Balancing Nanoparticle Exsolution over Co-Mo Bimetallic Nitride Via Exsolution Switch for Enhanced Ammonia Decomposition.

Dai, Tianying; Qian, Shuairen; Wang, Yuhan; Yang, Jinyu; Sun, Xiaohang; Nie, Kaiqi; Su, Dong; Yan, Binhang et al. · Nano Lett · 2026

basic_science · Level V

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Abstract

Nanoparticle exsolution has emerged as an effective strategy for constructing catalytic structure, yet the precise control remains challenging. Here we introduce an "exsolution switch" strategy to regulate nanoparticle exsolution by modulating the oxidation potential of oxide hosts. Ni is incorporated into CoMoO<sub>4</sub> precursor to tune the oxidation potential and thereby control the exsolution behavior during a nitridation process. As Ni content increases, the nitride phase evolves from a homogeneous [Ni<sub><i>x</i></sub>Co<sub>1-<i>x</i></sub>]<sub>3</sub>Mo<sub>3</sub>N solid solution to a [Ni<sub><i>x</i></sub>Co<sub>1-<i>x</i></sub>]<sub>2</sub>Mo<sub>3</sub>N structure decorated with exsolved [Ni<sub><i>x</i></sub>Co<sub>1-<i>x</i></sub>]<sub>3</sub>Mo nanoparticles (<i>x</i> = 0.05-0.20). The ammonia decomposition catalytic activities exhibit a volcano-shaped dependence on Ni contents, and the solid-solution [Ni<sub>0.05</sub>Co<sub>0.95</sub>]<sub>3</sub>Mo<sub>3</sub>N catalyst without nanoparticle exsolution delivers the highest activity with 19.2 mmol<sub>H2</sub>·g<sub>cat</sub><sup>-1</sup>·min<sup>-1</sup> at 550 °C. Moderate Ni incorporation facilitates N-H bond cleavage for [Ni<sub>0.05</sub>Co<sub>0.95</sub>]<sub>3</sub>Mo<sub>3</sub>N structure, whereas excessive nanoparticle exsolution induces a shielding effect that inhibits N<sub>2</sub> desorption. These findings provide a general strategy for controlling nanoparticle exsolution via chemical potential engineering.