Enhanced Catalytic Ammonia Synthesis with Transformed BaO

We report that a simple mixture of BaO and CaH2 powders with ruthenium nanoparticles acts as an effective heterogeneous catalyst for low-temperature ammonia synthesis with a very small activation energy (41 kJ mol(-1)). The high catalytic performance of this material is not due to either the original CaH2 or BaO particles but to BaO transformed by reaction with CaH2. The transformed BaO contains BaH2, a stable and strong electron-donating material that facilitates a reversible hydrogen storage-release reaction and significantly enhances electron donation to Ru, which results in high catalytic performance.