Advances in Carbon Nitride-Based Materials and Their Electrocatalytic Applications

As a group of large-surface-area nonmetal materials, polymeric carbon nitride (CxNy) and its hybrid structures are nowadays of ever-increasing interest for use in energy devices involved in energy conversion and storage, offering low expenses and facile production processes. With the growing requirement for clean and renewable energy generation and storage systems, progress in the replacement of expensive noble-metal catalysts with CxNy-based materials as efficient electrocatalysts has expanded considerably, and the demand for these materials has increased. The modified CxNy architectures are beneficial to electrocatalytic applications, improving their moderate electrical conductivities and capacity loss. The present review strives to highlight the recent advances in the research on the aforementioned identities of CxNy-derived materials and their structurally modified polymorphs. This review also discusses the use of CxNy-based materials in fuel cells, metal–air batteries, water splitting cells, and supercapacitor applications. Herein, we deal with electrocatalytic oxidation and reduction reactions such as hydrogen evolution, oxygen evolution, oxygen reduction, CO2 reduction, nitrogen reduction, etc. Each device has been studied for a clearer understanding of the patent applications, and the relevant experiments are reviewed separately. Additionally, the role of CxNy-derived materials in some general redox reactions capable of being exploited in any of the relevant devices is included.