Preparation Of Fractal Plasmonic Black Gold And Its Properties Exploration

The shortage of resources has become a problem of globalization,and as the cleanest renewable energy,the comprehensive utilization of solar energy is particularly important.At present,the use of solar energy is mainly limited to the fields of solar cells and light-to-heat conversion.Although these applications have been used in daily life,they also face many problems,such as high material application requirements and a single form of light energy utilization.Localized Surface Plasmon Resonance(LSPR)refers to the collective oscillation of free electrons in the nanostructure of noble metals under light excitation.Through the excitation and attenuation of plasmons,noble metals nanostructure can strongly absorb light energy,and an amplified electromagnetic field can be formed on the surface,generating high-energy hot electrons and converting light energy into heat.This series of phenomena is currently receiving much attention from the scientific research community.Therefore,metal nanostructure with plasmonic properties can be used as an ideal platform for a variety of applications.Traditional plasmonic materials are often isolated and dispersed nanostructures.The excitation of plasmons depends on the size,shape and spacing of the nanostructures and has a certain frequency and range.Therefore,their light absorption is limited to a narrow band,which reduces the efficiency of light utilization.From a microscopic point of view,plasmonic black-material can be seen as a combination of nanostructures of different scales or shapes,which can absorb light of different frequencies.Therefore,the plasmonic black-material has a broad band light absorption capability,resulting in a black appearance.Compared with isolated and dispersed nanostructures,plasmonic black-material can significantly improve the utilization of light.In this paper,the noble metal"gold"is used as the research object.First,by controlling the plating current density and the plating time,a gold plating layer with black surface and black appearance-black gold(B-Au)was successfully prepared,and its structure and performance were systematically studied.1:First design and prepare the plasmonic B-Au with rough surface and black appearance.The preparation process of B-Au mainly includes the following steps.First,the electroplated substrate is prepared by physical vacuum evaporation method,and then the regular substrate size is cut out(1 1 cm),and hydrophilic treatment of the plating substrate to improve the adhesion of the plating layer,by controlling the plating area to control the current density,and then controlling the plating time,finally successfully prepared B-Au,First of all,the optical properties of B-Au were tested.The UV-Visible-Near-Infrared Spectrophotometer test showed that B-Au is in the wavelength range of 300-1800 nm,and its absorption of light exceeds 80%,with high absorption in a broadband it was further verified by the photothermal conversion test.Under the irradiation of Xenon lamp(100m W/cm~2),the temperature of B-Au rose from room temperature(25℃)to 36.5℃within 2 minutes.In contrast,the temperature of smooth flat gold is almost unchanged.On the basis of testing the optical properties,due to the rough surface of B-Au and the presence of a large number of sharp areas in the nanostructure,we further tested the application of B-Au in surface Raman enhanced substrates.First,B-Au has a broadband absorption,the performance makes it possible to generate surface plasmon resonance excitation in a wide wavelength range,so this greatly simplifies the choice of excitation wavelength for Raman applications,by testing two signal molecules(Rhodamine B and 4-mercaptopyridine),Confirmed that B-Au does have excellent Raman application prospects.2:Continue to study the photoelectrocatalytic performance of B-Au.From the SEM image of B-Au,it can be seen that its nanostructure is rough and the specific surface area is large.The roughness of B-Au is about 20 by electrochemical testing.In the application of electrocatalytic oxidation of methanol,compared with B-Au and plane gold,B-Au has a significant improvement in the catalysis of methanol.By adding light to generate plasmonic hot carriers,the catalytic performance of B-Au can be further improved by comparing the peaks of methanol oxidation before and after light exposure,the peak current increased by15.2%after light exposure.On this basis,combined with semiconductor cadmium sulfide,the photoelectric performance was initially explored and the semiconductor coverage was found to affect electron transport and thus performance.