A review on the effects of doping elements on the properties and applications of lignin-based carbon materials

Abstract

Lignin, which consists of about 30% organic carbon, is considered as one of the most ample biopolymers in the world. The conversion of lignin into materials with higher added value, such as porous carbon, is a good example of a green circular economy. Lignin-based carbon materials have excellent properties, which are greatly enhanced by the doping of elements. In this paper, we start with the structure and composition of lignin, and after that, there is a systematic review of the performance and applications of lignin-based doping with non-metallic elements (O, N, S, P, etc.) and metallic elements (Cu, Co, Ni, Fe, Mn, etc.) to prepare porous carbon electrode materials. Finally, the near-term challenges and prospects of lignin-based carbon materials for progressive energy storage devices are presented. On the basis of the review, a purposeful summary of the preparation methods of each doping atom with the influence of different types of lignin is presented. At the same time, the advantages and disadvantages of each doping atom as well as the doping methods are dissected. The aim is to provide theoretical guidance for the design, preparation and performance optimisation of heteroatom-doped lignin-based carbon materials for future practical applications such as supercapacitors, adsorbents and catalysts.