An alternate way to generate green hydrogen is simply by learning from Nature. Yes, the oxygen we breathe is from the photolysis of water occurring in plants. A similar concept was developed five decades earlier using an artificial leaf - nothing but a semiconductor (also referred to as a photocatalyst). It harvests sunlight and generates electrons for reducing protons to form hydrogen. After five decades of its inception, this approach is gaining significant attention in scalable solar hydrogen production. Photocatalyst modules of 100 m2 producing hydrogen under ambient sunlight have recently been demonstrated.

Among tons of materials investigated for water splitting reaction, ABO3-type photocatalysts (such as SrTiO3) outperform in solar-to-hydrogen (STH) energy conversion efficiency (for overall water splitting reaction) and stability exceeding 250 days under ambient sunlight conditions. However, the big issue with these materials is their limited optical absorption ability - less than 4% of incoming sunlight due to their wide band gap. To further enhance the hydrogen production efficiency using ABO3-type perovskite-based photocatalysts, it is crucial to extend the optical response of these materials, typically done by doping. This approach has been utilized by many groups.

Our recent work, which is a cooperation with Manipal Institute of Technology Manipal Academy of Higher Education, revealed an interesting observation – doping does not help. We must be careful about the valence state of the dopant introduced into the perovskite host. Such insight is often ignored, and we explained such intriguing phenomena in detail in this work.

Link: https://pubs.acs.org/doi/10.1021/acsami.3c16710, opens an external URL in a new window