| Graphitic carbon nitride(g-C3N4)has attracted great attention in the field of photocatalysis and photoelectric conversion due to its unique photoelectric chemical properties and excellent structural stability.Compared to the bulk g-C3N4 prepared by thermal polymerization of N-rich precursor,modified g-C3N4 with nano-structure can overcome the drawbacks such as low specific surface,ineffective charge separation and limited light absorption.However,developing an effective and environment-friendly strategy to modify the microstructure and morphology of g-C3N4 is challenging because the most common template methods are high-cost,high-risk intensive as well as tedious.In this paper,we proposed a bottom-up strategy to control the morphology and microstructure of g-C3N4,and the g-C3N4 showed an excellent catalytic activity and universality in photocatalytic degradation of organic pollutants.The specific research content is as follows(1)A conjunct strategy of the dynamic gas template method and the precursor self-assembly method was proposed.With moderate ammonium chloride as inducer,the hydrothermal pretreatment allowed melamine precursor transforming into a nano-size regular supramolecule.After thermal polymerization process,we obtained mesoporous ultra-thin g-C3N4 nanosheets.The structure characterization and photoelectric properties of the product were further explored.The structure results showed that,the ultra-thin g-C3N4 nanosheet has a large specific surface area(58.6m2/g)with thickness of about 1.5nm.The photoelectric tests showed that g-C3N4 nanosheet has a superior charge carrier migration and separation efficiency.The high specific surface area is beneficial to expose more active sites and accelerate the adsorption and reaction process in the degradation process.More importantly,the ultra-thin lamellar structure can shorten the carrier migration distance,which is beneficial for the photogenic carriers to migrate to the sample surface and participate in the reaction effectively and quickly,so as to reduce the carrier recombination rate and greatly improve the photocatalytic activity.Ultra-thin g-C3N4 nanosheet shows excellent photocatalytic degradation of RhB,and the degradation rates reach 0.135min-1,which is 15 times higher than that of Bulk g-C3N4(2)A H2SO4-assisted precursor self-assembly strategy was proposed.Tubular g-C3N4 is prepared in situ by annealing a melamine-cyanurate supramolecular array,which is conducted through a H2SO4-assisted precursor self-assembly strategy.The optimal amount of H2SO4 was determined as 2mL(melamine:4g)by a control variable experiment.The band structure and photoelectric properties of the product were further explored.The carrier density(ND)of tubular g-C3N4 was determined to be 9.4×1018,which is 3 times higher than that of BCN.The results of XPS,DRS,and PL show that the N2c defect,nano size,and 1D structure might boost the transmission of the photogenerated carriers and further suppress charge recombination.The study of the band structures shows that tubular g-C3N4 had a wider band gap and a large offset(-0.45eV)of the CB positions which is expected to deliver a better photo-oxidation activity,and·O2-was determined to be the main active oxidation species for the degradation.Benefiting from the high specific surface area(92.04m2/g)provided by the hierarchical pores and the hollow structure,Tubular g-C3N4 shows excellent photocatalytic degradation of MB and TC,and the degradation rates reach 0.0265 min-1 and 0.0110 min-1,respectively,which are 3 and 7 times higher than that of Bulk g-C3N4. |
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