Photoreduction of Carbon Dioxide to Formic Acid with Fe-Based MOFs: The Promotional Effects of Heteroatom Doping and Alloy Nanoparticle Confinement

The development of photocatalytic systems with high activity to trigger CO2 reduction into formic acid (FA, HCOOH), which is regarded as a promising hydrogen storage compound, is an attractive option for simultaneously solving energy and environmental problems. The effects of heteroatom doping as well as the confinement of Pd alloy nanoparticles (NPs) on an amine-functionalized Fe-based metal organic framework (Fe-3-MOF) were investigated. The substitution of different metals in the metal cluster nodes significantly changed the CO2 adsorption capacity as well as the CO2 activation properties under visible light irradiation, with Mn2+ doping particularly improving the performance of both. The confinement of PdAu NPs inhibited electron-hole recombination by efficiently trapping excited electrons and then promoting photocatalytic FA production. By optimizing the parameters, a high FA production of 725 mu mol.g(-1) can be achieved after 24 h, which is 3.6 times greater than that obtained with unmodified Fe-3-MOF. The results of the present study have the potential to greatly enrich the applications of MOF-based photocatalysts with the aim of developing economical CO2-mediated hydrogen storage energy cycling.

Automated summary

The study investigated the effects of heteroatom doping and confinement of Pd alloy nanoparticles on an Fe-3-MOF, with Mn2+ doping improving performance significantly and PdAu NPs confining inhibiting electron-hole recombination. Optimization led to a high formic acid production, demonstrating potential for developing economical CO2-mediated hydrogen storage energy cycling.