Ti3C2Tx MXenes and Mn3O4 nanoparticles synergistically promote the electrochemical synthesis of ammonia under ambient conditions

Abstract

Ammonia serves as a hydrogen energy carrier and a renewable, zero-carbon fuel alternative that is safely transportable. The electrochemical catalytic reduction of N₂ to NH₃ in aqueous electrolytes at ambient temperature and pressure (eNRR) using electricity generated from renewable energy sources such as solar and wind power can provide an environmentally friendly approach. To effectively suppress the occurrence of hydrogen evolution side reactions, it is necessary to design and synthesize catalysts with high selectivity for N₂ adsorption. Owing to the ability of transition metals with unoccupied d orbitals to significantly promote the adsorption of N₂ molecules and the activation of inert bonds, researchers have explored manganese-oxide catalysts through both experimental and theoretical studies. However, manganese oxides are semiconductor materials with poor conductivity. To solve this problem, the Ti₃C₂T_x MXene material can be introduced as a carrier for manganese oxide particles. In this study, the Ti₃C₂@Mn₃O₄ composite was used as an electrocatalyst for ammonia synthesis under ambient conditions using a simple method. Benefiting from the synergistic catalytic effect of MXene and Mn₃O₄, the composite exhibits excellent catalytic performance for ammonia synthesis, with an NH₃ yield rate of 53.7 μg h⁻¹ mg_cat.⁻¹ and satisfactory FE of 10.4% at −0.6 V (vs. RHE) under ambient conditions. The composite catalyst exhibits excellent stability, durability, and selectivity, with outstanding synergistic effects, surpassing most reported NRR electrocatalysts. This simple and versatile strategy may offer researchers inspiration for rationally designing highly efficient NRR electrocatalysts.