In laboratories and under open skies, scientists have coaxed a three-layered nanoscale device into doing what leaves have done for billions of years — capturing light and turning it into something useful. Researchers have built a biomimetic nanoreactor that simultaneously produces hydrogen fuel and converts lactic acid into a valuable industrial compound, all without the expensive noble metals that have long constrained such ambitions. The achievement, demonstrated at a scale of 1000 square centimeters under natural sunlight, does not yet promise an industrial revolution, but it quietly advanc