Ni And ReS₂ Doped Graphite Phase Carbon Nitride To Reduce CO₂

Graphite phase carbon nitride(g-C3N4)is a new type of organic two-dimensional semiconductor material.It has a good application prospect in the field of photocatalysis due to its wide range of raw materials,visible light response and superior band edge position.In this thesis,the combination of theoretical calculation and experiment is used to carry out the photocatalytic reduction of CO2 by g-C3N4.In this paper,the DMol3 software package in the calculation software of Materials Studio was used to simulate the CO2 reduction of two isomers of g-C3N4,triazine-based g-C3N4(t-g-C3N4)and heptazine-based g-C3N4(h-g-C3N4).The mechanism to CO,and the ability to reduce CO2 in pure phase g-C3N4 by loading the transition metal Ni.On this basis,the reduction mechanism of pure phase and Ni-loaded t-g-C3N4 and h-g-C3N4 to reduce CO2 to CH4 was studied.It is thus concluded that h-g-C3N4 is easier to reduce CO2 than t-g-C3N4,and can further enhance its ability to reduce CO2 after Ni loading.Further,we studied the reduction mechanism of CO2 reduction to CH4 by means of experiments and theoretical calculations.Experimentally,t-g-C3N4 and h-g-C3N4 were synthesized by a salt melting method and a thermal polymerization method.The experiment of CO2 reduction was then carried out under the conditions of a light intensity of 0.35 W/m2.It was found that h-g-C3N4 still has stronger catalytic activity.Furthermore,by studying the mechanism of CO2 reduction to CH4 reaction pathway,it was found that h-g-C3N4 has more superior photocatalytic ability to reduce CO2.Based on the existing experiments and calculation results,we screened h-g-C3N4 as a base material for CO2 reduction and enhanced its inherent photocatalytic reduction of CO2 by doping with ReS2.The experimental results show that h-g-C3N4 has stronger photoelectric response and photocatalytic ability to reduce CO2 after doping with ReS2.Through the above studies,we found that the use of hg-C3N4 as a substrate for its modification to reduce CO2 can effectively enhance its own photocatalytic reduction of CO2,so the h-g-C3N4 is a good substrate of photocatalyst that could have wide application prospects in the field of photocatalytic reduction of CO2.