Abstract

The development of innovative materials is crucial for advancing sustainable energy solutions by enhancing energy harvesting, conversion, and storage technologies. Flexible and lightweight substrates such as paper, cloth, and polyimide films, when integrated with laser-induced graphene (LIG) and laser-induced reduced graphene oxide (LIrGO) doped with metals, exhibit exceptional conductivity, mechanical robustness, and sensitivity. These attributes make them ideal for solar energy capture, hydrogen fuel cells, and high-performance supercapacitors. Substrates like paper's natural porosity and biodegradability also offer sustainable pathways for eco-friendly device fabrication, supporting the transition to a decarbonized energy future. Recent innovations, such as the growth of cobalt oxide (Co₃O₄) and boron-doped LIG (BLIG) directly on polyimide-coated paper and fabric, have significantly improved electrical and mechanical properties. These advancements are particularly beneficial for energy storage and wearable sensors. Metal-enhanced LIG composites incorporating boron, cobalt, silver, or gold exhibit remarkable conductivity and mechanical stability. In biosensing, in situ deposition of silver and gold with LIG enables simplified fabrication processes and highly sensitive detection capabilities, making these composites suitable for biomolecule detection in wearable health monitors and diagnostic devices. For energy storage, Fe₃O₄-based transition metal oxide (TMO) composites demonstrate excellent charge retention, cycling stability, and robust pseudocapacitive behavior, making them suitable for batteries and supercapacitors. BLIG enhances ion mobility through additional capacitive sites, boosting charge storage for energy-dense applications. Reduced graphene oxide (rGO) produced on biodegradable substrates supports eco-friendly, disposable devices, including supercapacitors and electrochemical sensors. Biopolymer-treated rGO films offer low resistance and high conductivity, which are vital for fuel cells and energy sensors. These advancements in flexible materials and conductive coatings drive sustainable, high-performance solutions for energy applications, wearable electronics, and environmental sensing, shaping a future of eco-friendly and efficient energy technologies.