Bi, K co-doped graphitic phase carbon nitride for efficient photocatalytic H2O2 production

Herein, Bi, K co-doped g-C3N4 was prepared by co-thermal polymerization of a mixture of potassium nitrate, bismuth nitrate, and melamine. The obtained Bi, K co-doped g-C3N4 possesses more negative conduction and valence band positions that can, to some extent, enhance photocatalytic performance by lowering the energy barrier of redox reactions and by enhancing electron absorption capacity. Additionally, the pyrolysis process of the potassium nitrate and bismuth nitrate has a considerable impact on the formulation of the morphology of g-C3N4, generating a porous lamellar-structure with nitrogen defects, resulting in increased oxygen adsorption and utilization capacity. These synergetic effects ultimately give rise to successful improvement of the photocatalytic performance of g-C3N4, with the maximum hydrogen peroxide (H2O2) production efficiency reaching 1.45 mmol g−1h−1 (O2, AM 1.5). The Bi3.6K3-CN exhibited superior cycling stability and photocatalytic activity for H2O2 production, i.e., 1.21 mmol/L after 3 h of visible-light irradiation, 57 times higher than pure g-C3N4.