Highly Efficient Photoelectrochemical Synthesis of Ammonia Using Plasmon-Enhanced Black Silicon under Ambient Conditions

Although photoelectrochemical synthesis of NH₃ is considered as an eco-friendly and sustainable process under ambient conditions, stable and highly efficient catalysts for the N₂ reduction reaction are still lacking because of the chemically inert nature of the triple bonds in elemental nitrogen and the competitive reaction of water reduction. In this paper, a photoelectrochemical N₂ reduction reaction route is proposed through combining black silicon and Ag nanoparticles using a simple deposition method. The synergetic effect of Ag nanoparticles and black Si significantly enhances the activity for the ammonia evolution reaction. The obtained Ag/bSi photocathode reaches a high Faraday efficiency of 40.6% and an NH₃ yield of 2.87 μmol h^-1 cm^-2 at -0.2 V versus the reversible hydrogen electrode in 0.1 M Na₂SO₄.