Colorful Silver/Carbon Nitride Composites Obtained by Photoreduction
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doi: 10.1007/s40242-020-0349-y
Article
Colorful Silver/Carbon Nitride Composites Obtained by Photoreduction MENG Peng and XU Jingsan* School of Chemistry and Physics, Science and Engineering Faculty, Queensland University of Technology, Brisbane, QLD 4000, Australia Abstract The Ag+ photoreduction by graphitic carbon nitride(g-CN) materials in a high concentration of Ag+ solution is reported, and a series of colorful Ag/g-CN composites is prepared and characterized. The chromatic change correlates to the carbon nitride materials synthesized at different heating temperatures(CNT, where T means heating temperature), taking advantage of the different photocatalytic activities of different CNT. The mechanism beneath this phenomenon is attributed to two factors: the particle size of Ag NPs and the coordinate effect of Ag NPs on CN T sheets. Interestingly, the multicolors of Ag/g-CN composites display only on the CNT materials synthesized from heating melamine-cyanuric acid precursor, but not on the CNT from heating pure melamine. The color of the as-prepared Ag/g-CN composites can endure the corrosion of HNO3 and ethanol, which shows a good chemical stability and may hint its application as chromophores. Keywords Graphitic carbon nitride(g-CN); Photoreduction; Silver/g-CN composite
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Introduction
photocatalysts]. The deposition of a large quantity of metal ions on g-CN sheets, however, remains unexplored, which is likely because it is not a good idea in terms of photocatalysts. In this paper, we reported a chromatic change phenomenon in a series of Ag/g-CN composites, by photo-reducing a large quantity of Ag+[over 500%(mass ratio) to the g-CN] on g-CN sheets which were obtained at varying temperatures(denoted as CNT, T means calcination temperature ranging from 450 °C to 550 °C). The color of Ag/g-CN composites could vary from pink to yellow and grey-blue depending on the CNT. Particle-size analysis indicated that the particle sizes of the photo-reduced Ag NPs on different CNT are various, which should play a role in the chromatic change. Interestingly, we found that the chromatic change only occurred on CNT synthesized from a specific precursor. The colors of Ag/g-CN composites were nitric acid and ethanol resisted, demonstrating the composites are chemically stable, which might hint its potential application as chromophores.
In the past decade, graphitic carbon nitride(g-CN) as a metal-free organic polymeric photocatalyst has attracted intensive research interest[1—8]. Among many methods that have been developed for the synthesis of g-CN, the simplest is via pyrolysis of nitrogen-rich precursors[1,8,9]. And the precursors can be roughly classified into two groups: monomers(urea, melamine, etc.) and supramolecular complexes[melamine-cyanuric acid (CAM)]. It is also well documented that g-CN materials obtained from different species of precursors show various photocatalytic performance[10—15]. Besides the species of precursor, the calcination conditions, for instance, temperature, also can be used to tailor the ph
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