Precision nanoengineering of photoelectrochemical devices via atomic layer deposition

Atomic layer deposition (ALD) has become a versatile technique for engineering photoelectrochemical (PEC) devices through atomic-scale control of film composition and thickness, while ensuring excellent conformality. Through its sequential, self-limiting surface reactions, the technique enables controlled and conformal deposition of protective, catalytic, and light-absorbing layers across diverse materials platforms. This review comprehensively examines semiconductor-based ALD strategies that modulate band alignment, defect passivation, and charge transport in key photoelectrode materials such as TiO 2 , Fe 2 O 3 , WO 3 , BiVO 4 , Cu 2 O, and Ta 2 O 5 . Representative studies reporting performance metrics such as photocurrent enhancement, catalytic activity, and reaction kinetics are summarized to highlight the diverse roles ALD plays in PEC systems. These roles are delineated into protective layers, catalytic interlayers, and semiconductor heterojunctions, linking atomic-scale control to macroscopic performance. The review also highlights emerging directions, including interface grading, angstrom-scale dopant engineering, area-selective and spatial ALD, in situ monitoring, and scalable manufacturing. Together, these advances position ALD as a precision fabrication process that bridges fundamental interface design with industrially relevant PEC implementation, advancing the realization of efficient and durable solar-fuel technologies.