Enhancing the electroreduction of N2 and/or O2 on MoS2 using a nanoparticulate intrinsically microporous polymer (PIM-1)

Abstract

The electrochemical nitrogen reduction reaction under ambient/mild conditions offers a low-carbon alternative to the Haber–Bosch process for synthesizing NH₃, especially when coupled to solar electricity and employed on site without shippping. However, low selectivity and the competing electrocatalytic hydrogen formation presently limit practical applications. In this report, we enhance the performance of the MoS₂ electrocatalyst (a 2D material with electroactive sites for N₂ fixation) by interface engineering using a polymer of intrinsic microporosity (PIM-1) in nanoparticulate form. We report an improved selectivity and activity for both O₂ reduction to H₂O₂ and N₂ reduction to NH₃ (confirmed by ¹⁵N₂ isotope experiments). With the addition of PIM-1 nanoparticles, the NH₃ yield rate is 61.2 μg h⁻¹ mg⁻¹ (employing 0.6 mg cm⁻² MoS₂), almost twice as high as that for MoS₂ without PIM-1. The faradaic efficiency reaches 45.4% at −0.85 V vs. Ag/AgCl in 0.1 M phosphate buffer at pH 7. Experiments with direct air feed (approx. 21% O₂ and 78% N₂) demonstrate successful ammonia production even in the presence of ambient oxygen.