Highly Efficient CO₂ Electroreduction in Artificial Seawater Electrolyte Catalyzed by Strong-Acid/Base-Resistant MOF

NaCl, a primary component of seawater, is a cost-effective alternative electrolyte for CO₂ electroreduction; however, suppressing competitive hydrogen evolution reaction (HER) remains a challenge for efficient CO₂RR. Herein, a novel Zn-MOF {[Zn₅(tz)₆(HCOO)₄]·2H₂O}_n (1, Htz = 1,2,3-triazole) was prepared, exhibiting excellent stability in 0.5 M NaCl electrolyte for 16 weeks. 1 could maintain crystalline structure even after exposure to 9 M HCl and 2 M NaOH solutions. 1 achieved high selectivity for the electroreduction of CO₂ to CO with a maximum faradaic efficiency (FE_CO) of 94.4% under -1.5 V in artificial seawater electrolyte and 91.1% FE_CO in treated natural seawater under -0.8 V, maintaining performance over 20 h. The mechanism analysis demonstrated that micropores in 1 could anchor coordinated H₂O in [Na(H₂O)₅]⁺ to form a cationic layer at the particle surface, inhibiting the competitive HER and enhancing catalytic activity. Moreover, 1 could be applied in hectogram-scale production with low cost of US$ 0.01405 g^-1, showing promising industrial potential in CO₂RR. This work addresses a critical challenge of the strongly competitive HER in Na-based electrolytes during electrochemical CO₂RR, offering a feasible strategy for designing stable, efficient, and economical catalysts for sustainable energy applications.