A pH‐Switchable System for On‐Demand Solar Hydrogen Production

Artificial Solar-to-Fuel conversion is a pivotal pathway toward a sustainable energy future. Molecular hydrogen H₂, with its clean energy potential, emerges as a promising candidate to replace fossil fuels. Nevertheless, the intermittent nature of solar irradiation presents a formidable obstacle. Inspired by natural photosynthesis, we employed a well-known three-component system to decouple light absorption and hydrogen evolution. Our system utilizes [Ru(bpy)3]2+, triethanolamine, and methyl viologen to store solar energy as reduced viologen (MV•+). By controlling pH, we can efficiently release this stored energy to produce hydrogen on demand. Our system demonstrates superior efficiency compared to platinum-based catalysts, along with remarkable reversibility, cyclability and stability. This work significantly advances solar-to-hydrogen conversion, providing a promising solution for the intermittent nature of solar energy and paving the way to a sustainable energy future.