Controllable construction of cobalt nanoparticles in nitrogen-doped carbon nanotubes for photothermal CO₂ methanation

The development of non-noble metal catalysts for efficient CO₂ methanation reaction under mild conditions remains a significant challenge. Herein, a non-noble metal catalyst, cobalt nanoparticles (Co NPs) encapsulated within the hollow channels of nitrogen-doped carbon nanotubes (Co@CN-700), was prepared by a pyrolysis-reduction strategy for photothermal CO₂ methanation. Remarkably, the Co@CN-700 catalyst achieved a prominent CH₄ production rate of 199.4 mmol g_cat⁻¹ h⁻¹ with near-unity selectivity (99.4%) and high CO₂ conversion (85.8%) at 250 °C, which is outstanding compared to the catalysts reported. The electromagnetic simulation and density functional theory calculations demonstrated that the plasmonic resonance effect of Co NPs enhances the local electric field and thereby alters the intermediate states and rate-limiting step to facilitate CO₂ methanation. This work offers a straightforward and effective approach for designing non-noble metal catalysts with high activity, selectivity, and stability.