Computational and Experimental Identification of an Earth-Abundant Light Absorber for Solar Water Splitting

Yan, Q. et al. Mn2V2O7: An Earth Abundant Light Absorber for Solar Water Splitting. Advanced Energy Materials, DOI: 10.1002/aenm.201401840 (2015).


Scientific Achievement

Computation, synthesis, and spectroscopy are used to first identify and then study the earth-abundant Mn2V2O7 as a highly promising light absorber for photocatalytic water splitting.

Significance & impact

The detailed understanding of β-Mn2V2O7 photoabsorber reveals that it is a unique metal-oxide semiconductor with desirable band gap and near-perfect band alignment to the standard potentials for water splitting.  This discovery provides a path toward targeted design of additional metal-oxide light absorbers with excellent optoelectronic properties for solar fuels applications.

 

 

 

  Reprinted with permission from Yan, Q. et al. Mn2V2O7: An Earth Abundant Light Absorber for Solar Water Splitting. Advanced Energy Materials, DOI: 10.1002/aenm.201401840(2015).  Copyright (2015) WILEY.

 

Reprinted with permission from Yan, Q. et al. Mn2V2O7: An Earth Abundant Light Absorber for Solar Water Splitting. Advanced Energy Materials, DOI: 10.1002/aenm.201401840(2015).  Copyright (2015) WILEY.

Top left:  Structure of β-Mn2V2O7 light absorber with MnO6octahedra and V2O7 divanadate units; top right:  band structure with electronic bands in the spin-up (black) and spin-down (green) channels; to the right are the site and l-projected electronic densities of states.  Bottom Left:  Final 20 s with 1 Hz chopped illumination, showing stable photocurrent in excess of 0.1 mA cm-2; bottom right:  CBM and VBM in aqueous solution relative to the two water redox potentials.

Research Details

  • A density functional theory (DFT) was used to understand the relevant structural, electronic, and magnetic properties of β-Mn2V2O7
  • Photoabsorber is synthesized and fully characterized, yielding excellent agreement between theory and experimental measurements.
  • In addition, a Mn0.5V0.5Ox sample from a combinatorial composition library was prepared on a conducting substrate, yielding a film characterized by a scanning-drop photoelectrochemical cell.  Photoelectrochemical characterization revealed excellent stability and opportunities for improving the photoelectrocatalytic activity to enable efficient photo-driven water splitting.

 

Contact: qiminyan@lbl.govjbneaton@lbl.govgregoire@caltech.edu