Unlocking the Potential of Carbon Nitride (CxNy) Electrocatalysts in Hydrogen Evolution, Oxygen Evolution and Overall Water Splitting

Abstract

Electrocatalytic water splitting with carbon nitride (CxNy) materials has gained significant interest, driven by extensive research validating their synthesis, structure, and applications. Among various CxNy stoichiometric ratios, graphitic carbon nitride (g-C3N4) stands out as the most stable configuration and is extensively studied in the literature. However, other CxNy structures like g-CN, C2N, C3N5, and C9N4 have been booming recently as well by exploration of their greatness. Recent progress of CxNy-based electrocatalysts in hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting (OWS) has been examined meticulously. More emphasis has been placed on exploring the synthesis-structure-performance and simulate-structure-performance relationships of CxNy electrocatalysts in experimental and computational studies, respectively. This review outlines a clear framework for unifunctional CxNy electrocatalysts in HER and OER, focusing on recent advancements in (1) defect engineering, (2) structural engineering, and (3) hybridization. The research on bifunctional CxNy electrocatalysts is highlighted and explored through two main approaches: intrinsic and extrinsic modifications. Finally, the strategies and perspectives for creating novel highly efficient CxNy electrocatalysts for HER, OER, and OWS are analyzed. This review aims to inspire researchers to incorporate computational methods into experimental studies for developing highly efficient bifunctional CxNy-based electrocatalysts.