Copper Phyllosilicate-Derived Cu Catalyst for the Water–Gas Shift Reaction: Insight into the Role of Cu+–Cu0 and Reaction Mechanism

Cu-based catalysts have been extensively researched for hydrogen production via water–gas shift (WGS, CO+H2O↔CO2+H2) reaction. Yet, the catalyst easily suffers from performance degradation due to Cu+/Cu0 transformation and particle aggregation. Herein, copper phyllosilicate with different morphologies, i.e., tubular and lamellar, was fabricated by a modified hydrothermal method for the WGS reaction. Compared with the catalyst derived from lamellar copper phyllosilicate (30Cu/SiO2-L), the one derived from the tubular phyllosilicate (30Cu/SiO2-T) demonstrates better performance due to the high Cu+/(Cu0+Cu+) ratio. In situ characterizations were conducted to unveil the transformation between Cu+ and Cu0, which is highly correlated to the CO and H2O activation. Cu+ is primarily responsible for the activation of CO, while Cu0 mainly facilitates the dissociation of H2O. The results show that 30Cu/SiO2-T follows the redox mechanism, where CO reduces Cu+ to Cu0 and H2O oxidizes Cu0 to Cu+, maintaining the reaction cycle.