Abstract
The nanocomposite preparation procedure plays an important role in achieving a well-established heterostructured junction, and hence, an optimized photocatalytic activity. In this study, a series of g-C3N4/ZnO nanocomposites were prepared through two distinct procedures of a low-cost, environmentally-friendly, in-situ fabrication process, with urea and zinc acetate being the only precursor materials. The physicochemical properties of synthesized g-C3N4/ZnO composites were mainly characterized by XRD, UV–VIS diffuse reflectance spectroscopy (DRS), N2 adsorption-desorption, FTIR, TEM, and SEM. These nanocomposites’ photocatalytic properties were evaluated in methylene blue (MB) dye photodecomposition under UV and sunlight irradiation. Interestingly, compared with ZnO nanorods, g-C3N4/ZnO nanocomposites (x:1, obtained from urea and ZnO nanorods) exhibited weak photocatalytic activity likely due to a “shading effect”, while nanocomposites (x:1 CN, made from g-C3N4 and zinc acetate) showed enhanced photocatalytic activity that can be ascribed to the effective establishment of heterojunctions. A kinetics study showed that a maximum reaction rate constant of 0.1862 min-1 can be achieved under solar light illumination, which is two times higher than that of bare ZnO nanorods. The photocatalytic mechanism was revealed by determining reactive species through adding a series of scavengers. It suggested that reactive ●O2− and h+ radicals played a major role in promoting dye photodegradation.
Highlights
Solar energy is believed to be the most abundant source of sustainable and clean energy [1]
We explore here the effect the synthesis procedure has on the physiochemistry, photoelectrochemistry (PEC) properties, and photodegradation activities of g-C3N4/ZnO nanocomposites (x:1 vs. x:1 CN) prepared by an in-situ calcination route
The nanocomposites prepared with g-C3N4 as the starting precursor are denoted as x:1 CN
Summary
Solar energy is believed to be the most abundant source of sustainable and clean energy [1]. Among well-known semiconductor photocatalysts, ZnO is promising because of its remarkable properties, such as physicochemical/thermal stability, low-cost, high redox potential, and electron mobility [10,11,12]. Extensive attention has been made to enhance the photocatalytic activity and stability of ZnO based photocatalysts via heteroatom doping [13,14,15,16], novel metal deposition [17,18], or coupling with narrow band gap semiconductors [19,20,21]. A light non-metal semiconductor graphitic carbon nitride (g-C3N4) has attracted much interest due to its unique electronic structure, remarkable chemical stability, visible light activity, and cost-effective features [22,23]. It still remains a challenge to obtain highly stable and active g-C3N4 based photocatalysts
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