Stored sunlight drives hydrogen generation in the dark, no power needed

Researchers have developed a novel liquid-based system that stores solar energy chemically and later generates hydrogen gas in complete darkness without requiring external electricity, wires, batteries, or power grids. The system mimics photosynthesis by first capturing sunlight and converting it into "stored electrons" within a solution composed of two inexpensive, commercially available materials: graphitic carbon nitride (a visible-light-absorbing photocatalyst) and ammonium metatungstate (a tungsten-oxygen cluster that acts like a rechargeable electron storage unit). Methanol is added to the water-based solution to prevent rapid electron-hole recombination, enabling efficient electron storage. Under blue light, electrons generated by carbon nitride transfer to tungsten clusters, reducing tungsten atoms and visibly changing the solution’s color, signaling successful solar energy storage. When illumination stops, the stored electrons remain stable until a platinum-on-carbon catalyst is introduced in the dark, triggering hydrogen production by combining electrons with protons from water. This decouples sunlight capture, energy storage, and hydrogen