Photothermal conversion of CO₂ with high activity and stability over Ni-based composite nanochains

Solar-driven CO₂ conversion to valuable products is a promising way to realize a carbon-neutral economy. Great progress has been made on photothermal catalysts with high selectivity and activity, but improved materials via a more efficient and cost-effective synthetic strategy are needed. Herein, we present a one-pot synthetic strategy of nickel/metal oxide nanostructured chains for the photothermal conversion of CO₂ into methane. Nickel ions were in-situ reduced in a growth solution in the presence of alumina nanocrystals, where the formation and assembly of magnetic nickel nanoparticles decorated with Al₂O₃ nanocrystals simultaneously proceeded. The obtained composite nanochains exhibited a stable production rate of CH₄ as high as 128 mmol·gcat⁻¹·h⁻¹ with ∼ 99% selectivity in continuous cycling test. The structure analysis of the Ni/Al₂O₃ composite indicates that a small amount of Al₂O₃ nanocrystals introduced in the nanocomposites not only ensures sufficient active site exposure to reactive molecules but also prevents the nickel nanoparticles from drastically sintering at high temperatures. The flexibility of this rapid synthesis strategy is also verified by using titania for the synthesis of Ni/TiO₂ nanocatalysts, and stable catalytic performance has been achieved, suggesting its potential for practical solar-driven CO₂ hydrogenation to valuable fuels.