Advances in carbon-dots based nanomaterials for electrocatalytic water splitting: Fundamental, challenges, and future prospects

Although electrocatalytic water splitting, which involves the hydrogen evolution reaction (HER) at the cathode and the oxygen evolution reaction (OER) at the anode, is an effective method for producing green hydrogen, it is constrained by slow kinetics and the exorbitant expense of catalysts derived from noble metals. In this context, carbon dot (CD)-based nanomaterials have shown remarkable performance due to their low cost, tailorable surface functionalization, high electrical conductivity, high stability, and size-dependent catalytic activity. These features provide superior charge transfer, optimized intermediate adsorption, and enhanced catalytic effectiveness, positioning CDs as formidable alternatives for effective electrocatalytic water splitting. Despite considerable research on CD-based nanomaterials for electrocatalytic water splitting, significant gaps persist in existing studies that lack comprehensive insights into advanced techniques such as heteroatom doping, hybridization, and surface engineering. This review paper provides a comprehensive investigation of recent advancements in the fabrication, modification strategies, and performance of carbon dot-based nanomaterials in electrocatalytic water splitting. Herein, we meticulously examined advanced strategies, including heteroatom doping, heterostructure engineering, and interface manipulation, along with cutting-edge characterization techniques, to enhance our mechanistic understanding and elevate the electrocatalytic efficiency of carbon dot-based nanomaterials for water splitting. This review consolidates existing information and highlights outstanding challenges, offering a strategic framework to direct future research in this domain. Furthermore, this review seeks to advance innovation at the convergence of carbon nanotechnology and electrocatalysis, thereby facilitating the emergence of a hydrogen-based energy economy.