MOFs on semiconductors

Our research projects

The surface modification of semiconductors can improve photoelectrochemical performance by promoting efficient interfacial charge transfer and the chemical immobilization of MOF thin films, as the surface coating can bring many added benefits. This hybrid photocathode takes advantage of semiconductors by harvesting solar energy to absorb photons and drive the redox reactions at a lower energetic cost, whereas MOFs provide well-defined tunable active sites and long-term stability.

In our recent work, we successfully grew a UiO-type Zr(NDI) MOF and highlighted the role of MOFs in promoting charge separation and enhancing photovoltage (the figure above). We also showed that captured minority charge carriers could translocate through the MOF by hopping and finally can be extracted by an electron acceptor in solution.

Figure. Balance of steady-state photon (I0), interfacial electron transfer (jtr), recombination (jrec), and diffusion-controlled charge (Fq) fluxes with a surface grown MOF thin film. EVB and ECB are the energetic positions of the valence and conduction band, respectively, EF,p and EF,n are the quasi-Fermi levels of the holes and electrons, respectively, Vph is the semiconductor photovoltage, and Efilm is the electrochemical potential of the MOF film. The molecular structure of the linker is pictured on the right. Reprinted with permission from Nat. Commun. 2020, 11, 5819.

Selected references

• Beiler, A. M.; McCarthy, B. D.; Johnson, B. A.; Ott, S. Enhancing Photovoltages at p-Type Semiconductors through a Redox-Active Metal-Organic Framework Surface Coating. Nat. Commun. 2020, 11, 5819. https://doi.org/10.1038/s41467-020-19483-5