Conductive Zeolite Supported Indium-Tin Alloy Nanoclusters for Selective and Scalable Formic Acid Electrosynthesis.

Abstract

Upgrading excess CO₂ toward the electrosynthesis of formic acid is of significant research and commercial interest. However, simultaneously achieving high selectivity and industrially relevant current densities of CO₂-to-formate conversion remains a grand challenge for practical implementations. Here, an electrically conductive zeolite support is strategically designed by implanting Sn ions into the skeleton structure of a zeolite Y, which impregnates ultrasmall In_0.2Sn_0.8 alloy nanoclusters into the supercages of the tailored 12-ring framework. The prominent electronic and geometric interactions between In_0.2Sn_0.8 nanoalloy and zeolite support lead to the delocalization of electron density that enhances orbital hybridizations between In active site and *OCHO intermediate. Thus, the energy barrier for the rate-limiting *OCHO formation step is reduced, facilitating the electrocatalytic hydrogenation of CO₂ to formic acid. Accordingly, the developed zeolite electrocatalyst achieves an industrial-level partial current density of 322 mA cm^-2 and remarkable Faradaic efficiency of 98.2% for formate production and stably maintains Faradaic efficiency above 93% at an industrially relevant current density for over 102 h. This work opens up new opportunities of conductive zeolite-based electrocatalysts for industrial-level formic acid electrosynthesis from CO₂ electrolysis and toward practically accessible electrocatalysis and energy conversion.