancing clean energy technologies like water splitting. Two-dimensional transition-metal dichalcogenide nanosheets, particularly molybdenum disulfide, have emerged as promising templates for constructing hybrid nanostructures to enhance catalytic performance. However, existing methods predominantly utilize MoS₂ templates in the thermodynamically stable semiconducting 2H phase or mixed phases (e.g., 1T/2H or 1T'/2H). These mixed-phase templates contain numerous phase boundaries and defects, which severely limit the epitaxial growth and dispersion of metal catalysts. For instance, on such templates, only about 65% of synthesized platinum nanoparticles achieve epitaxial growth. Furthermore, the poor electrical conductivity of the 2H phase within these mixed structures impedes charge transfer, curtailing the further improvement of catalytic activity, especially for HER. The lack of reliable methods to prepare TMD nanosheets with high phase purity, specifically in the metallic 1T or semi-metallic 1T' phases, has made it challenging to systematically study the crystal phase's effect on templated metal growth and to fabricate hybrids with maximized performance. This creates a significant opportunity and need for a novel approach to synthesize highly pure unconventional-phase TMD nanosheets and utilize them as superior templates for creating advanced catalytic hybrids.
Technology
This patent addresses the existing challenges by disclosing a method for preparing unconventional-phase transition-metal dichalcogenide nanosheets, such as 1T'-MoS₂, with high phase purity. These nanosheets serve as ideal templates for the growth of single-atomically dispersed metals. The core innovation lies in the synthesis of hybrid materials where metal atoms like platinum, gold, nickel, iridium, silver, tin, bismuth, or copper are atomically dispersed on the surface of a uniformly crystalline TMD nanosheet, specifically in the 1T' phase. The method involves contacting the high-purity TMD nanosheet with metal precursors in the presence of a reducing agent, such as via photoreduction or chemical reduction. A key finding is that using a pure 1T'-phase template enables the stabilization of single-atomically dispersed metals at high loadings (e.g., up to 10.0 wt% for Pt) without forming nanoparticles, which is difficult to achieve on mixed-phase templates. As a proof-of-concept, the single-atomically dispersed Pt on 1T'-MoS₂ hybrid demonstrates exceptional electrocatalytic performance. Density functional theory calculations reveal that the specific adsorption sites of the single Pt atoms on the 1T'-MoS₂ lattice result in a nearly thermoneutral hydrogen adsorption free energy, which is optimal for HER catalysis.
Advantages
- Achieves single-atomic dispersion of various metals (Pt, Au, Ni, Ir, Ag, Sn, Bi, Cu) on TMD nanosheets with high loading (up to 10.0 wt%).
- Utilizes high-purity unconventional-phase (e.g., 1T') TMD nanosheets as templates, offering excellent electrical conductivity and well-defined surfaces for epitaxial growth.
- Enables precise control over the metal loading and structure, preventing nanoparticle formation at optimal loadings.
- The resulting hybrids, particularly s-Pt/1T'-MoS₂, exhibit superior electrocatalytic activity, surpassing commercial benchmarks like Pt/C.
- Demonstrates exceptional stability under high-current-density operation, crucial for industrial applications.
- Provides a versatile synthesis platform applicable in both aqueous and oil phases for various metal/TMD combinations.
Applications
- Electrocatalysis: As high-performance catalysts for the hydrogen evolution reaction (HER) in water electrolysis for green hydrogen production.
- Energy Conversion: As cathode catalysts in electrochemical cells, including proton-exchange membrane electrolyzers.
- Environmental Catalysis: For catalyzing reactions such as CO₂ reduction, nitrogen reduction, nitrite reduction, nitrate reduction, and aldehyde oxidation.
- Advanced Electrodes: Incorporated into electrodes (e.g., glassy carbon, carbon fiber paper) for various electrochemical devices.
- Materials Science: Serves as a model system for studying crystal phase effects on the growth and catalytic properties of single-atom catalysts on two-dimensional materials.
