Free-Standing Nanoarrays with Energetic Electrons and Active Sites for Efficient Plasmon-Driven Ammonia Synthesis

Abstract

Direct ammonia (NH₃ ) synthesis from water and atmospheric nitrogen using sunlight provides an energy-sustainable and carbon-neutral alternative to the Haber-Bosch process. However, the development of such a route with high performance is impeded by the lack of effective charge transfer and abundant active sites to initiate the nitrogen reduction reaction (NRR). Here, the authors report efficient plasmon-induced photoelectrochemical (PEC) NH₃ synthesis on the hierarchical free-standing Au/K_x MoO₃ /Mo/K_x MoO₃ /Au nanoarrays. Endowed with energetically hot electrons and catalytically active sites, the plasmonic nanoarrays exhibit an efficient PEC NH₃ synthesis rate of 9.6 µg cm^-2 h^-1 under visible light irradiation, which is among the highest PEC NRR systems. This work demonstrates the rationally designed plasmonic nanoarrays for highly efficient NH₃ synthesis, which paves a new path for PEC catalytic reactions driven by surface plasmons and future monolithic PEC devices for direct artificial photosynthesis.

Keywords: NH 3 synthesis; free-standing nanoarrays; localized surface plasmon resonance; photoelectrochemical catalysis; solar energy conversion.