Photoelectrochemical (PEC) artificial leaves hold the potential to lower the costs of sustainable solar fuel production by integrating light harvesting and catalysis within one compact device. However, current deposition techniques limit their scalability¹, whereas fragile and heavy bulk materials can affect their transport and deployment. Here we demonstrate the fabrication of lightweight artificial leaves by employing thin, flexible substrates and carbonaceous protection layers. Lead halide perovskite photocathodes deposited onto indium tin oxide-coated polyethylene terephthalate achieved an activity of 4,266 µmol H₂ g⁻¹ h⁻¹ using a platinum catalyst, whereas photocathodes with a molecular Co catalyst for CO₂ reduction attained a high CO:H₂ selectivity of 7.2 under lower (0.1 sun) irradiation. The corresponding lightweight perovskite-BiVO₄ PEC devices showed unassisted solar-to-fuel efficiencies of 0.58% (H₂) and 0.053% (CO), respectively. Their potential for scalability is demonstrated by 100 cm² stand-alone artificial leaves, which sustained a comparable performance and stability (of approximately 24 h) to their 1.7 cm² counterparts. Bubbles formed under operation further enabled 30–100 mg cm⁻² devices to float, while lightweight reactors facilitated gas collection during outdoor testing on a river. This leaf-like PEC device bridges the gulf in weight between traditional solar fuel approaches, showcasing activities per gram comparable to those of photocatalytic suspensions and plant leaves. The presented lightweight, floating systems may enable open-water applications, thus avoiding competition with land use.

光电化学 (PEC) 人造叶子通过将光收集和催化集成在一个紧凑的设备中，具有降低可持续太阳能燃料生产成本的潜力。然而，目前的沉积技术限制了它们的可扩展性¹，而易碎和笨重的散装材料会影响它们的运输和部署。在这里，我们展示了通过采用薄而灵活的基板和碳质保护层来制造轻质人造叶子。使用铂催化剂，沉积在氧化铟锡涂层的聚对苯二甲酸乙二醇酯上的卤化铅钙钛矿光电阴极的活性为 4,266 µmol H ₂  g ^-1  h ^{-1 ，而具有 CO} ₂分子 Co 催化剂的光电阴极在较低（0.1 太阳）照射下，还原获得了 7.2 的高 CO:H ₂选择性。相应的轻质钙钛矿-BiVO ₄ PEC 器件的无辅助太阳能燃料效率分别为 0.58% (H ₂ ) 和 0.053% (CO)。^{100 cm 2}的独立人工叶片证明了它们的可扩展性潜力，该叶片的性能和稳定性（大约 24 小时）与 1.7 cm ²的同类叶片相当。在操作下形成的气泡进一步使 30–100 mg cm ^-2漂浮装置，而轻型反应堆有助于在河流的户外测试期间收集气体。这种叶状 PEC 装置弥合了传统太阳能燃料方法之间的重量鸿沟，其每克的活性可与光催化悬浮液和植物叶子的活性相媲美。所提出的轻型浮动系统可以实现开放水域应用，从而避免与土地使用的竞争。