The Photochemical Properties Of BiVO₄ Films With Au Nanoparticles Implantation And Surface Co-Catalysts Modification

With the development of industrialization,environmental pollution and energy crisis have become two major problems restricting the sustainable development of human beings.Therefore,the key to solve the problem is to find a new way to produce clean energy.Hydrogen energy is regarded as an ideal alternative to traditional fossil fuels due to its high calorific value and pollution-free products.The use of solar energy to obtain hydrogen gas has attracted much attention in recent years.Bismuth vanadiate?Bi VO₄?is a promising semiconductor photocatalytic material with the advantages of narrow bandgap width?Eg=2.4 e V?,low cost,easy availability and abundant reserves.However,Bi VO₄material also has some unfavorable factors,such as poor electrical conductivity,short hole diffusion distance and slow surface oxygen generation kinetics,which limit its photocatalytic hydrogen production efficiency.This dissertation,by Au nanoparticles implanted in the interior of the Bi VO₄ film and load Co-Pi,Ni Fe LDH of Bi VO₄ anode catalysts were modified,reveal the physical mechanism of nano Au in regulating Bi VO₄ film light absorption and“hot electron”transfer,as well as the main mechanism of Co-Pi,Ni Fe LDH in accelerating the photoanode water oxidation kinetics,the details are as follows:1.Gold?Au?nanoparticles were successfully implanted into the Bi VO₄ film by plasma sputtering and air annealing,and the Bi VO₄ film was formed with Au particles evenly dispersed.The experiment showed that the photocurrent density generated by Au NPs/Bi VO₄ photoanode at 1.23V vs.RHE was 1.18 m A cm^-2,which was 3.1 times higher than that of Bi VO₄.The improvement of photochemical properties in Au NPs/Bi VO₄ is partly due to the local surface plasmonic resonance effect of nano Au particles,which increases the visible light absorption of Bi VO₄ to visible light.On the other hand,due to the internal implantation of Au nanoparticles,the direct“hot electron”transfer speed in Bi VO₄ films is accelerated,and the charge separation efficiency is improved.When Au NPs/Bi VO₄ photoanode surface was modified with Co-Pi,the photocurrent density of the sample increased to 1.65 m A cm^-2?1.23V vs.RHE?,indicating that the Co-Pi as a co-catalyst could accelerate the water oxidation kinetic process on Au NPs/Bi VO₄ photoanode surface.2.Mo-doped Bi VO₄films were prepared by means of electrodeposition and air annealing.The photochemical properties of Mo-Bi VO₄films were modified under the support of Ni Fe LDH co-catalyst.By comparing the photocurrent of the sample at1.23 V vs.RHE,it was found that the photocurrent of the Ni Fe LDH@Mo-Bi VO₄photoanode reached 1.72 m A cm^-2,much higher than that of the Mo-Bi VO₄film(0.57m A cm^-2).Compared with Mo-Bi VO₄,Ni Fe LDH@Mo-Bi VO₄ has a negative shift of?0.2 V.Electrochemical impedance analysis showed that the Ni Fe LDH co-catalyst modification had the dual function of inhibiting the surface state of Mo-Bi VO₄film and promoting the surface water oxidation kinetics process,and significantly improved the photochemical properties of Bi VO₄ photoanode film.