Flame-Made Surface-Substituted Copper–Ceria as an Excellent Reverse Water–Gas Shift Reaction Catalyst via Three Reaction Pathways
Bingqiao Xie, Yi Zhu, Mahdi Shakeri, Seongmin Jin, George E. P. O'Connell, Sankhadip Saha, Mounir Mensi, Priyank V. Kumar, Jeremy S. Luterbacher, Emma C. Lovell, Rose Amal, Oliver Kröcher
Abstract
High Resolution Image Download MS PowerPoint Slide The limited mechanistic understanding and ambiguous structure–performance relationships have hindered the optimization of Cu-based catalysts for the reverse water–gas shift (rWGS) reaction. Here, we report a flame spray pyrolysis (FSP)-derived Cu–CeO 2 catalyst featuring highly dispersed, surface-substituted Cu + species (Cu y Ce 1– y O 2– x ) anchored on a defect-rich ceria matrix. This catalyst demonstrates excellent stability and outstanding rWGS activity at 600 °C, achieving a CO production rate of 8094 mmol/g cat. /h, surpassing the conventional Cu–CeO 2 catalyst and other reported rWGS catalysts. In situ spectroscopic analyses, supported by DFT calculations, reveal three parallel reaction pathways in which carboxylate- and formate-mediated routes proceed at distinct active sites. A clear structure–activity correlation is established across Cu +, Cu 0, and ceria defect sites in the FSP-derived catalysts. Notably, a previously underexplored carboxylate-mediated pathway, facilitated on the surface-substituted Cu + structure, is identified as the dominant route, featuring a significantly lower apparent activation energy (20–30 kJ/mol) compared to the classical formate pathway.