Surface And Interface Engineering Of Semiconductors Toward Highly Efficient Photocatalysis

Nowadays,energy and environmental issues are becoming more and more serious,which restricts the development of the economy.Semiconductor-based photocatalysis technologies can be used to solve these problems and realize the conversion and storage requirements from clean solar energy to chemical energy.Through photocatalysis processes,we can split water to H2 and O2,reduce CO2 into carbon-based fuels,and remove environmental pollutants.This can not only solve energy problems,but also effectively solve environmental problems.Among them,solar energy conversion and utilization through photo（electro）catalytic water splitting into hydrogen and oxygen is one of the most favorable options for converting solar energy into useable energy.The overall photo（electro）catalytic water splitting includes two half reactions,water reduction and oxidation.According to the basic principle of photocatalysis,how to broaden the light absorption edge of photocatalyst,how to improve the photogenerated charge separation and transfer efficiency,and how to reduce the overpotential of surface reaction are three important scientific problems in the field of photocatalytic research.According to these factors,the surface and interface engineering of photocatalytic materials is an effective strategy to improve their performances.Based on the surface and interface engineering of the photocatalyst,this paper studies on the photo（electro）catalytic oxygen evolution and hydrogen evolution from water splitting.1.We firstly develop a facile electrodeposition synthesis method to fabricate Ni Felayered double hydroxide（LDH）modified α-Fe₂O₃ photoanodes with enhanced photoelectrocatalytic（PEC）oxygen evolution reaction（OER）performance.The α-Fe₂O₃/Ni_0.5Fe_0.5-LDH electrode shows 3-fold higher photocurrent densities at 1.23 V vs.reversible hydrogen electrode（RHE）than bare α-Fe₂O₃,and excellent long-term durability.Mott-Schottky and Electrochemical impedance spectroscopy measurements reveal that the greatly enhanced PEC performances of α-Fe₂O₃/Ni Fe-LDH come from the reduced charge transfer resistance and improved carrier density.2.We report a simple electrodeposition method for making the {010} and {110} facets-dominated BiVO₄/Fe-based(Ni_1-xFe_x and Co_1-xFe_x)LDH interface heterostructure for boosting the PEC water oxidation performance.The as-obtained BiVO₄/Ni_0.5Fe_0.5-LDH displays 4 times higher photocurrent at 1.23 V vs.RHE,cathodic onset potential shift of 320 m V,and incident photon-to-current efficiency of around 4-fold improvement for PEC water oxidation than the bare BiVO₄.The similar results were also observed from the BiVO₄/Co0.5Fe0.5-LDH photoelectrode.Theoretical calculations were carried out to gain further insights into the nature of OER process by elucidating the electronic structure and surface reaction.The theoretical calculations reveal that the greatly improved photoelectrocatalytic performance of BiVO₄/LDH are attributed to the facts that（i）Fe-based LDHs with narrow bandgap can enhance light absorption;（ii）the metallic characteristic of BiVO₄/LDH phase-interface can facilitate the charge separation,and（iii）the LDHs as an effective OEC can increase the OER kinetics at the photoelectrode/electrolyte interface.3.We report a vaporization-deposition strategy for making the anatase TiO₂ [TiO₂（A）] nanofibers/red phosphorus（RP）core/shell heterostructure for boosting the photocatalytic hydrogen evolution from pure water and Cr（VI）reduction performance.The as-obtained TiO₂（A）/RP（30）displays the maximum evolution rate of 178 μmol?g-1?h-1,increased by about 7 times higher hydrogen evolution rate,higher Cr（VI）reduction activity,and around 4-fold improvement for photocurrent density than the bare TiO₂（A）.The greatly improved photocatalytic reduction performances of TiO₂（A）/RP are attributed to the facts that the introduction of RP nanolayer acts as sensitization layer can enhance light harvesting and the formation of interface between TiO₂（A）and RP can inhibit the recombination of photoinduced carriers in photocatalyst,leading to a high rate of photocatalytic hydrogen evolution from pure water and enhanced photocatalytic Cr（VI）reduction performance.In conclusion,we have taken the surface and interface engineering of α-Fe₂O₃,BiVO₄ and TiO₂（A）nanofibers to improve their photo（electro）catalytic water splitting performances.So the surface and interface engineering of photocatalyst is an effective strategy to improve their photocatalytic performances.