Sustainable energy: Controlling light absorption by adding protons to iron compounds' chemical structure

https://phys.org/news/2024-09-sustainable-energy-unveil-ways-absorption.html

"2nd coordination sphere, region of molecule not directly bound to iron atom but nevertheless influences its behavior... iron complexes used as eco-friendly, cost-effective, readily available alternative to rare-earths, are cromophores: converting light to energy... also, properties adapted by protons' addition/ removal... photocatalysis, photovoltaics"