Engineering Active Ni Sites in Ternary Layered Double Hydroxide Nanosheets for a Highly Selective Photoreduction of CO₂ to CH₄ under Irradiation above 500 nm

Reduction of photocatalytic CO₂ 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 CO₂ to CH₄ continues to be highly challenging. In this work, we report a highly selective reduction of CO₂ into CH₄ 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 CH₄ was raised to 78.9% as compared to 0% of CoFe-LDH, while the H₂ evolution was suppressed to 1.7% as compared to 30.5% of CoFe-LDH under light irradiation at λ > 500 nm. The involvement of Ni²⁺ 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 CO₂ photoreduction.