Chromium oxide nanoparticles in-situ immobilized onto nitrogen-doped carbon plates with boosted catalytic activity toward nitrogen reduction reaction

A chromium oxide-based nanocomposite (Cr₂O₃@NC) is designed and prepared via a simple pyrolysis route with Cr-based metal organic framework (MOF) as a template. The research results indicate that Cr₂O₃ nanoparticles have an average size of ~70 nm and are in situ formed and imbedded onto the Cr-based MOF-derived 2D N-doped carbon microplates. When employed as an inexpensive electrocatalyst for nitrogen reduction reaction (NRR) to synthesize ammonia, Cr₂O₃@NC demonstrates an improved and stable catalytic activity in comparison with bare Cr₂O₃. A large ammonia production rate of 29.42 μg mg⁻¹_cat h⁻¹ under a lower potential of −0.4 V versus reversible hydrogen electrode (RHE) can be acquired with a Faradic efficiency of 9.89% in sodium sulphate solution. Additionally, a satisfactory selectivity can also be achieved without hydrazine byproduct. The greatly promoted catalytic activity of Cr₂O₃@NC is regarded to be concerned with its desirable structures such as 2D planar topological structure with expanded active surface area, abundant catalytic sites, and effective combination with conductive carbon.