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.