Dual-optimization strategy engineered Ti-based metal-organic framework with Fe active sites for highly-selective CO2 photoreduction to formic acid

Increasing CO2 conversion efficiency over metal-organic framework (MOF) based photocatalysts is of great significance to promote the carbon capture and utilization. In this work, a dual-benefit design strategy is deployed in the synthesis of a new two-dimensional Fe/Ti-BPDC MOF photocatalyst with atomically dispersed Fe sites. This catalyst demonstrated an excellent catalytic performance in the visible-light-driven CO2 conversion to HCOOH, achieving a high yield of 703.9 μmol g-1 h-1 at a selectivity greater than 99.7%. This is attributed to the ‘dual-optimization’ achieved by this catalyst to sustain the supply of photogenerated electrons and to effectively activate CO2. Specifically, the Fe/Ti-BPDC catalyst provides a high proportion of effective photogenerated electrons for the CO2 photocatalysis process via a unique electron transfer mechanism. Meanwhile, the strong O/Fe affinity between CO2 and atomically dispersed Fe active sites not only enables a fast CO2 activation, but also dictates the intermediate reaction pathways towards high HCOOH selectivity.