| Environmental pollution and energy shortage have become two major themes restricting human development.Photocatalysis technology,with its advantages of simple operation,mild reaction conditions,and solar energy as the driving force,has shown enormous application potential in environmental governance and alleviating energy pressure.However,the low utilization rate of sunlight by traditional photocatalysts,complexity of preparation methods,and high raw material costs have limited the practical application of photocatalysis technology.Bismuth-based semiconductor materials have attracted the attention of researchers due to their excellent photocatalytic performance,low price,and abundant reserves.Therefore,this dissertation based on bismuth-based semiconductors,employs innovative preparation methods to construct various bismuth-inclusive heterojunction photocatalysts,exploring their applications in the fields of photocatalytic pollutant degradation and photocatalytic fuel cells（PFC）.Analyze and characterize the morphology,composition,and optical properties of the prepared samples,and systematically study their ability to remove pollutants.Combine theoretical calculations and the types of reactive oxygen species generated to speculate on possible degradation pathways and performance enhancement mechanisms.Construct a PFC system,analyze its current output capability and photocatalytic degradation ability,providing references for environmental remediation and photoelectric conversion.The main research contents are as follows:（1）Rare earth element-doped Na YF4 up-conversion nanoparticles（Up-conversion Nanoparticles,UCNP）were synthesized by the thermal decomposition method.Small size Bi2O3 nanoparticles were modified on the surface of UCNP through the solvothermal method,and the modification of Ag was completed by the photoreduction method to obtain Ag/UCNP/Bi2O3 composite nanomaterials.UCNP can convert near-infrared light in sunlight into ultraviolet and visible light,enabling the composite photocatalyst to be excited by the full solar spectrum;Small size Bi2O3 has a relatively high positive charge and active sites,enabling it to selectively adsorb negatively charged pollutant molecules.This property is particularly effective for tetracycline hydrochloride（TCH）,with a maximum adsorption capacity reaching up to 717.4 mg/g.A heterostructure formed between Ag and Bi2O3,significantly enhances the photonic absorption capacity and the separation efficiency of photogenerated carriers in Bi2O3.Under simulated sunlight conditions,through the synergistic action of adsorption and photodegradation,the Ag/UCNP/Bi2O3 composite photocatalyst can completely remove 10 mg·L-1 Rhodamine B solution within 15 min.（2）Bi2O3 nanoparticles smaller than 5 nm were prepared using an improved precipitation method.These nanoparticles were then induced to grow directionally into nanosheets with the help of light irradiation,leading to the formation of Ag/Bi2O3nanosheets.The resulting Ag/Bi2O3 nanosheets retained the selective adsorption characteristics of small-sized bismuth oxide,and their photocatalytic capabilities were further enhanced due to the formation of a heterostructure between Ag and Bi2O3.Under simulated sunlight conditions,through the synergistic action of adsorption and photodegradation,the Ag/Bi2O3 nanosheets could completely remove 50 mg·L-1 of TCH within 20 min.（3）Bi2O3/Ti O2 nanotubes were prepared using electrospinning and impregnation calcination methods.The surface of the nanotubes was modified with g-C3N4 to obtain a porous structure using an improved vapor deposition method.Under simulated sunlight irradiation,the g-C3N4/Bi2O3/Ti O2 porous nanotubes could remove 87.7%of TCH with a concentration of 20 mg·L-1 within 50 min,which was 3.16 times that of pure Ti O2nanotubes.The possible photocatalytic mechanism of the heterostructure was speculated by analyzing the types of reactive oxygen species and performing density functional theory calculations.In the PFC system composed of g-C3N4/Bi2O3/Ti O2 nanotubes as the photoanode materials and copper foil as the cathode,the short-circuit current density（46.2 m A/g/cm2）and the maximum power density（6.65 m W/g/cm2）were 2.7 times and4.5 times,respectively,of those in the PFC system with Ti O2 as the photoanode.（4）BiOBr/Ti O2 nanostructures were obtained by modifying BiOBr nanosheets on the surface of Ti O2 nanotubes via a solvothermal method.BiOBr/Ti O2 has excellent adsorption and photocatalytic degradation capabilities.Under simulated sunlight,BiOBr/Ti O2 nanotubes can achieve a removal rate of 92.1%for 20 mg·L-1 of ciprofloxacin within 50 min,and its photodegradation rate is 4.2 times that of pure Ti O2and 3.6 times that of pure BiOBr.When BiOBr/Ti O2 nanotubes were used as the photoanode and Ag/Bi2O3 nanosheets were used as the photocathode in a PFC system,the resulting dual-electrode PFC system showed superior current output capabilities compared to a single-electrode PFC system.The short-circuit current density and maximum power density were 580.3 m A/g/cm2 and 49.2 m W/g/cm2,respectively,which were 2.6 times and 4.1 times than that of the BiOBr/Ti O2 photoanode PFC system,and1.5 times and 2.1 times than that of the Ag/Bi2O3 photocathode PFC system. |
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