Highly Selective Photoreduction of CO₂ with Suppressing H₂ Evolution over Monolayer Layered Double Hydroxide under Irradiation above 600 nm

Abstract

Abstract Although progress has been made to improve photocatalytic CO 2 reduction under visible light ( λ >400 nm), the development of photocatalysts that can work under a longer wavelength ( λ >600 nm) remains a challenge. Now, a heterogeneous photocatalyst system consisting of a ruthenium complex and a monolayer nickel‐alumina layered double hydroxide (NiAl‐LDH), which act as light‐harvesting and catalytic units for selective photoreduction of CO 2 and H 2 O into CH 4 and CO under irradiation with λ >400 nm. By precisely tuning the irradiation wavelength, the selectivity of CH 4 can be improved to 70.3 %, and the H 2 evolution reaction can be completely suppressed under irradiation with λ >600 nm. The photogenerated electrons matching the energy levels of photosensitizer and m‐NiAl‐LDH only localized at the defect state, providing a driving force of 0.313 eV to overcome the Gibbs free energy barrier of CO 2 reduction to CH 4 (0.127 eV), rather than that for H 2 evolution (0.425 eV).