Induced Restructuring of a Supramolecular Metal‒Organic Framework Into a Cu─Zn Alloy Catalyst for Reverse Water-Gas...

In Cu-Zn catalysts used for the reverse water-gas shift (RWGS) reaction, Cu and Zn phases remain dispersed, while the Cu-Zn interphase is widely regarded as the catalytically active site. Herein, we engineered a ZnO-decorated Cu-rich Cu-Zn alloy using a mixed Cu/Zn oxalate-based supramolecular metal-organic framework precursor with compositionally homogeneous Cu/Zn mixing. The resulting Cu-Zn catalyst (Cu-Zn|C-oxo|R) maintained >99% CO selectivity and, at 550°C, delivered a Cu-normalized CO space-time yield (STY) of 1580 mmol_CO g_Cu ^-1 h^-1, higher than those of the Cu-only and commercial Cu-Zn-Al benchmarks. Under a high space velocity test, the Cu-Zn|C-oxo|R catalyst remained stable for >50 h at 550°C. Operando Cu K-edge x-ray absorption spectroscopy shows that Cu is reduced to a predominantly metallic local environment that persists under RWGS conditions. Complementary in situ x-ray diffraction and electron microscopy identify Cu-rich Cu-Zn alloy domains in contact with ZnO, while in situ diffuse reflectance infrared Fourier transform spectroscopy is consistent with an associative formate-mediated RWGS pathway at these interfaces. Density functional theory calculations further revealed that these interfacial sites favor the formate reaction pathway, providing a molecular-level rationale for the enhanced catalytic activity.