Photothermal Steering of the CH₄─CO₂ Coupling Pathway and Coke-Suppression Mechanism by Ni^δ+─O_v─Al Interfacial Sites

High-temperature carbon deposition is a major challenge in dry reforming of methane (DRM), mainly arising from insufficient generation and sluggish migration of reactive oxygen species. Combining interfacial vacancy engineering with photothermal synergistic catalysis is a promising solution, yet their synergistic mechanism remains unclear. Here, a simple alkaline etching strategy was employed to construct stable Ni^δ+-O_v-Al interfacial sites on a NiMgAl-A catalyst. These sites enhanced Ni dispersion and promoted continuous electron transfer from Ni to the support. In situ characterization and theoretical calculations revealed that Ni^δ+-Ov-Al sites serve as both intrinsic active centers for CH₄/CO₂ activation and interfacial electron traps that improve charge separation under illumination. As a result, photogenerated carriers accelerate reactive oxygen species formation, facilitating the direct conversion of CH₄ and CO₂ into CH_xO* intermediates and effectively suppressing coke formation. Photothermal DRM tests at 600°C demonstrated strong synergy between photoelectrons and Ni^δ+-Ov-Al sites. Compared with pristine NiMgAl, NiMgAl-A increased CH₄ and CO₂ conversion rates by 1.55 and 1.61 times, respectively, while reducing the carbon deposition rate from 0.57 to 0.12 g·h^-1. This work provides mechanistic insight into oxygen-vacancy/photoelectron synergy for designing efficient carbon-resistant DRM catalysts.