Photocatalytic Production of Hydrogen Peroxide by pg-C3N4/CQDs Composite under Visible Light

Abstract

Compared with the traditional anthraquinone method, photocatalytic production of hydrogen peroxide (H2O2) has the advantages of clean and environmental protection, mild conditions, and low power consumption. Graphite carbon nitride (g-C3N4) is a promising photocatalyst for H2O2 production. However, owing to its small specific surface area, narrow light response range, and easy recombination of photogenerated electron-hole, the efficiency of H2O2 production is relatively low. In this paper, porous graphite carbon nitride (pg-C3N4) was synthesized by using melamine hydrochloride as precursor, and carbon quantum dots (CQDs) were loaded on its surface to prepare pg-C3N4/CQDs composite photocatalyst. The structure, morphology, and optical and electrochemical properties of the samples were characterized by XRD, TEM, UV-Vis, TP, PL, and so on. The catalyst has a large specific surface area. At the same time, the optical characteristics of CQDs and its good properties of capturing and transferring electrons greatly improve the light response range of the composite photocatalyst (even reaching the near-infrared region), and effectively inhibit the recombination of photogenerated electron-hole. In the H2O2 production experiment under the visible light, pg-C3N4/CQDs showed higher photocatalytic H2O2 production activity. After reaction for 5 h, the H2O2 concentration reached 0.301 mmol/L, which was 27 and 13 times those of g-C3N4 and pg-C3N4, respectively. Finally, the possible mechanism of photocatalytic H2O2 production by pg-C3N4/CQDs was proposed through free radical capture experiment.

Keywords

• porous graphite carbon nitride
• carbon quantum dots
• visible light
• photocatalytic production of hydrogen peroxide