Preparation And Modification Of Porous Carbon Nitride And Its Photocatalytic Performance

Energy and environment issues have become two major problems restricting the sustainable development of human society.We urgently need to develop an environmentally friendly,green and sustainable means to solve energy and environment issues.Photocatalytic technology uses solar energy to degrade organic matter,and can also convert solar energy to hydrogen energy.It is considered to be an effective method to solve energy and environmental problems from the root.Photocatalyst is the core of photocatalytic technology.To promote the progress of photocatalytic technology,we must start by developing efficient and stable catalysts.Graphitic carbon nitride has attracted wide attention due to its advantages such as easy preparation,stable chemical properties,and suitable band gap.However,graphitic carbon nitride also have some shortcomings that cannot be ignored,such as its inability to make full use of the energy of visible light,its small specific surface area,and its high electron-hole recombination rate.In this paper,a series of porous carbon nitride catalyst MCAU was prepared and its hydrogen production activity was evaluated.The surface was modified with red phosphorus to prepare an RP/MCAU catalyst and its degradation activity to rhodamine-B was evaluated.First,using a simple supramolecular thermal polycondensation method,a series of porous carbon nitride catalyst MCAU was prepared by introducing uracil,and the photocatalytic hydrogen production performance of the catalyst was explored under visible light irradiation.The experimental results show that the catalyst MCA-U2prepared by introducing the optimal amount of uracil has a hydrogen production rate of 2352?molg^-1h^-1,which is 3.95 times that of the MCA(596?molg^-1h^-1)without the introduction of uracil,which is ordinary g-C₃N₄(83?molg^-1h^-1)Of 28.34 times.Various analyses show that the introduction of uracil modifies the position of the valence band and suppresses the electron-hole recombination,which is beneficial to the improvement of photocatalytic hydrogen production performance.Cycle experiments show that the catalyst has better photocatalytic stability.Secondly,red phosphorus modified carbon nitride catalyst RP/MCAU was prepared by reducing phosphorus triiodide under liquid phase conditions.Various characterization results show that the modification of red phosphorus increases the light absorption range of the catalyst and inhibits electron-hole recombination.Degradation of Rhodamine-B under visible light irradiation showed significantly enhanced photocatalytic activity.The reaction rate constant of 10%RP/MCAU was 0.468 min^-1,and the activity was greatly improved compared with MCAU(0.018 min^-1).Through free radical capture experiments,the experimental results show that the main active species for the degradation of rhodamine-B by the catalyst 10%RP/MCAU are superoxide radicals and holes.At the same time,a cyclic experiment was performed,and the catalyst showed good photocatalytic stability.