Research Of Carbon Doped ZnO Thin Films For Visible-light Driven Conversion Of Nitrogen To Ammonia

At the beginning of the 20th century,Haber-Bosch developed an iron based catalyst for the production of ammonia.As an important inorganic substance,ammonia has been widely used and played an important role in national construction.As semiconductor photocatalyst,ZnO has many advantages,such as high catalytic activity,innocuity and low cost.It is widely used in sewage treatment,air purification and other fields.It is a promising photocatalytic material.However,as a photocatalyst,there are many defects in ZnO:Large band gap(3.37 eV);only can absorb the ultraviolet light and cannot make full use of solar energy;the recombination of photogenerated electron and hole electrode occurs easily.At present,photocatalyst catalyst for the synthesis of ammonia are powder,it is reunion in the fluid easily and recycling low.At the same time,the disorderly reflection of light leads to low utilization of light energy,which is not conducive to the application of photocatalytic N2 gas synthesis of ammonia.In this thesis,carbon-doped ZnO thin films were prepared on a plane glass surface by magnetron sputtering dual-target co-sputtering method.We discussed the influence of carbon target sputtering power,gas pressure and other conditions on the phase,film thickness,chemical valence and elemental content of the films.The crystal forms,absorbance,element valence of carbon-doped ZnO films were characterized by XRD,UV-Vis and XPS.In the 300W xenon lamp conditions,the performance of photocatalytic N2 gas ammonia synthesis was studied.The results show that the optimum doping amount of carbon is 1.03%.At this time,we obtained the maximum yield of nitrogen in visible light catalytic nitridation.The quantum dots size is 4nm and the spacing of crystal planes of 0.21nm in carbon-doped ZnO thin films.The films can absorb visible light.At the same time,the carbon in the ZnO lattice increases the position of the ZnO conduction band and enhances the reduction ability of the excited electrons.When the amount of carbon doping is 1.03%,the yield of ammonia nitrogen is 5.15*10-4mol·h-1'·cm-2.In order to increase the surface area of the plane glass,micro-sized spherical pits are etched on the surface of the glass substrate by the reverse micellar micro-ball etching technology,and the glass surface of the micrometer pit is sputtered and coated.Sputtering coating process,the sputtering product will enter the micron pit,the film "embedded"within the substrate,thereby greatly enhancing the film to participate in the photocatalytic reaction of the contact area.The results show that the diameter of micropores in glass pit is 0.5-2?m and the pit depth is 100-500nm.Compared with the film on the plane glass surface,the ammonia nitrogen yield of the films on the surface of the micron pit glass increased to about 1.4 times in the photocatalytic ammonia synthesis experiment and the film-based bonding strength increased more than two times.