Theoretical investigation of novel p-block metal-based electrocatalysts for nitrogen reduction reaction

Abstract The electrochemical nitrogen reduction reaction (NRR) is regarded as the most promising alternative to the traditional Haber-Bosch route in current context of developing sustainable and green technologies. However, challenges around low kinetics and low selectivity of NRR are significant barriers for this enticing goal. Different from the transition metal-based NRR catalysts that are prevalent in artificial nitrogen fixation, here, novel p-block non-transition metal catalysts, constructed from an Al-doped phosphorene monolayer, are reported for electrochemical NRR through the density functional theory (DFT) calculations for the first time. We surmised the empty sp3-orbital of doped Al with sp3 hybridization can act as strong Lewis acid sites for N2 adsorption and activation. Among investigated concept-models, Al2@P (-para) exhibits a high activity with an ultra-low limiting potential (UL) of −0.31 V, significantly exceeding the benchmark stepped Ru(0001) surface (UL = −0.98 V), which originates from the strong Lewis acid property of Al sites, good activation on adsorbed N2, and improved redox capacity by 2D phosphorene electron reservoir. Additionally, Al2@P (-para) demonstrates high NRR selectivity and thermal stability under ambient conditions. This research offers a new way of designing effective catalysts and will further boost the study of p-block elements for NRR.