Efficient Electrocatalytic Nitrogen Reduction to Ammonia with Electrospun Hierarchical Carbon Nanofiber/TiO₂@CoS Heterostructures

As a sustainable alternative technology to the cost- and energy-intensive Haber-Bosch method, electrochemical nitrogen (N₂) reduction offers direct conversion of N₂ to NH₃ under ambient conditions. Direct use of noble metals or non-noble metals as electrocatalytic materials results in unsatisfactory electrocatalytic properties because of their low electrical conductivity and stability. Herein, three-dimensional flexible carbon nanofiber (CNF/TiO₂@CoS) nanostructures were prepared on the surface of CNF by using electrospinning, a hydrothermal method, and in situ growth. We investigated the behavior of CNFs/TiO₂@CoS as an electrocatalytic material in 0.1 M sodium sulfate. The highest ammonia yield of the material was 4.61 × 10^-11 mol s^-1 cm^-2 at -0.45 V vs. RHE, and the highest Faraday efficiency, as well as superior long-term durability, was 8.3% at -0.45 V vs. RHE. This study demonstrates the potential of firecracker-shaped nanofiber templates for loading varied noble metals or non-noble metals as a novel development of hybrid composites for electrocatalytic nitrogen reduction.