The commercialization of solar green hydrogen production technology is approaching reality, thanks to a breakthrough in protective materials that significantly enhance the durability of crucial photoelectrodes. Professor Jungki Ryu from UNIST, in collaboration with Professor David Tilley from UZH, has developed a protective layer that improves the longevity of metal oxide-based photoelectrodes used in solar hydrogen production. The protective layer, incorporating polyethyleneimine polymer (PEI) into titanium dioxide (TiO2), selectively allows holes to facilitate water oxidation reactions, ultimately enhancing photoanodes' performance and preventing corrosion. This advancement addresses the critical issue of photoelectrode corrosion during water oxidation, a barrier to technology commercialization. The protective layer has shown remarkable stability, enabling stable water decomposition reactions for over 400 hours at a high current density, a significant improvement compared to unprotected photoelectrodes. This development marks a milestone in low-cost, high-stability solar water decomposition technology, with potential applications in various photoelectrochemical cells utilizing solar energy.