Boron-Doped g-C6N6 Layer as a Metal-Free Photoelectrocatalyst for N2 Reduction Reaction

Ammonia is one of the most important industrial chemicals due to its wide application in various fields. However, its synthesis requires heavy energy consumption and harsh reaction conditions. Here, density functional theory is employed to determine the free energy profile for the nitrogen reduction reaction on the boron-decorated, optically active graphitic carbon nitride (B@g-C6N6) monolayer. We find that the rate-determining step for the N-2 reduction to NH3 over B@g-C6N6 is the first reduction step, through the enzymatic mechanism, with a record low onset potential of -0.03 V. Importantly, doped g-C6N6 can not only effectively capture and activate N-2 molecules via an "acceptance-donation" process but also significantly enhance the visible-light absorption. Low onset potential, strong visible light absorbance, amiable synthesis, and high stability make B@g-C6N6 a promising photoelectrocatalyst for N2 fixation, which offer a potential pathway for advancing sustainable NH3 production. may