Atomic-scale CuOx–Fe3O4₋x/TiO2 heterostructures with defect synergy for highly selective and efficient reverse water–gas shift reaction, Chemical Engineering Journal 530, 173387(2026)
Po-Wen Cheng, Fa-Chih Pai, Chien-Yi Liu, Chih-Wei Hu*, Ching-Yi Chou, Guo-Wei Lee, Chia-Shing Wu, Chun-Hong Kuo, Kuang-Kuo Wang, Po-Chun Chen, Tsan-Yao Chen*
2026/05/07
The reverse water–gas shift (RWGS) reaction, which converts CO2 and H2 into CO, is a pivotal step in carbon-neutral energy cycles and chemical feedstock production. While Cu-based catalysts exhibit near-ideal CO selectivity, their activity is limited; conversely, non–Cu-based catalysts, particularly Ni and Co, often suffer from excessive hydrogenation to CH4, leading to a fundamental activity–selectivity trade-off. Here, we report a TiO2-supported Fe3O4₋x catalyst uniformly decorated with atomic-scale CuOx clusters via a combined chemical adsorption–reduction and spontaneous oxidation strategy. Notably, introducing only 0.75 wt% Cu increases the CO and CH₄ production yield of Fe/TiO2 by 653% and 57-fold, respectively—demonstrating exceptional promotional efficiency with minimal Cu loading. The design integrates (i) interfacial electronic modulation through multiple Ti–O–Fe–Cu heterointerfaces to precisely tune lattice oxygen bond energies and stabilize *COOH intermediates; (ii) defect synergy among TiO2 oxygen vacancies, CuOx defect sites, and Fe oxide defect sites to cooperatively promote CO2 activation, Oads removal, and H2 dissociation; and (iii) reaction-pathway optimization to enhance CO yield, suppress CH4 formation, and lower the apparent activation energy, enabling high CO selectivity and productivity below 300 °C. Comprehensive HAADF-STEM, XRD, XAS, and XPS analyses reveal dynamic interfacial electron redistribution and vacancy regeneration under reaction conditions, establishing a direct structure–function relationship. This work provides a mechanistically informed strategy for the rational design of next-generation RWGS catalysts that simultaneously maximize activity, selectivity, and economic viability.