Highly light absorptive photocatalysts are of great significance to boost the photothermal conversion efficiency. Light trapping effect of nanoarray structured photothermal catalysts can enhance the light absorption and improve the photothermal conversion efficiency. However, the practical applications of array-based catalysts are hindered by very low loadings of active metal catalysts per unit illumination area. Herein, we develop a SiO₂-protected MOFs pyrolysis method for the preparation of powder-form cobalt plasmonic superstructures that enable a 90% absorption efficiency of sunlight and tunable metal loading per unit area. Its high light absorption capacity was confirmed by time-domain finite-difference simulation calculations due to the plasmonic hybridization effect of nanoparticles. Compared with nanoarray-structured plasmonic superstructures, the powder-form catalyst exhibit enhanced catalytic activity and stability, resulting in the increase of CO₂ conversion efficiency from 0.9% to 26.2%. This study lays the foundation for the practical application of non-precious metal photothermal catalysts.