The JC STEM Lab of Circular Bio-economy (the Lab) at City University of Hong Kong (CityUHK) has recently achieved a breakthrough in the field of sustainable development technologies. A research team led by Professor Lee Duu-Jong, Director of the Lab and Professor in the Department of Mechanical Engineering, has successfully developed a bio-inspired "all-weather building skin" that cools in sunlight and harvests energy from rain, alongside a "turbocharged" solar hydrogen system powered by low-cost copper ions. These innovations provide a transformative pathway for urban energy conservation and clean energy production, reinforcing the Lab's commitment to translating cutting-edge research into tangible social benefits. Under Professor Lee’s leadership, the Lab is dedicated to shifting the traditional linear "take–make–dispose" model into a circular bioeconomy framework. "The core of a circular bio-economy lies in creating 'closed-loop' systems that enable continuous recycling of resources throughout the production and consumption cycle," said Professor Lee. Inspired by the layered leaf structure of the Tillandsia air plant, Zeng Yijun, a PhD student of the Department of Mechanical Engineering (MNE), developed "BRIDGE skin", a paintable, all-weather building coating. This technology enables building envelopes—including roofs and walls — to harness free natural resources to achieve both energy savings and electricity generation under changing weather conditions. In sunny conditions, the coating reflects over 95% of solar energy and emits stored heat as infrared radiation into space. This reduces surface temperatures by up to 9.5°C below ambient levels, significantly reducing air-conditioning electricity demand. During rainfall, the impact of water droplets triggers electrical pulses. This energy is sufficient to power small liquid-crystal displays (LCDs) or wireless sensors directly. Traditionally, integrating electrodes and energy-harvesting layers often compromises a material’s ability to reflect sunlight and radiate heat. Inspired by the stratified structure of Tillandsia air plants, the team overcame this limitation. By adopting a stratified