Preparation And Photocatalytic Properties Of G-C₃N₄/Metal Sulfide Composites

In recent years,environmental pollution and energy shortages have attracted more and more attention,and it is imperative to seek sustainable development of clean energy.As a way to effectively use solar energy,semiconductor photocatalysis technology has unique advantages such as green,low-carbon and environmental protection,and has great application value in the field of environment and energy.Among them,graphite-phase carbon nitride g-C₃N₄（GCN）,as a highly visible light-responsive photocatalyst,has received widespread attention.However,due to its low specific surface area,the narrow utilization range of visible light and the rapid recombination of photo-generated electron-hole pairs restrict its application.In response to these problems,this article uses non-metallic element doping,solid phase reaction method,hydrothermal method and other methods to prepare oxygen-doped graphite phase carbon nitride/cadmium sulfide（OCN/CdS）and molybdenum disulfide/oxygen-doped graphite Phase carbon nitride（Mo S₂/OCN）two composite photocatalysts,through the photoelectrochemical performance test and photocatalytic degradation of pollutants and other experimental research,the following main results have been obtained:1.Using melamine and oxalic acid as raw materials,a porous oxygen-doped graphite phase carbon nitride（OCN）with a controllable morphology was prepared by a solid-phase reaction method.It was found that the doping of oxygen atoms significantly changed the electronic band structure of GCN,Shortening its band gap width and exhibiting excellent visible light response.Under visible light irradiation,10 mg OCN-0.4 can achieve 76.2%degradation of 40 m L of 10mg/m L rhodamine B（Rh B）aqueous solution within 30 minutes.The quasi-first order kinetic constant k is 2.59 times that of bulk GCN,and the photocurrent response is 2.78 times that of GCN photocurrent.2.A one-step hydrothermal method was used to synthesize OCN/CdS composite photocatalysts with different composition ratios.Among them,OCN/CdS-4（composition ratio CdS/OCN=60%）showed excellent catalytic performance.After visible light irradiation At 30minutes,the degradation of Rh B by OCN/CdS-4 reached 96.2%,and the catalytic constant reached 0.158,which was 24.38 times that of GCN,3.77 times that of OCN,and 6.99 times that of CdS.It was applied to the catalytic degradation of MB.After OCN/CdS-4 was irradiated with visible light for 25 minutes,the degradation of methyl blue（MB）reached 93.9%,while the catalytic constant of OCN/CdS reached 0.084,which was 2.76 times the catalytic constant of GCN.In the electrochemical performance test,the peak photocurrent of OCN/CdS-4 was6.38 times that of GCN and 2.7 times that of OCN,respectively.Too much or too little CdS will reduce the current density.O2-and h+are the main active species for photocatalytic degradation of organic pollutants.3.Using the hydrothermal method to compound Mo S₂ and OCN in different proportions,it is found that the introduction of Mo S₂ does not affect the lattice structure and functional groups of OCN.Under simulated sunlight,6%Mo S₂/OCN showed excellent photoelectrochemical performance,and the peak photocurrent was 8.05 times that of GCN and3.04 times that of OCN;under visible light irradiation for 25 minutes,its degradation of Rh B reached 81.9%.The catalytic constant reaches 0.06752,which is 9.46 times that of GCN;the degradation of MB reaches 82.6%,and the catalytic constant reaches 0.05038,which is 1.72times that of GCN,showing excellent photocatalytic performance.