Catalyst Synthesis with Solution Plasma Enhances CO Selectivity in CO₂ Hydrogenation Catalyzed by Highly Dispersed Copper in Mixed Zinc–Zirconium Oxides

We report a solution plasma process for synthesizing highly dispersed copper catalysts on ZnZrO_x 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 Cu^δ+ species (0 < δ < 2). Experimental characterization combined with density functional theory calculations shows that these sites modulate hydrogen activation to produce electrophilic H^δ+ 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 g_CO kg_cat^–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.