Study Of Controlling Synthesis And Properties Of G-C₃N₄ Ultra Thin Micro-/Nanomate Rials And Their Composites

In this paper,the composition and crystallinity of graphite phase carbon nitride?g-C₃N₄?during thermal polymerization were systematically studied.On this basis,crystalline/amorphous g-C₃N₄ homojunctions were prepared.In the calcination process of g-C₃N₄,its morphology and photocatalytic activity are regulated via co-doped of S and P elements.Finally,high temperature polymerization of melamine treated with organometallic precursor?Co or Ni?was carried out to prepare Co-or N-loaded N doped bamboo-like carbon nanotubes,which was superior to commercial Pt/C electrode for the performance of catalyzes hydrogen production?HER?,and the cost is only one percent of commercial Pt/C electrodes.At the same time,Ni-loaded carbon nanotubes exhibit excellent selectivity in the field of hydrogenation catalysis.The main contents of this paper are as follows:Controllable synthesis of g-C₃N₄ with different crystallinity and photocatalytic properties of crystalline/amorphous homojunctions.By controlling the heating rate and calcination temperature of the thermal polymerization reaction,crystalline phase and amorphous ultra-thin g-C₃N₄ was prepared,and then crystalline/amorphous homojunction was obtained by seed growth method.It has been found that the composite material has more excellent photocatalytic properties than single crystalline or amorphous phase g-C₃N₄.The homojunction has matching energy level structure and has an interface with close contact,which facilitates the transfer of electrons and holes,reduces the recombination rate of photogenerated electrons and holes,and improves the utilization ratio of the active material,thereby improving photocatalytic performance.Preparation and properties of g-C₃N₄ with controlled morphology via co-doped of S and P elements.By changing the doping amount of S and P elements and the calcination conditions,different morphologies such as nanotubes,tube in tube and nanorod can be obtained respectively.It is also proved by the EPR test that the doping of S and P can introduce defect into the sample.The defect is beneficial to increase the number of active site.The existence of spatially oriented separation of electrons and holes is demonstrated in selective photodeposition experiments,which is also the main reason for the improvement of photocatalytic performance.Photocatalytic performance tests show that the photocatalytic degradation and the performance of photocatalytic hydrogen production of element-doped samples have been significantly improved,especially the hydrogen production performance has increased two orders of magnitude.In this experiment,not only the photocatalytic performance of g-C₃N₄ was improved but also its morphology was enriched.Preparation and properties of N doped bamboo-like carbon tubes with Co or Ni loaded.In the presence of transition metal,tris-triazine ring undergoes structural rearrangement at high temperatures,and because of the reductive nature of C at high temperatures,metal ions were reduced to metallic elements.On the basis of the above two parts,Co or Ni supported N-doped bamboo-like carbon tubes were prepared by controlling the thermal polymerization of melamine in the presence of Co and Ni.It was found by electrochemical tests that Co-loaded sample has better electrochemical performance than Ni-loaded sample,so the Pt nanocluster loading on the Co-loaded carbon tube and the Pt nanoclusters loaded with 0.21%are superior to the commercial Pt/C?Pt loading is 20%?electrode,and the cost is reduced;the Ni-supported carbon tube exhibits excellent selectivity in the catalytic direction of furfural hydrogenation.