Optimizing Interfacial Sites of Ni/ZrO₂ via Morphology-Induced Crystal Phase Modulation to Enhance Photothermal CO₂ Conversion

Photothermal CO₂ conversion into value-added syngas via dry reforming is pivotal for greenhouse gas utilization, yet its efficiency is constrained by catalyst deactivation. Here, we demonstrate that morphology-induced crystal phase modulation of ZrO₂ supports enables effective optimization of interfacial sites in Ni/ZrO₂ catalysts. By engineering cubic (Ni/ZrO₂-C) and stellated (Ni/ZrO₂-S) architectures, a metastable mixed-phase structure (54.8% monoclinic/37.3% tetragonal) is stabilized to achieve precise phase regulation. Systematic characterization reveals that this phase transformation strengthens metal–support interactions, improves Ni dispersion, and generates abundant oxygen vacancies. As a result, Ni/ZrO₂-C achieves 95% ethanol conversion with lower by-product formation and exhibits exceptional stability, with a 50% lower deactivation rate (0.13% h⁻¹) than Ni/ZrO₂-S (0.26% h⁻¹). The enhanced performance is attributed to improved surface basicity and more efficient coke gasification facilitated by interfacial oxygen vacancies. ​Theoretical calculations further confirm kinetically favorable pathways with reduced activation barriers, particularly for carbon oxidation, accounting for the observed 3.2-fold higher activity of Ni/ZrO₂-C. This work establishes morphology-directed crystal phase engineering as a general strategy for designing efficient photothermal catalysts.