<i>In Situ</i> -Generated CO Drives Dynamic Ni–Zn Restructuring to Govern Kinetic Selectivity in CO ₂ Hydrogenations

The rational design of selective, earth-abundant Ni-based catalysts for the reverse water–gas shift (RWGS) reaction is often hampered by an incomplete understanding of their operando active states. This study reveals that the CO2 hydrogenation selectivity over Ni–Zn catalysts is governed by a support-dependent, reaction-induced dynamic restructuring, rather than by any static, preformed sites. Through a combination of in situ characterization and theoretical calculations, we demonstrate that the active Ni–Zn intermetallic core encapsulated by ZnO forms dynamically only under the RWGS atmosphere on ZrO2 and TiO2 supports, but not on Al2O3 or during mere H2 reduction. Crucially, we identify in situ-generated CO as the essential inducer of this reconstruction, likely via facilitating ZnO reduction. Furthermore, the product selectivity (CO vs CH4) is dictated by the kinetic competition between CO desorption and its deep hydrogenation, a principle quantitatively linked to the evolved electronic structure of the active surface. This work shifts the paradigm toward designing catalysts that evolve into optimal structures in operando and provides a fundamental kinetic framework for selective CO2 conversion.