Boosted electrochemical ammonia synthesis by high-percentage metallic transition metal dichalcogenide quantum dots

Abstract

The electrochemical method can directly convert N₂ into the high-value-added NH₃ under ambient conditions and is considered to be a green and sustainable alternative to the traditional Haber–Bosch process. However, the electrochemical nitrogen reduction reaction (NRR) suffers from a low ammonia yield rate over the reported electrocatalysts. Herein, we have developed a general strategy to boost the NRR performance, enabled by the metallic 1T phase dominated transition metal dichalcogenide quantum dots (TMD QDs). Impressively, the obtained MoSe₂ QDs achieved a superior ammonia yield rate of 340 μg mg⁻¹ cat. h⁻¹ with excellent ammonia generation sustainability. Experimental and theoretical studies revealed that the excellent catalytic activity of MoSe₂ QDs mainly originates from the ultra-small quantized size (high surface area and high-density active edge/defect sites) and high-percentage metallic 1T phase (the N₂ adsorption on the 1T phase is spontaneous, and the energy barrier of the potential determining step on the 1T phase is very low). Most importantly, our concept is universal for TMD materials (i.e., MoS₂, WSe₂, WS₂ and NbSe₂) that also exhibit a much-enhanced ammonia yield rate as compared to other electrocatalysts.