Polarization-induced efficient charge separation in an electromagnetic coupling MOF for enhancing CO₂ photocatalytic...

Rapid recombination of photogenerated carriers severely impairs the performance of photocatalysts, while polarization is an effective driving force for increasing the charge separation and hence improving the photocatalytic activity. In this work, a series of magnetoelectric-coupled layered metal-organic framework (MOF) catalysts with different Co-doped contents (denoted as Ni-MOF and Co_xNi_1-x-MOF) are fabricated with different polarities and employed as novel photocatalysts for CO₂ photocatalytic reduction reaction. Our experiments show that the highest charge separation efficiency occurs in the Co_0.1Ni_0.9-MOF sample which has a maximal polarization. This Co_0.1Ni_0.9-MOF material has a best CO₂ reduction performance of 38.74 μmol g^-1h^-1 which is at a high level in the currently reported layered materials. Meanwhile, it is found that a series of Co_xNi_1-x-MOF samples all display selectivity close to 100% for CO₂ reduction to CO, which is desirable for industrial applications. Theoretical analysis shows that Co doping alters the degree of distortion of the asymmetrical Ni-centered octahedron {NiN₂O₄} in Ni-MOF by replacing Ni due to the magnetoelectric coupling effect and Jahn-Teller effect, which results in adjustable polarity of Co_xNi_1-x-MOF. This work provides new insights on how to improve photogenerated charge separation in MOF by enhancing polarization.