Rh, Co, and N-doped titanium mesh-based carbon nanosheet arrays for enhanced nitrite reduction reaction and ammonia generation

The electrocatalytic transformation of nitrite pollutants into valuable ammonia is crucial for the nitrogen cycle. However, the complex multi-reaction process necessitates the development of highly efficient and selective electrocatalysts. This study focuses on the creation of Rh-doped Co@NC anchored on a titanium mesh as an electrocatalyst to enhance the electrocatalytic nitrite reduction reaction (eNO2RR) for NH3 synthesis. By doping a trace amount of Rh within zeolitic imidazolate framework-67 nanosheets and subsequently pyrolyzing the material, uniformly distributed Rh and Co nanoparticles are anchored onto N-functionalized porous carbon nanosheet arrays. Consequently, the three-dimensional electrode enhances mass and electron transfer while providing abundant surface-exposed active sites for NH3 generation through eNO2RR. The Rh0.6 wt%–Co@NC/TM electrocatalyst, with a minimal Rh loading of 0.6 wt%, exhibits the highest Faradaic efficiency of 98.8 ± 0.7 % at −0.3 V, along with an NH3 yield of 1777.1 ± 7.0 μmol h−1 cm−2 at −0.7 V. Additionally, the electrocatalyst demonstrates exceptional durability over 20 consecutive cycles and remarkable environmental adaptability. Extensive experimental studies reveal that the superior performance of Rh0.6 wt%–Co@NC/TM arises from the synergistic catalysis between Co and Rh, which enhances NO2– adsorption and the production of active hydrogen for eNO2RR to NH3 synthesis. This research highlights that Rh incorporation facilitates the kinetics of eNO2RR and offers valuable insights for the development of efficient electrocatalysts towards NH3 synthesis.