A two-dimensional MXene-supported metal–organic framework for highly selective ambient electrocatalytic nitrogen reduction

The conversion of nitrogen into ammonia is crucial for human activities. The electrochemical synthesis of ammonia from nitrogen and water is a green process with great application prospects; to this end, much effort has been made to improve the catalytic activity and selectivity. Here, a Co-based metal-organic framework (MOF), that is, zeolitic imidazolate framework-67 (ZIF-67), supported on a Ti₃C₂ MXene (defined as ZIF-67@Ti₃C₂) was prepared via in situ growth. Due to the high porosity and large active surface area of the MOF and the superior conductivity of the Ti₃C₂ MXene, the composite could efficiently synthesize ammonia electrochemically. In particular, the prepared ZIF-67@Ti₃C₂ catalyst exhibited an excellent NH₃ yield (6.52 μmol h^-1 cm^-2), significantly higher than those achieved by Ti₃C₂ and ZIF-67 (2.77 and 1.61 μmol h^-1 cm^-2, respectively) alone, and good Faraday efficiency (20.2%) at -0.4 V (vs. the reversible hydrogen electrode). This study not only expands the application of the MXene family in the electrochemical nitrogen reduction reaction but also provides ideas for the development of high-performance electrocatalysts for NRR.