# Design of Alkaline Earth‐Doped Co/MgO Catalysts for Ammonia Decomposition

## TL;DR

Scientists designed a new catalyst using cobalt and magnesium oxide doped with barium to efficiently produce hydrogen from ammonia decomposition.

## Contribution

The study reveals a unique Co-BaO core-shell structure formed by alkaline earth doping, enhancing ammonia decomposition efficiency.

## Key findings

- Co/Ba0.01Mg0.99O achieves 94.4% ammonia conversion and 3.79 mol gcat⁻¹ h⁻¹ hydrogen production at 500°C.
- The Co-BaO core-shell structure facilitates efficient electron donation to Co nanoparticles, promoting N2 formation.
- Alkaline earth metal doping weakens the adsorption of strongly bound species, improving catalytic performance.

## Abstract

Hydrogen is expected to be used as a fuel additive to ammonia, a non‐flammable and carbon‐free fuel, to improve combustion efficiency. However, the design strategies for developing highly active, nonprecious metal catalysts for ammonia decomposition are not yet well understood. Here, we show that Co/Ba0.01Mg0.99O exhibits high activity, with an ammonia conversion of 94.4% and a hydrogen production rate of 3.79 mol gcat
−1 h−1 at 500°C with a WHSV of 60,000 mL gcat
−1 h−1. Comparison of the dopant effects of alkaline earth metal elements elucidates that the high activity of Co/Ba0.01Mg0.99O is ascribed to the formation of a specific Co‐BaO core–shell‐like structure, with highly basic BaO nanoparticles covering the Co particles. The core–shell‐like structures were not formed with other alkaline earth elements. Such features facilitate efficient electron donation to Co nanoparticles, promoting N2 formation. Furthermore, kinetic analysis indicated that doping of alkaline earth metals weakens the adsorption of strongly bound species. Our findings will contribute to the development of cost‐effective supported metal catalysts for hydrogen production through ammonia decomposition, leading to the realization of a carbon‐neutral society in which ammonia plays a key role.

Co/Ba0.01Mg0.99O exhibits high catalytic activity for H2 production via NH3 decomposition due to its Co‐BaO core–shell‐like structure, which does not occur with other alkaline earth elements. This architecture forms through reduction at 700°C, where MgO sintering induces Co nanoparticle migration. Migrating Co particles scrape melted Ba(OH)2 from the MgO surface, leading to BaO deposition on Co surfaces.© 2026 WILEY‐VCH GmbH