Atomic layer deposition in preparing 2D-NS-photocatalysts for hydrogen generation-a comprehensive review

Abstract

Hydrogen production through photocatalysis, electrocatalysis, and hydrolysis is a promising route to clean energy. However, persistent challenges—including low charge separation efficiency (<10% solar-to-hydrogen (STH)), limited catalyst stability (>1,000 h required), and reliance on noble metals—continue to hinder scalability. Two dimensional nanosheets (2D NS) have emerged as attractive platforms due to their tunable electronic structures and high surface activity, but conventional synthesis methods often fail to deliver uniform coatings, controlled defects, or stable heterojunctions. This limits systematic tuning of catalytic interfaces and prevents achieving both high efficiency and long-term durability in practical hydrogen production systems. This study highlights atomic layer deposition (ALD) as a precise strategy for engineering 2D NS photocatalysts. Representative systems such as COF/SnNb₂O₆ and NiO/CdS heterojunctions achieve 15.2% STH—2.3× higher than pristine SnNb₂O₆—via Z scheme charge transfer with I₃⁻/I⁻ mediators, reducing recombination by 78%. In electrocatalysis, ALD derived boron nanosheets deliver hydrogen evolution reaction (HER) overpotentials of 89 mV at 10 mA/cm², outperforming Pt/C (110 mV), while enabling NaBH₄ hydrolysis rates 4.5× faster than bulk catalysts. ALD strategies ensure scalable synthesis from abundant precursors, >95% durability over 2,000 cycles, and cost reductions of up to 60% compared with noble metal alternatives. By bridging gaps in efficiency, stability, and practicality, ALD engineered 2D nanosheets advance sustainable hydrogen production and accelerate pathways toward commercialization.