Study On Spectral Radiation Characteristics Of Nano-catalysts In Hydrogen Production By Solar Photodissociation Of Water

As an ideal secondary energy source,hydrogen energy has the advantages of high energy density,storability,transportability,and no pollution.In the future,the demand for hydrogen energy will increase significantly.Hydrogen energy become"Aristocrats Energy" due to the high cost of hydrogen production,while solar energy has the advantages of unlimited reserves,development and utilization of cleanliness,etc.,solar energy photocatalytic decomposition of water into hydrogen to provide a huge energy for human society.However,in the research of solar photocatalytic hydrogen production,the nanoparticle-containing nanofluid translucent medium's absorption of light and the internal radiation transmission mechanism are not clear,which seriously restricts the development of the photocatalytic industry.Therefore,in this paper,experimental tests and theoretical studies have been carried out to solve the problem of radiation transmission in the nanofluid translucent medium during the water splitting for hydrogen production by utilization of solar energy.In this paper,the background of hydrogen production from solar photolysis of water and the semi-transparent medium for hydrogen production are studied.The Pt/TiO2 catalyst particles are prepared,and the on-line test system for simulated hydrogen photolysis of water in indoor water is improved to achieve the same experimental conditions in all weather conditions.An off-line solar photocatalysis device based on Fresnel lens concentrating was designed and constructed.Experimental tests were conducted to investigate the effects of reaction conditions such as reaction temperature,light intensity,and particle concentration on the photocatalytic hydrogen production.The catalyst was compared with seawater and Hydrogen production under fresh water conditions.The experimental results show that there is an optimal temperature for hydrogen production from photolysis of water.According to the experiment and the thermodynamics theory,the optimal reaction temperature is 55?;the amount of hydrogen produced by the photocatalyst in seawater is 102%higher than that of freshwater;Photolysis water average hydrogen production reached 17.0 mL/h.The particles and the base fluid in the nanofluid translucent medium were taken as the research object.The Monte Carlo method was used in combination with the experimental measurement and Mie theory.The radiation transmission model of the beam in the nanofluid was established according to reality,and the particles were divided into large scales according to the particle size.Particles and small-scale particles were used to study the effects of particle size parameters and the optical constants of the base fluid on the spectral attenuation parameters,spectral absorption coefficients,asymmetry factors,scattering phase functions,and spectral transmittance of the nanofluid.The results show that the particle size parameters have a great influence on the spectral radiation characteristics and spectral transmittance of nanofluids,while the optical constants of the base fluids have little effect on this;the spectral characteristics of nanofluids containing small-scale particles will change smoothly with the parameters.However,in the case of nanofluids containing large-scale particles,the spectral characteristic parameters fluctuate owing to the influence of diffraction effects.From the experiment of ultrasonic assisted photolysis of water for hydrogen production,experimental measurements and theoretical calculations were used to study the reasons for the increase in hydrogen production from ultrasound-assisted solar photolysis of water from the perspective of photon absorption.Experiments were conducted to measure the state of particle agglomeration with different ultrasound times.The effect of particle equivalent particle size and absorbance of nanofluids was extended to the effect of small particle size on the absorption rate of nanofluids and the related optical parameters such as the scattering phase function.The evaluation standard for the effective absorbance of the spectrum was first proposed.The results show that under the ultrasonic condition of 40 kHz,it is suggested that the pre-ultrasound time for hydrogen production on TiO2-based catalysts is 18 minutes,and the optimal particle size for TiO2-based nanofluids is 80 nm.