“MoFe cofactor” inspired iron mesh-based MIL-88A(Fe/Mo) for bionic photocatalytic nitrogen fixation

Abstract

Biomimetic photocatalytic nitrogen fixation is considered as a potential alternative to the Haber-Bosch method, which is an ideal pathway for nitrogen reduction. The development of efficient bionanocatalysts is a serious challenge in the current field of biomimetic nitrogen fixation. Here, we introduced a second metal in the MIL-88A/Fe mesh by metal doping to build a Mo-doped MIL-88A(Fe/Mo)/Fe mesh biomimetic system. The catalyst is a rod-like structure synthesized in situ by hydrothermal method using iron mesh as the substrate, and its rough surface is favorable for the adsorption of N2. The introduction of Mo provides a two-electron transfer pathway for the reaction, and the formation of the "MoFe cofactor" effectively promotes charge separation and inhibits the photoelectron-hole complexation. In addition, we kept the catalyst above the liquid surface and provided the proton source through water vapor, which solved the problem of the low solubility of N2 in water and poor mass transfer efficiency. The results show that the biomimetic photocatalyst has good photoresponsiveness in the whole visible region, and the synergistic effect between the two metals makes the MIL-88A (Fe/Mo0.017)/Fe mesh exhibit better photocatalytic performance, and its nitrogen fixation efficiency reaches about 9.6 times that of the original MIL-88A/Fe mesh. This study provides a new idea for the design of photocatalytic ammonia biomimetic photocatalysts.