Emerging coordination polymer photocatalysts for water splitting: From mechanistic insights and design strategies to application roadmap

Abstract

Growing concerns regarding environmental and energy challenges have substantially contributed in the development of efficient and sustainable PWS (photocatalytic water splitting) techniques has been greatly aided by. Beyond enormous photocatalytic materials, CPs (coordination polymers), which are made from metal nodes and organic linkers, have demonstrated extensive potential because of their structural tunability, suitable Eg (energy bandgap) energies, and ability to enable efficient charge separation. High surface areas, dual active sites, a variety of pore architectures and tunable functionalities are some of the distinctive structural features of CPs that cooperatively enhance light harvesting, enable photoinduced charge carrier separation and transport, and promote efficient interaction between catalytic sites and water molecules. These characteristics play a major role in upgrading the overall functioning of PWS systems. In this review, we first examine the detailed molecular structure of CPs using a computational approach. Following this, the classification of CPs is presented, with a particular emphasis on different metal-centered frameworks, dimensionality, and porosity, along with modification strategies. These metals are of particular interest due to favourable redox properties, variable coordination geometries, and strong light absorption capabilities. Moreover, the role of different ligands and heterojunction in CPs have been explored. The construction of heterostructures based on these metals facilitates efficient charge separation, which is critical for effective photocatalytic applications. Additionally, the mechanism of photocatalytic OWS (overall water splitting) has been discussed, with an emphasis on the fundamental processes of light absorption, photocarriers separation, and surface redox reactions involved in H2 and O2 evolution. Besides this, we also provided a brief overview of the role of interfacial defects, active sites, and co-catalysts, as well as the unique advantages of CPs in photocatalysis. In addition, recent applications of CP-based photocatalysts for PWS are highlighted, with particular attention to mechanistic insights and performance. Finally, the review summarised by outlining the key disputes and future research directions for advancing CP-based photocatalysts in OWS applications.