Face-to-Face 2D/2D Heterojunction Between Layered Photocatalysts

Face-to-face 2D/2D heterojunctions have emerged as a transformative strategy in photocatalysis, offering unparalleled charge separation and transport efficiency. The atomically intimate interfaces facilitate favourable charge transfer while minimizing undesirable recombination losses, unlocking new possibilities for solar-to-chemical energy conversion. By precisely engineering layered photocatalysts – such as Bi-based nanomaterials, transition metal dichalcogenides, MXenes and others – these heterojunctions achieve optimal band alignments, significantly enhancing photocatalytic redox reactions for water splitting, carbon dioxide reduction and nitrogen fixation. Cutting-edge advancements through in-situ synthesis approach and ex-situ electrostatic self-assembly have been extensively explored to fabricate a wide range of 2D/2D heterostructures with desired charge transfer mechanisms to enhance the photocatalytic performance. Henceforth, this chapter provides a comprehensive exploration of the fundamental principles, structural classifications, synthetic strategies, and emerging applications of 2D/2D heterojunction photocatalysts. By highlighting the recent breakthroughs and future directions, we underscore the transformative potential of these layered architectures in shaping next generation photocatalysts for renewable energy harvesting and environmental remediation.