Boosting electrocatalytic nitrogen fixation on Ni-P codoped MoS2 nanosheets

Abstract

Electrocatalytic nitrogen fixation in an aqueous solution is considered a promising approach to ammonia synthesis. Still, this process has low Faraday efficiency and ammonia yield, so it is necessary to develop an efficient, clean, and safe catalyst to promote nitrogen reduction process. Doping can be easily carried out during the crystal growth owing to the weak interaction between the sandwiched layers (due to van der Waals forces) of MoS2. Here, a Ni-P codoped MoS2 nanosheets is designed as a highly efficient catalyst for electrochemical nitrogen fixation with superior selectivity. Especially, the doping of Ni achieved the transformation of MoS2 from 2 H phase to 1 T phase, improving the conductivity of the material. In addition, the doping of P creates more sulfur vacancies in the catalyst, thereby producing more H*, which promotes the adsorption and activation of nitrogen. The as-synthesized Ni-P codoped MoS2 nanosheets show excellent catalytic performance with a high yield of electrocatalytic ammonia synthesis (84.29 μgNH3 h−1 mgcat−1) and Faraday efficiency (2.39 %) at −0.5 V versus reversible hydrogen electrode in acidic electrolytes (0.005 M H2SO4), which outperformed most electrocatalytic ammonia synthesis catalysts. Furthermore, the Ni-P codoped MoS2 catalyst also shows outstanding electrochemical stability and durability. This work may offer a hopeful lead for designing effective non-noble-metal NRR electrocatalysts.