Based On Two-dimensional Lanthanide Semiconductor Functional Materials Preparation And Photoelectrocatalytic Properties

In recent years,direct alcohol fuel cells?DAFCs?have received more and more attention as new clean energy sources due to the high energy conversion efficiency and non-polluting characteristics.Anode catalysts are the core components of DAFCs,so anode catalysts are one of the key factors affecting the performance of DAFCs.It is found that the semiconductor material as the carrier of the noble metal catalyst can greatly improve the electrocatalytic activity and stability of the working electrode under the illumination of the external light source.Among many semiconductor materials,lanthanide two-dimensional semiconductors have received attention because they can respond to visible light,have strong corrosion resistance,and have no pollution to the environment.In this paper,the advantages of Bi-based two-dimensional semiconductor materials as photocatalysts,BiOBr,BiVO4,BiOI,etc.,are mainly studied,and platinum?Pt?/lanthanide semiconductor catalysts are prepared by loading noble metals or materials.Excellent photoelectrocatalytic ability to catalyze the oxidation of small organic molecules,and studied the reaction mechanism of the photocatalyst catalyzing the oxidation of small organic molecules.The main research contents and experimental results of this thesis are as follows:?1?The BiOBr nanosheets with larger specific surface area were prepared by simple hydrothermal method.After the deposition of Pt nanoparticles?NPs?,the as-prepared Pt-BiOBr composites show superior electrocatalytic activities toward ethanol and methanol oxidation reaction under visible light irradiation,with the mass activities of 929.8 mA mg_Pt^-1and 751.7 mA mg_Pt^-1,6.0 and 28.4-fold enhancements than those under dark condition,respectively.The great enhancement in the photoelectrocatalytic performances can be attributed to the unique 2D nanostructure,synergistic and photocatalytic effects.?2?Bismuth vanadate?BiVO₄?,as a typical visible-light-activated semiconductor,has attracted much attention on water oxidation.In this paper,we extend it to be a visible-light response support for the application of electrocatalytic ethanol oxidation reaction?EOR?.Firstly,two dimensional?2D?BiVO4 nanosheets were synthesized,and then worked as a support for the decoration of Pt nanoparticles?NPs?.Ultra-small sizes of Pt nanoparticles with an average diameter of 3.5 nm were well dispersed on the surface of as-synthesized 2D BiVO4 nanosheets.By using as-prepared Pt-BiVO4 as working electrode,2.7 times enhanced catalytic activity for EOR was achieved under visible light irradiation compared to that of dark condition.The synergistic effect of photocatalytic and electrocatalytic together with the2D structure of BiVO₄ result in the improvement of catalytic performance.?3?Nowadays,using semiconductor to improve the performance of fuel cell reaction under light irradiation receives increasing attractions.In this paper,we used long-wavelength-absorption bismuth oxyiodide?BiOI?nanosheets to couple with graphite-like carbon nitride?g-C₃N₄?nanosheets to form a 2D/2D composite.This 2D/2D heterojunction has a broad light harvesting ability in the visible light region,which provides an advantage in the unitization of solar energy.By decoration of Pt nanoparticles,the as-synthesized Pt/g-C₃N₄/BiOI electrode shows 16.9 times under visible light?>420 nm?illumination than that of conventional electrocatalytic oxidation reaction?dark condition?.Even using 600±15 nm red light irradiation,the mass activity of Pt/g-C₃N₄/BiOI for EOR reaches to 53.1 mA mg_Pt^-1.Furthermore,the stabilities of as-prepared Pt/g-C3N4/BiOI are also improved by using light illumination.These results give a paradigm to construct 2D/2D heterostructure for solar light-enhanced electrocatalyst in fuel cell by using it broad absorption property.