Cu‐Pd Dual Single Atoms Promoting Selective CO ₂ Photoreduction to C ₂ Products in Seawater

The solar‐powered CO 2 conversion via the photocatalysis route offers a sustainable pathway toward carbon neutrality while mitigating energy/environmental pressure. Nevertheless, the selective and efficient conversion of CO 2 via photoreduction to C 2 products remains a formidable challenge. Here, we engineered a dual‐single‐atom photocatalyst by controllably embedding Pd and Cu single atoms into a TiO 2 matrix. The optimized catalyst (Cu 0.5 Pd 0.5 /TiO 2 ) exhibits the outstanding yield (119.2 µmol/g cat ) and selectivity (84.8%) for acetic acid production from CO 2 photoreduction, performed in seawater and in a photothermal‐aided reactor. Various in situ/ex situ characterizations were employed to investigate atomic‐level structure‐performance correlation and reaction mechanism in practical condition. In situ x‐ray photoelectron spectroscopy, in situ atomic force microscopy‐Kelvin probe force microscopy, transient‐state surface photovoltage, and in situ electron paramagnetic resonance (EPR) collectively indicate that loading Pd and Cu single atoms onto TiO 2 apparently accelerates charge kinetics. This modification results in increased photogenerated electrons for CO 2 reduction, facilitating C─C coupling and hydrogenation reactions. Additionally, in situ infrared (IR) spectroscopy and theoretical computations affirm the pivotal function of Pd single atoms for lowering the energy barrier to form the * OCCO intermediate, apparently improving selectivity for acetic acid production. Overall, our work presents an innovative approach to tackle kinetic and thermodynamic challenges for light‐induced CO 2 ‐to‐C 2 conversion.