Heterojunction photocatalysts: where are they headed?

Heterojunction photocatalysts have gained attention for their potential to enhance performance in light-driven, bias-free redox reactions. By integrating two or more semiconducting materials, these photocatalysts exhibit improved light absorption, more efficient charge separation, and enhanced charge transfer. They also enable better alignment of band edge potentials with the redox potentials of reactants, which can promote the selective formation of desired products with higher yields. Recent advancements in characterization techniques and theoretical calculations have provided deeper insights into optimizing charge transfer processes and effectively managing photoexcited charges on the surface. However, key questions remain: how far can heterojunction photocatalysts progress? And what steps are needed to move beyond lab-scale demonstrations? In this perspective, we discuss the status and challenges of heterojunction photocatalysis, aiming to encourage further discussion within the catalysis community to drive this research area toward meaningful progress rather than mere academic hype.