Preparation And Photocatalytic Activity Of Boric Acid Functionalized TiO₂ And Ni-NiO Nanoscale Heterosurfaces

Photocatalysis technology has important research value in solving environmental pollution and the energy crisis.In recent years,it has become a research hotspot to improve the photocatalytic performance by modifying the traditional photocatalyst,developing new photocatalyst and improving the experimental conditions of photocatalysis.Based on this,two different photocatalysts are developed and applied to photocatalytic degradation of organic pollutants and photocatalytic hydrogen production.The samples show excellent catalytic performance.It is of great significance to promote the research and development of photocatalysis.The research contents are as follows:?1?In this paper,a series of boric acid functionalized TiO₂ photocatalysts?TiO₂-xB-y?are prepared by hydrothermal method using tetrabutyl titanate,absolute ethanol and boric acid as raw materials.The obtained samples are characterized by TEM,SEM,XRD,Raman,nitrogen adsorption and desorption experiments,UV-vis,XPS,and NH₃-TPD.The results show that the amount of boric acid and calcination temperature are important factors affecting the structural characteristics of TiO₂ photocatalyst.Boric acid not only promotes the hydrolysis of tetrabutyl titanate in the hydrothermal process,but also plays the role of supporting TiO₂ with solid template in the calcination process to generate catalyst with large specific surface area and pore structure.At the same time,proper amount of boric acid is conducive to the preparation of TiO₂ catalyst with high?001?/?101?crystal surface ratio.Appropriate calcination temperature is helpful for TiO₂ catalyst to have large specific surface area.?2?The photocatalytic performance of boric acid functionalized TiO₂ is studied.The results show that the prepared TiO₂ has excellent photocatalytic degradation of organic pollutants and photocatalytic hydrogen production performance.Among the TiO₂-xB-y series of photocatalysts,TiO₂-10B-600 has the best photocatalytic performance for degradation of organics,the degradation rate of phenol reaches 100%after 5 hours of light;and the degradation rates of methyl orange?MO?and methylene blue?MB?are 80%and 100%after 7hours of light,respectively.TiO₂-10B-500 has the best photocatalytic hydrogen production performance,and the hydrogen production rate is 168.4umol/h/g_cat.The appropriate calcination temperature and boric acid content can help TiO₂ samples to have more photocatalytic activity sites,thus showing more excellent photocatalytic activity.?3?Well-dispersed Ni-based nanocrystals with Ni-NiO heterosurfacesare built on cellulose-derived carbon?Ni-C-500?,which exhibits outstanding photocatalytic performance in the hydrogen evolution from water.The content of Ni and calcination temperature of catalyst are screened and the dosages of sacrificial agent in the photocatalytic system are also optimized.Under optimal conditions,the hydrogen evolution rate on Ni-C-500 in the presence of Eosin Y and triethanolamine?TEOA?reaches to 13.5 mmol/g_cat/h in first hour,which is even higher than that on commercial Pt?20wt%?/C catalyst(11.4 mmol/g_cat/h).Moreover,the total hydrogen evolution volume of Ni-C-500 is about twice that of commercial Pt?20wt%?/C in five hours of irradiation.Density Functional Theory?DFT?calculations further demonstrate that the NiO islands on Ni?111?surface facilitate the adsorption of water molecule because of the interaction between oxygen atom of NiO island and hydrogen atom of water.The dissociation of water into adsorbed hydrogen?Had?and hydroxyl?OHad?on Ni-NiO surface is also allowed in terms of energy.Furthermore,produced H_add around NiO island of Ni?111?surface is more easily to form hydrogen on Ni-NiO heterosurface than on clean Ni?111?surface.