화학적 산화 처리를 통한 광수전해용 Pt/g-C3N4 촉매 성능 개선

Abstract

In this study, platinum (Pt)-containing graphitic carbon nitride (g-C3N4) catalysts modified using simple chemical oxidation of g-C3N4 were prepared for the first time, and the catalysts were applied to photocatalytic hydrogen evolution tests. The hydrogen production rates of the chemically oxidized Pt/g-C3N4 photocatalysts (2,471.7 and 3,640.8 µmol g−1 h−1) were found to be at least 5 times higher than those of bulk Pt/g-C3N4 (429.3 and 728.8 µmol g−1 h−1). During the Pt photodeposition on the g-C3N4 surface, the chemically oxidized g-C3N4 with a more negatively charged surface and the functional groups maintained the high ratio of Pt2+/Pt0 among the Pt nanoparticles. The higher proportion of Pt2+ sites on the chemically oxidized g-C3N4 enhanced the hydrogen evolution rate by suppressing the reversible reaction route of H2 to 2H+. In addition, the chemically oxidized g-C3N4 with oxygen-containing functional groups improved the separation efficiency of photoexcited charges over Pt/g-C3N4. On the basis of the enhanced hydrogen production thanks to the above-mentioned properties of chemically oxidized g-C3N4, different Pt loading methods such as chemical reduction, hydrogen reduction, and photoreduction on chemically oxidized g-C3N4 were studied to investigate the support’s properties on Pt deposition processes. Among different Pt loading methods, the hydrogen reduction method gave the chemically oxidized Pt/g-C3N4 with the highest photocatalytic hydrogen production, which could be explained by the synergy of high ratio of Pt2+/Pt0, high Pt nanoparticles distribution, and efficient photoinduced charge transfer from chemically oxidized g-C3N4 onto active site Pt.