Catalyst Synthesis with Solution Plasma Enhances CO Selectivity in CO ₂ Hydrogenation Catalyzed by Highly Dispersed Copper in Mixed Zinc–Zirconium Oxides

We report a solution plasma process for synthesizing highly dispersed copper catalysts on ZnZrOx supports, enabling selective CO production via the reverse water–gas shift pathway. The synthesis simultaneously generates surface oxygen vacancies on the support and reduces Cu precursors, stabilizing low-valent surface Cuδ+ species (0 < δ < 2). Experimental characterization combined with density functional theory calculations shows that these sites modulate hydrogen activation to produce electrophilic Hδ+ species that preferentially stabilize *COOH intermediates while suppressing *HCOO formation, thereby directing the reaction pathway toward CO formation. As a result, a catalyst containing 2.27 wt % Cu achieves a high CO space-time yield of 714 gCO kgcat–1 h–1 at a relatively low temperature, 300 °C. These results indicate that solution plasma synthesis is a viable strategy for tailoring metal-oxide interactions and reaction selectivity in heterogeneous catalysis.