Lignite has emerged as a critical material in contemporary energy portfolios, particularly in electricity generation. However, this work explores lignite's potential beyond conventional uses, exploring on its energy conversion applications. In a pioneering move, lignite samples have been directly utilized as materials for photothermal conversion applications, along with a description of their geochemical features, such as sulfur compositions, forms, and microscopic characteristics. Among the twenty lignite samples that were geologically studied, two sulfur-rich samples (CS-1 and CS-2) were chosen to explore their photothermal conversion performance. The powder-XRD diffraction patterns of CS-1 and CS-2 reveal the presence of the hexagonal phase of carbon C