Although progress has been made to improve photocatalytic CO2 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 CO2 and H2O into CH4 and CO under irradiation with λ>400 nm. By precisely tuning the irradiation wavelength, the selectivity of CH4 can be improved to 70.3 %, and the H2 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 CO2 reduction to CH4 (0.127 eV), rather than that for H2 evolution (0.425 eV).

Single Ru atoms are uniquely located on the top of trivalence Fe atom of NiFe layered double hydroxide.

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Reduction of photocatalytic CO 2 into renewable hydrocarbon solar fuels is considered to be a promising strategy that can simultaneously address global energy needs as well as environmental concerns. To date, making use of a higher wavelength for photocatalytic conversion of CO 2 to CH 4 continues to be highly challenging. In this work, we report a highly selective reduction of CO 2 into CH 4 and CO by introducing Ni species into CoFe-layered double hydroxide (LDH) as the visible light photocatalyst in conjunction with a Ru complex sensitizer. A more interesting finding is that the selectivity of CH 4 was raised to 78.9% as compared to 0% of CoFe-LDH, while the H 2 evolution was suppressed to 1.7% as compared to 30.5% of CoFe-LDH under light irradiation at λ > 500 nm. The involvement of Ni 2+ ions in the CoFe-LDH layers has shown to promote the photoinduced electron−hole pair separation and thereby facilitate the photocatalytic efficiency. This work provides a new strategy for exploring the Ni-based earth-abundant photocatalysts for CO 2 photoreduction.

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