Bimetallic zinc–cobalt ZIF derived hollow dodecahedral ZnCoS nanoparticles with Li⁺-mediated effect for enhanced electrochemical nitrogen fixation

Electrocatalytic N₂ reduction to ammonia synthesis offers a promising alternative to the energy-intensive Haber-Bosch process. Herein, a hollow dodecahedral zinc-cobalt bimetallic sulfide electrocatalyst is demonstrated to effectively boost the electrocatalytic NRR activity with high selectivity by Li⁺-mediated. The ZnCoS catalyst with sufficient active sites achieves a notable NH₃ yield of 20.46 μgh⁻¹mg⁻¹_cat. and a Faradaic efficiency reaching 10.21 % in 0.1 M Li₂SO₄, which is much higher than that of pure ZnS or pure CoS_x. The catalyst shows robust electrochemical and structural stability. Density functional theory (DFT) calculations confirm that N₂ preferentially chemisorption on the cobalt sites of the ZnCoS (111) surface. Zn sites motivate the generation of active hydrogen for N₂ activation. The interaction with Li ⁺ effectively accelerates the kinetics of NRR while concurrently suppressing the HER. The energy barrier of the rate-determining step (∗N₂→∗N₂H) decreased from 1.86 to 1.25 eV, which is beneficial for enhancing the NRR with an alternating reaction pathway. This work provides a feasible strategy for developing high-performance electrochemical N₂ fixation.