A clean energy future: Hidden “in-between” materials to build solar fuels and batteries

University of Warwick scientists have uncovered a “hidden” version of a clean-energy material (β-BiVO₄) and new battery-friendly structures by studying the intermediate stages of chemical heating

These “in-between” materials, previously overlooked by science, offer new ways to tune the efficiency of solar hydrogen production and increase the storage capacity of future batteries.

Published in Nature Communications, the study reveals that the transition from a starting chemical (A) to a final product (B) contains several intermediate stages that possess unique, useful properties for solar fuels and batteries.

β-BiVO₄

One of the most significant finds is a previously unknown form of bismuth vanadate, dubbed BiVO₄. Bismuth vanadate is a superstar in the clean energy world because its “band gap” allows it to absorb sunlight efficiently enough to split water and create hydrogen fuel.

• Atomic structure:

  • The new β-variant has a different atomic arrangement than the standard form.

• Tuning performance:

  • It possesses a significantly larger band gap, which changes how it interacts with light. This discovery provides scientists with a new “dial” to tune the performance of solar cells and electronic devices.

Beyond solar fuels: A boost for batteries

The study’s implications extend into the world of energy storage. One of the other “in-between” materials identified during the heating process demonstrated a remarkable ability to store large amounts of lithium. This suggests that these intermediate phases, which were previously ignored or unseen, could be key components for next-generation battery technologies.

Seeing the invisible

To capture these fleeting “stepping stone” materials, the team combined several advanced imaging and analysis techniques:

• Solid-state NMR spectroscopy:

  • Used to look at the local environment of atoms.

• X-ray diffraction and pair distribution function analysis:

  • Used to map out the physical structure of the materials as they changed.

By carefully controlling the chemistry of the starting molecules (precursors) and the temperature at which they are heated, the team proved they can “freeze” these kinetic stages that are otherwise impossible to create using standard manufacturing methods.