Controllable Synthesis And Catalytic Hydrogen Production Of 2D Porous Titanium Dioxide Nanosheets

The development of hydrogen energy is an effective way to cope with the energy crisis,and direct photocatalytic hydrogen production by semiconductor is the simplest method of hydrogen production.In addition,electrocatalytic hydrogen production is also an effective way to obtain hydrogen energy.TiO₂ is the first photocatalyst to achieve photocatalytic water decomposition.After years of research,it has been found that TiO₂ can also be used as an electrocatalyst to achieve electrocatalytic hydrogen evolution.Therefore,this paper will study thesis to synthesize TiO₂ nanosheets with porous structure by template method,and then fulfill high-efficiency photocatalytic and electrocatalytic water decomposition hydrogen production through metal element loading.The main research contents are summarized as followed:In chapter one,the principles of semiconductor photocatalytic and electrocatalytic technology,the main applications and ongoing researches will be briefly presented.Then several common micro-structure modulation approaches and the impact of such modulations on catalytic performance will be introduced.In chapter two,we first prepare anatase phase TiO₂ by using g-C₃N₄ as a template and introduce Ti as a precursor.It is confirmed by TEM and adsorption experiments that we successfully synthesized porous TiO₂ nanosheets with large surface areas.In chapter three,the photocatalytic activity of TiO₂ for water-splitting hydrogen production is studied.First,the Pt element is loaded,the percentage of which is only 0.6 wt%.It is found that the load of Pt broadens the light absorption range of TiO₂ to the visible light region through UV test.The reason is that the loading of Pt promotes the separation of photogenerated carriers to a certain extent.At the same time,Pt is the active site for hydrogen production.These two reasons cause the photocatalytic efficiency to be greatly improved,and the hydrogen production performance is improved by 13 times.In chapter four,the electrocatalytic activity of TiO₂ for water-splitting hydrogen production is studied.At present,the electrocatalyst with the best hydrogen evolution effect is Pt and its alloy.The disadvantage is that the Pt content is relatively high,which limits the application in industrial production.For this problem,this paper improved the condition of loading Pt on TiO₂ nanosheets for the preparation of Pt2-TiO₂.The content of Pt is 0.4 wt%by the test of ICP-MS.Using 0.5 M H₂SO₄ as the electrolyte solution,commercial Pt/C as the control sample,and the hydrogen evolution performance of Pt2-TiO₂ and commercial Pt/C are tested respectively.The electrochemical test results showed that the overpotential required for the current density reached 10 mA cm^-2 are 56 mV and 51 mV respectively,and the corresponding Tafel slopes are 33 mV dec^-1 and 31 mV dec^-1.In the potentiostatic electrolysis experiment,the current density of Pt2-TiO₂ is 92%of the initial current density after 24 hours,nearly without decline,but commercial Pt/C decreased to 43%,indicating that the Pt2-TiO₂electrocatalyst we prepared has excellent electrocatalytic activity and stability.