Photoelectrochemical reduction of N2 to NH3 under ambient conditions through hierarchical MoSe2@g-C3N4 heterojunctions

Abstract

Ammonia is the main precursor for the production of fertilizers, a hydrogen energy carrier and an emerging clean fuel that plays a crucial role in sustaining life on the globe. Herein, hybrid MoSe₂@g-C₃N₄ micro/nanostructures are described that can serve as photoelectrochemical (PEC) catalysts to fix N₂ into NH₃ in a basic electrolyte at a low potential (−0.3 V vs. RHE) under ambient conditions. In situ functionalization of the hierarchical micro/nanoflowers of MoSe₂ with exfoliated g-C₃N₄ nanosheets dramatically boosts the faradaic efficiency and yield rate up to 28.91% and 7.72 μmol h⁻¹ cm⁻² respectively. The high PEC activity can be attributed to the hierarchical architecture, light-harvesting capability, tunable active sites and formation of heterojunctions, as confirmed by various characterization and density functional theory (DFT) calculations. Therefore, this work not only develops an effective procedure to obtain hierarchical heterojunction catalysts towards a high-efficiency NRR but also provides a deep understanding of artificial N₂ fixation at the MoSe₂@g-C₃N₄ interface.