A groundbreaking study published in Nano Letters unveils the successful production of eco-friendly solar hydrogen using a quantum semiconductor nanocluster of cadmium selenide, the smallest inorganic semiconductor material. Led by Professor Jiwoong Yang's team at the Daegu Gyeongbuk Institute of Science & Technology, the research highlights the innovative application of a sub-1-nm ultrasmall quantum semiconductor material as a photocatalyst for hydrogen production. The team's unique approach involved creating a stable superstructure for the nanocluster by arranging it three-dimensionally and bonding it with cross-linked ligands, overcoming previous challenges of structural instability and poor electrical properties. The addition of cobalt ions within the cluster further enhanced its electrical properties, leading to effective photocatalytic hydrogen evolution. Professor Yang expressed the significance of this achievement, emphasizing the material's potential for diverse applications beyond energy and environment, including quantum science. This milestone discovery not only showcases the capabilities of quantum semiconductor nanoclusters but also paves the way for sustainable energy solutions. The research, conducted in collaboration with prominent chemistry departments at Hanyang University and Korea University, sets a new standard in the field of nanotechnology and semiconductor research. The implications of this study extend to various industries, promising a future where eco-friendly hydrogen production is a key component of clean energy initiatives.