Cyano-rich carbon nitride with tunable n → π* electronic transition for enhanced broad-spectrum photocatalytic H2O2 production

The development of photocatalysts that effectively utilize broad-spectrum light, which occupies a primary percentage of the solar spectrum, remains a great challenge. In this paper, we propose a salt-assisted method mediated by sodium oxalate template to achieve both oxygen doping and formation cyano group defects in carbon nitride materials (CNNO). The simultaneous introduction of oxygen and cyano defects not only induced the distortion of the heptazine structure thus effectively activated the n → π* electron transition, but also can achieve the qualitative changes of broad-spectrum photocatalytic H2O2 production from "0″ to "1" (λ ≥ 700 nm) of CNNO, which has rarely been reported in single photocatalysts. DFT calculations show that the electronic structure of CNNO is rearranged to favor O2 adsorption as well as the formation of the key intermediate OOH*. The present work achieves the co-optimization of electronic structure and light absorption of CN through the synergistic effect of oxygen doping and the construction of cyano defects, which provides a new strategy for the design and synthesis of CN materials that effectively utilize sunlight.