Synthesis Of Sunlight Conversion Composite Materials And Chemical And Biological Effects In Crop Growth

As the ongoing energy crisis deepens and the global warming threat becomes reality,to search for greener energy alternatives and to improve the energy consumption efficiency have become an urgent task.Because solar energy is both endlessly abundant and environmentally friendly, countlesd efforts have been dedicated to look for ways to leverage this cheap energy resource.Among the many facets of the endeavor is to boost the light conversion efficiency in the photosynthetic process of agricultural crops to augment production.Plants,algae,some bacteria and protists harness solar energy via photosynthetic processes to produce sugar and other life-essential compounds.They harvest sunlight primarily through the green pigment chlorophyll antenna complexes.However,these compounds only absorb blue and red light,leading to other parts of sunlight unused.To improve the sunlight conversion efficiency of the photosynthetic process is to convert unused sunlight to blue and red light.Since different plants possess slightly different adsorption bands,it is desirable if maximal peaks of emission of the converters can be adjusted.Based on above phenomena,it suggested us to research sunlight-conversion materials and its application in agriculture.The details as follows: 1.We describe an approach to design both wavelength and intensity tunable light converters through dual-excitation and dual-emission(DE²) phosphors to enhance light conversion efficiency.It was found that there were dual-excitation and dual-emission(DE²)in a general formula of Ca_1-xM_xS doped with Cu⁺ and Eu²⁺(M=Mg²⁺,Sr²⁺,Ba²⁺,0≤x≤1.0).The gist is that the DE² phosphors make use of ultraviolet and green light to excite the phosphors,which then emit blue and red light.The emitted light is tunable in both wavelength and intensity dependent on the composition of doped ingredients.Ca_0.6Sr_0.4S∶0.5%Cu⁺,0.1%Eu²⁺ (CSSCE)is able to enhance light conversion efficiency for photosynthesis of plants.2.Nano-particles CaS:Eu was obtained by ultrasonic co-precipitation method.The SEM image indicates the nano-particles CaS:Eu are uniform,spheric and the diameter of the particles is under 50 nm,but Ca_0.4Sr_0.6S:Eu,Cu is diamond.In contrast to that of the phosphor synthesized by the high temperature solid reaction,the excitation spectrum(UV area)of the nano-particles synthesized by sintering the precursor shifts to blue.The emission spectrum is a broad band and the emission peak locates at 650 nm,which is ascribed to the transition of 4f⁷→4f⁶5d¹ of Eu²⁺.3.There were a long-red emitting(⁴F_9/2→⁴I_15/2)of Er³⁺in the SrY₂S₄ and BaY₂S₄:Er³⁺.Ba_1.997Ca_0.003(Y_0.88Er_0.12)₂S₄:Eu is considered as a novel and steady red phosphor candidate with two strong broad bands in ultraviolet and green regions,and long-red emitting.4.Nano-particles of red phosphor Ca_0.8Zn_0.2TiO₃:Pr³⁺,Na⁺ was synthesized by sintering the precursor.The analysis results indicated that the uniform,spheric nano-particles of Ca_0.8Zn_0.2TiO₃:Pr³⁺,Na⁺ can be obtained when the precursor was sintered at 1000℃for 5 h.The diameter of nano-particles is under 50 nm.The excitation spectrum of the nano-particles shifts to blue.M_xCa_2-xZn₄Ti₁₅O₃₆:Pr doped with Ba²⁺is considered as a novel and steady red phosphor candidate to convert ultraviolet to red emitting.5.The luminescent hybrid layer materials were synthesized by replacement of Eu³⁺into LDHs layers,or by intercalation of organic anions or Eu(DPA)₃^3-complex into LDHs interlayer.It was found that MgAlEu-DPA-LDH and MgAl-Eu(DPA)₃-LDH are double function materials,could selectivity absorbed infrared and have red luminescence at the same time.6.A series of core@shell hybrid materials were prepared by using silicone,stearic acid(SA),polystyrene-block-acrylic acid(PS-b-PAA)and Eu-doped PS-b-PAA(Eu-PAA-PS)as organic shell,using CaS:Eu as inorganic core,respectively,which studied the effect of coated surface of alkaline sulfide phosphor.The water resistance of coated CaS:Eu has been enhanced obviously. 7.Nano composite polyethylene film(NCPF)was prepared with CaS:Eu nano-material and PE.In contrast to the normal film,NCPF presents better scattered performance,physics performance and sunlight conversion efficiency.8.The sunlight conversion polyethylene film for agricultural greenhouse(SCPFAG),the sunlight conversion polyethylene mulch film (SCPMF)and sunlight conversion-reflected polyethylene film(SCRPF) were designed and prepared by using DE² and others as raw materials. The photosynthesis and visible growth effects of tobacco were enhanced in agricultural tests of above films.9.A method for simultaneous and rapid determination the content of fragrance in tobacco leaf by reverse-phase HPLC was developed.It was found as follows:In tobacco aging period,SCPMF and SCRPF were commonly propitious to accumulate chlorogenic acid,rutin and citric acid in above leaf,but it was baneful for malic acid and citric acid in below leaf.