Preparation Of Photoanode Materials Based On Bismuth Vanadate And Research On Their Photoelectric Hydrogen Production Performance

The environmental problems caused by the massive combustion of fossil fuels cannot be ignored,and the preparation technology of clean energy hydrogen is constantly developing.Photoelectrochemical(PEC)water splitting produce hydrogen is one of the most promising hydrogen production strategies.In the whole water splitting system,the design of photoelectrode is the key link to optimize the conversion of light energy to hydrogen energy.Among many metal oxide semiconductors,monoclinic BiVO₄ has attracted extensive attention for photoelectrochemical(PEC)water oxidation in recent years because of its good photochemical stability,non-toxicity,appropriate band gap and strong absorption in the visible light range.However,in the actual study,the photoelectric efficiency of BiVO₄ is far lower than the theoretical limit efficiency.The strong tendency of photoelectron-hole composite in the material,low carrier transport efficiency,slow interfacial oxidation kinetics and other problems limit the split efficiency of BiVO₄ to water.Therefore,this paper will aim at these problems and improve the PEC performance of BiVO₄ from different angles.In order to provide theoretical basis and experimental basis for the design,preparation and application of efficient and stable photocatalytic materials,the mechanism of photocatalytic hydrogen production with BiVO₄ material and the corresponding regulation law were discussed.Herein,in the first study we successfully prepare defective BiVO₄/FeOOH(Vo-BiVO₄/FeOOH)photoanode by adding Bi₂S₃ QDs to introduce oxygen vacancy.The phase,composition and morphology of Vo-BiVO₄/FeOOH has been systematically studied.This Vo-BiVO₄/FeOOH photoanode demonstrates an excellent photoelectrochemical(PEC)performance for water oxidation,which has 4.71 mA cm^-2 photocurrent density at 1.23 V versus RHE under AM 1.5 G illumination.Experimental and theoretical calculation measurements confirmed that such excellent PEC performance is due to the existence of oxygen vacances and FeOOH cocatalyst,which significantly improves the charge separation.Furthermore,FeOOH cocatlayst can significantly enhance the stability for Vo-BiVO₄/FeOOH without decrease after11 h,demonstrated the ability to operate efficiently over a long period of time.In the second work,a simple modification method is developed to prepare high-performance photoanodes by depositing Ni FeOx nanolayers on BiVO₄(B/BiVO₄)after potassium borate solution treatment.The obtained Ni FeOx/B/BiVO₄photoanode has a photocurrent density of 5.25 mA cm^-2 at 1.23 V versus RHE under the illumination of AM 1.5 G,which is more than three times that of pure BiVO₄(1.6mA cm^-2)and also better than that of B/BiVO₄(3.35 mA cm^-2).It has been confirmed that these PEC performance enhancements are attributed to inhibiting surface charge recombination of BiVO₄ and accelerating the transfer of B/BiVO₄ holes to NiFeOx catalytic sites.In addition,NiFeOx/B/BiVO₄ photoanodes obtained sustainable photostability in the potassium borate electrolyte without adding other substances.This study provides a feasible way for the manufacture of low-cost and high-performance solar water decomposition catalysts.