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Balancing Nanoparticle Exsolution over Co-Mo Bimetallic Nitride Via Exsolution Switch for Enhanced Ammonia
Tianying Dai1, Shuairen Qian1, Yuhan Wang2
1Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
Nano Letters
|May 27, 2026
Summary
Researchers developed an "exsolution switch" strategy to control nanoparticle exsolution in catalysts. This method precisely tunes catalyst performance by adjusting nickel content in cobalt molybdate hosts for ammonia decomposition.
Area of Science:
- Materials Science
- Catalysis
- Nanotechnology
Background:
- Nanoparticle exsolution is a key method for creating advanced catalytic structures.
- Precise control over nanoparticle exsolution in catalytic materials remains a significant challenge.
- Oxidation potential of oxide hosts is a critical factor influencing nanoparticle exsolution.
Purpose of the Study:
- To introduce and validate an "exsolution switch" strategy for regulating nanoparticle exsolution.
- To control nanoparticle exsolution by modulating the oxidation potential of oxide hosts through nickel incorporation.
- To investigate the effect of nickel content on the structure and catalytic activity of cobalt molybdate nitride catalysts.
Main Methods:
- Incorporation of nickel (Ni) into cobalt molybdate (CoMoO4) precursors to tune oxidation potential.
- Nitridation process to induce and control nanoparticle exsolution.
- Characterization of nitride phase evolution and nanoparticle decoration using varying Ni content (x = 0.05-0.20).
- Evaluation of ammonia decomposition catalytic activity at 550 °C.
Main Results:
- Nitride phase evolved from a homogeneous [Ni_xCo_{1-x}]_3Mo_3N solid solution to a [Ni_xCo_{1-x}]_2Mo_3N structure with exsolved nanoparticles as Ni content increased.
- Ammonia decomposition activity showed a volcano-shaped dependence on Ni content.
- The solid-solution [Ni_0.05Co_0.95]_3Mo_3N catalyst, without nanoparticle exsolution, exhibited the highest activity (19.2 mmol_H2·g_cat^{-1}·min^{-1}).
- Excessive nanoparticle exsolution led to a shielding effect, inhibiting N2 desorption.
Conclusions:
- The "exsolution switch" strategy effectively controls nanoparticle exsolution by engineering chemical potential.
- Moderate nickel incorporation enhances N-H bond cleavage, while excessive exsolution hinders catalytic performance.
- This provides a generalizable approach for designing catalysts with tailored nanoparticle exsolution properties.
