Photocatalytic Properties Of G-C₃N₄ Based Catalysts Prepared Via Cold Plasma

Photocatalytic technology has attracted extensive attention and investigation around the world with the serious energy shortage and environment pollution problems,such as photocatalytic water splitting and photocatalytic degradation of organics,and in order to make full use of the infinity solar energy,it is of great significance to find highly efficient and stable catalyst for photocatalytic reaction.g-C₃N₄,as a kind of non-metal semiconductor material,has been applied in photocatalytic reaction system,because of its low cost and stable property,most importantly,g-C₃N₄ is able to response to visible-light irradiation.However,the photocatalytic performance of pure g-C₃N₄ is quite limited,so a modification treatment process is always necessary to improve the photocatalytic activity of g-C₃N₄.Meanwhile,plasma technology has also been applied in the catalyst preparation process as an emerging and potential method.In the first work of this article,we prepared Pt/g-C₃N₄-P through glow discharge plasma reduction method,for comparison,we also used traditional H₂ reduction method and photo-deposition method to prepare Pt/g-C₃N₄-H₂ and Pt/g-C₃N₄-PD.The crystal structure,micro morphology,chemical constitution and optical properties of the obtained samples were investigated by a series of characterization method,including XRD?TEM?SEM?UV-vis DRS?XPS.It turned out that Pt nanoparticles in Pt/g-C₃N₄-P got by glow discharge plasma reduction method were of smaller size at about 2 nm compared with other two reduction method,and the distribution of Pt nanoparticles was much more uniform.We also changed Pt reduction environment during glow discharge plasma reduction method to see whether it could influent Pt reduction process,and it was found that alkaline environment could promote Pt reduction and consequently improving photocatalytic performance.Water splitting experiment was carried out under visible-light???420 nm?irradiation to evaluate the photocatalytic activity of the prepared catalyst samples,the result showed that the H₂evolution rate of Pt/g-C₃N₄-P was 33.9 umol/h,which was 1.38 times and 1.70 times of Pt/g-C₃N₄-H₂ and Pt/g-C₃N₄-PD,respectively.And the sample obtained via glow discharge plasma reduction in alkaline environment,Pt/g-C₃N₄-P-OH,exhibited the best photocatalytic performance with a H₂ evolution rate of 40.0 umol/h.In the second part,we mainly focused on whether we could get g-C₃N₄ nanosheets by directly exposing bulk g-C₃N₄ in DBD plasma.After bulk g-C₃N₄ was treated in DBD plasma,the product was analyzed through XRD?TEM?AFM?XPS?FTIR?UV-vis DRS?PL spectra characterizations to figure out the crystal structure,micro morphology,chemical constitution and structure,according to the results,we found that bulk g-C₃N₄ was successfully exfoliated into g-C₃N₄ nanosheets during DBD plasma treatment process.And the transfer efficiency and life time of photo-induced charge carriers were also improved compared with bulk g-C₃N₄.It was also proved that g-C₃N₄ nanosheets prepared by DBD plasma treatment process was able to split water and degrade RhB under visible-light???420 nm?irradiation.