Recent advances in transition metal-based photocatalytic heterojunctions for algal inhibition and water disinfection: A review

Sustainable energy production and effective water pollution control are critical global priorities. Harmful algal blooms (HABs) and waterborne pathogens pose significant threats to water quality and public health, necessitating efficient and eco-friendly treatment methods. Transition metal-based photocatalytic heterojunctions offer promising solutions by leveraging the unique properties of transition metals to enhance photocatalytic efficiency. This review examines recent advances in these heterojunctions employed for algal inhibition and water disinfection, discussing various heterojunction type (including conventional, p-n, Z-scheme, S-scheme, and Schottky heterojunctions), and their synthesis methods. We elucidate the mechanisms involved, highlighting improved electron transfer, reduced recombination rates, and broadened light absorption. Recent studies on their effectiveness in inhibiting harmful algae and disinfecting water are also reviewed. Current challenges and future research directions to optimize these materials are identified. This is a first comprehensive overview focusing on the contributions of transition metals in photocatalytic heterojunctions for water treatment, aiming to support the development of sustainable technologies.