Selective charge transfer to dioxygen on KPF6-modified carbon nitride for photocatalytic synthesis of {H2O2} under visible light
By Kim, Sujeong; Moon, Gun-hee; Kim, Hyejin; Mun, Yeongdong; Zhang, Peng; Lee, Jinwoo; Choi, Wonyong
Published in Journal of Catalysis
2018
Abstract
Photochemical production of {H2O2} through {O2} reduction has been proposed as an alternative method of solar energy storage. A carbon nitride (CN) photocatalyst was selected for this purpose. The incorporation of {KPF6} into the {CN} structure greatly enhanced the apparent quantum yield (AQY) of {H2O2} production in the {UV} and visible light region. The {AQY} of KPF6-modified {CN} was measured to be 35.9% and 24.3% under monochromatic irradiation at 370 and 420 nm, respectively, which are 8.3 and 26.1 times higher than for bare CN. The KPF6-enhanced activity is ascribed to several factors including (i) enhanced absorption of {UV} and visible light, (ii) higher charge carrier density, (iii) retarded radiative recombination of charge pairs, (iv) highly selective two-electron transfer to O2, and (v) hindered photodecomposition of in-situ generated H2O2. The markedly high selectivity of KPF6-modified {CN} toward the two-electron reduction of {O2} (leading to H2O2) was demonstrated in comparision with other photoreductive conversions such as the reduction of polyoxometalate (POM ? POM?), hexavalent chromium (CrVI ? CrIII), {CCl4} (dechlorination), and protons (H2 production). This study developed a simple method of efficient production of {H2O2} using visible light, which could be utilized for a variety of applications that employ {H2O2} as a solar fuel or a green oxidant.