Recent advances in the development of quantum dots-based photocatalysts for water and energy applications: Critical challenges, outlooks and promises
J.P. Steffy, Prasad Krishna, S. Sudheer Khan
Abstract
Quantum dots (QDs) have emerged as next-generation photocatalysts owing to their quantum confinement effect, tunable bandgap, high surface-to-volume ratio, and superior charge separation efficiency, enabling transformative applications in energy conversion and environmental remediation. This review provides a comprehensive and critical overview of recent advances in QDs synthesis and photocatalytic applications, with a particular focus on water treatment, hydrogen evolution, CO 2 reduction, and nitrogen fixation. We highlight the evolution of synthesis strategies, encompassing advanced hot-injection methods refined via green solvents, microwave, ultrasonication, and solvothermal modifications, alongside non-hot-injection approaches such as aqueous, biosynthetic, microfluidic, and high-gravity techniques, which offer low-cost, eco-friendly, and scalable alternatives. The review establishes clear correlations between synthesis innovations and QD optoelectronic properties, emphasizing their role in pollutant degradation, multi-electron transfer, and reactive species generation. Importantly, it critiques current challenges, including photostability, scalability, toxicity of heavy-metal QDs, low selectivity in CO 2 reduction, and the limited validation of QDs under real wastewater conditions. Finally, future perspectives underscore the need for green, reproducible synthesis protocols, defect and heterojunction engineering, in-situ mechanistic studies, and interdisciplinary integration of computational modelling and materials design. By coupling synthesis evolution with targeted application insights, this review delivers both depth and vision, establishing a roadmap for advancing QDs toward commercial viability in sustainable energy and environmental remediation.