Developments of photocatalytic overall water splitting to produce H2

Over the past half-century, significant efforts have been dedicated to the photocatalytic H 2 production from H 2 O under UV–visible light irradiation. These endeavors have yielded remarkable results, with efficiency levels now approaching near 100 ​% apparent quantum yields, notably utilizing inorganic semiconducting materials such as modified Al-doped SrTiO 3 photocatalysts. Meanwhile, advancements in organic polymer semiconducting materials, exemplified by g-C 3 N 4 , have led to substantial improvements in the efficiency of photocatalytic overall water splitting for H 2 evolution reaction. These improvements, achieved through chemical engineering methods and molecular-level modifications, have resulted in an apparent quantum yield of 69 ​% at 405 ​nm, accompanied by significant red-shifting of optical absorption to 1400 ​nm. These developments are presented in chronological order over the past half-century, underscoring the ongoing quest for innovative breakthroughs to enable large-scale practical applications of solar hydrogen production. Key considerations in this pursuit include efficiency, stability, cost-effectiveness, and the independent evolution of H 2 and O 2 .