Preparation Of Porous Carbon Nitride And Mechanism Of Visible Light Catalysis Enhancement

The energy shortage and environmental pollution caused by the rapid industrial development cannot be ignored,and it is extremely challenging to solve these two problems at the same time.Graphitic carbon nitride（g-C₃N₄）has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation.This is due to its appealing electronic band structure,high physicochemical stability,and“earth-abundant”nature.However,practical applications are still hindered by several obstacles and shortcomings of bare g-C₃N_4,including the high recombination rate of charge carriers,low electrical conductivity,and the lack of absorption above 460 nm.The hard template method is considered to be an effective method to tailor the structural properties of the g-C₃N₄material by optimizing the nanostructure of the g-C₃N₄ material.（1）Porous g-C₃N₄（m Cag-C₃N₄）was successfully prepared by using calcium carbonate（CaCO₃）as the template and dicyandiamide（DCDA）as the nitrogen-rich precursor.The as-prepared photocatalysts were characterized by SEM,XRD,FT-IR,UV-vis,XPS,PL,BET and electrochemical workstation.The photocatalytic activity was evaluated by using rhodamine B（Rh B）as a target organic pollutant.The experimental results show that the optimal amount of CaCO₃ particles is 250 mg.Compared with the original g-C₃N₄,the BET surface area of250Cag-C₃N₄ is increased by 6 times,the photocatalytic activity is increased by 2 times,and the degradation rate of Rh B is 94.5%.The improvement of the photocatalytic performance of250Cag-C₃N₄ is mainly attributed to the narrowing of the band gap,the widening of the light response range,the enhancement of the light absorption capacity,and the suppression of the photo-generated carrier recombination rate.（2）Porous g-C₃N₄（m Sig-C₃N₄）was successfully prepared by using colloidal silica（Si O₂）as the template and DCDA as the nitrogen-rich precursor.The as-prepared photocatalysts were characterized by SEM,XRD,FT-IR,UV-vis,XPS,PL,BET and electrochemical workstation.The photocatalytic activity was evaluated by using Rh B as a target organic pollutant.The experimental results show that the optimal amount of Si O₂ particles is 2000 mg.Compared with the original g-C₃N₄,the BET surface area of 2000Sig-C₃N₄ is increased by 15 times,the photocatalytic activity is increased by 3 times,and the degradation rate of Rh B is 98.1%.The improvement of 2000Sig-C₃N₄ photocatalytic performance is mainly attributed to the increase of specific surface area,which will improve the adsorption performance of dyes,provide more reactive sites,shorten the migration path of photogenerated carriers,and inhibit the photo-generated carrier recombination rate.