Recent Breakthroughs in Overcoming the Efficiency Limits of Photocatalysis for Hydrogen Generation

For five decades, photocatalysis has promised clean hydrogen from solar energy, yet a persistent “efficiency ceiling”, linked to fundamental challenges including the trade-off between light absorption and redox potential in single-component materials, has hindered its practical application. This review illuminates three key paradigm shifts overcoming this challenge. First, we examine Z-scheme and S-scheme heterojunctions, which resolve the bandgap dilemma by spatially separating redox sites to achieve both broad light absorption and strong redox power. Second, we discuss replacing the sluggish oxygen evolution reaction (OER) with value-added organic oxidations. This strategy bypasses kinetic bottlenecks and improves economic viability by co-producing valuable chemicals from feedstocks like biomass and plastic waste. Third, we explore manipulating the reaction environment, where synergistic photothermal effects and concentrated sunlight can dramatically enhance kinetics and unlock markedly enhanced solar-to-hydrogen (STH) efficiencies. Collectively, these strategies chart a clear course to overcome historical limitations and realize photocatalysis as an impactful technology for a sustainable energy future.