The Korea Institute of Machinery and Materials (KIMM) has made significant advancements in green hydrogen production by developing a technology that efficiently generates hydrogen under natural sunlight. Dr. Jihye Lee and her research team at KIMM have innovatively enhanced the productivity of BiVO4 photoelectrodes, a key material for solar water-splitting systems, to maximize hydrogen production. By simplifying the previous complex multi-step processes, the new technology reduces fabrication time and is projected to accelerate the commercialization of solar-powered hydrogen production. The team's breakthrough includes developing a high-concentration BiVO4 precursor solution that enables a one-step spin coating to produce uniform and high-performance thin films, improving productivity by approximately 5.9 times compared to conventional methods. Additionally, they successfully created an ultra-large photoelectrode system with a 576 cm² area, capable of generating stable and high photocurrents under natural sunlight. By connecting this system with Si solar cells, hydrogen was produced solely using natural sunlight, marking a significant advancement in eco-friendly hydrogen production. Dr. Jihye Lee highlighted the importance of this research in enhancing the efficiency and productivity of large-area photoelectrodes, which are crucial for sustainable energy transition and the commercialization of green hydrogen production. The research team's achievements have led to the filing of domestic and PCT patents, showcasing the potential for widespread adoption of this technology. These developments open doors to mass production of green hydrogen, contributing to a more sustainable and environmentally friendly energy landscape.