Induced Restructuring of a Supramolecular Metal‒Organic Framework Into a Cu─Zn Alloy Catalyst for Reverse Water–Gas Shift
Vijay K. Velisoju, Jon Pascual‐Colino, Pia Dally, Seba Alareeqi, Quaid Johar Samun Virpurwala, Abdallah Nassereddine, Hend Mohamed, David Trueba, Xueqin Bai, Sandra Mena‐Gutiérrez, Bambar Davaasuren, Mohamed Ben Hassine, Natalia Morlanes, Enrique V. Ramos‐Fernández, Antonio Aguilar‐Tapia, Oscar Castillo, Pedro CastañoABSTRACT
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.