A Highly Efficient Mononuclear Iridium Complex Photocatalyst for CO₂ Reduction under Visible Light

Mononuclear iridium(III) terpyridine (tpy) 2-phenylpyridine (ppy) complexes [Ir(tpy)(R-ppy)Cl] (R=H, Me, CF3) can act as efficient and selective CO2 reduction photocatalysts. The reaction is driven using visible light in a homogeneous solution, and even in a H2O mixed solution. The most efficient photocatalyst is [Ir(tpy)(Me-ppy)Cl], for which the turnover in CO was over 50 and the quantum yield was 0.21 at 480 nm.