NiFe₂O₄ spinel engineering for transcending the dilemma of activity-selectivity in CO₂ hydrogenation to ethanol.

Abstract

CO₂ hydrogenation to ethanol serves as a potential route for carbon neutrality and renewable energy utilization, while its practical application is severely limited by the activity-selectivity trade-off. This challenge primarily arises from the difficulty of C-C coupling and the occurrence of multiple side reactions. Herein, we design a NiFe₂O₄ spinel-modified Fe₂O₃ catalyst via a solid-state co-precipitation method, achieving a high CO₂ conversion rate of 49.3% with an ethanol space-time yield of 883.7  mg·g_cat.^-1· h^-1. Further mechanism investigation reveals that the incorporation of NiFe₂O₄ spinel benefits the formation of active Fe₅C₂ phase. Meanwhile, the interfacial sites between NiFe₂O₄ and Fe₂O₃ endow the catalyst with superior hydrogenation ability, which effectively inhibits excessive carbon chain growth and promotes the orientated synthesis of ethanol. This work proposes an inspiring NiFe₂O₄ spinel engineering method for the efficient production of multi-carbon oxygenates from CO₂ hydrogenation.