Highly Efficient and Selective Visible-Light Driven Photoreduction of CO 2 to CO by Metal-Organic Frameworks-Derived NiCoO Porous Microrods.

Photocatalytic CO 2 reduction by solar energy into carbonaceous feedstock chemicals is recognized as one of the effective ways to mitigate both the energy crisis and greenhouse effect, which fundamentally relies on the development of advanced photocatalysts. Here, the exploration of porous microrod photocatalysts based on novel NiCoO solid solutions derived from bimetallic metal-organic frameworks (MOFs) is reported. They exhibit overall enhanced photocatalytic performance with both high activity and remarkable selectivity for reducing CO 2 into CO under visible-light irradiation, which are superior to most related photocatalysts reported. Accordingly, the Ni 0.2 -Co 0.8 -O microrod (MR-N 0.2 C 0.8 O) photocatalyst delivers high efficiency for photocatalytic CO 2 reduction into CO at a rate up to ≈277 µmol g -1 h -1 , which is ≈35 times to that of its NiO counterpart. Furthermore, they display a high selectivity of ≈85.12%, which is not only better than that of synthesized Co 3 O 4 (61.25%) but also superior to that of reported Co 3 O 4 -based photocatalysts. It is confirmed that the Co and Ni species are responsible for CO 2 CO conversion activity and selectivity, respectively. In addition, it is verified, by adjusting the Ni contents, that the band structure of NiCoO microrods can be tailored with favorable reduction band potentials, which thus enhance the selectivity toward CO 2 photoreduction.