The rise of two-dimensional covalent C3N5: a molecular perspective

Abstract

C₃N₅ not only shares comparable thermal and chemical stability with C₃N₄ but also demonstrates an improved π network, a narrower band gap (ranging from 1.76 to 2.5 eV), and a richer nitrogen active site. These characteristics grant C₃N₅ excellent electronic and optical properties, making it a promising material in the field of photocatalysis and energy-related applications. To facilitate a comprehensive understanding of C₃N₅ from a molecular perspective, this review categorizes all existing C₃N₅ structures into five types, highlighting the structural features and subtle differences in band gaps among them. The self-condensation synthesis for C₃N₅ is summarized and classified based on six different precursors. Heteroatom doping of C₃N₅ is discussed, including non-metal elements such as S, B, and P, as well as metal elements such as K, Co, and Fe. According to the synthetic strategies, the compositing process of C₃N₅ with other functional materials is classified as in situ synthesis of C₃N₅ for composites, C₃N₅-templated synthesis of composites, and post-synthetic mixing for composites. This review offers an exhaustive overview of the ongoing research advancements concerning pure C₃N₅, doped C₃N₅ and C₃N₅-based composites at the molecular level, which will facilitate the structural design and potential applications for C₃N₅.