Enhanced Photoelectrochemical Performance Of ?-Fe₂O₃ Nanorods Array With Photothermal Conversion Materials

The solar energy was collected,converted and storage into H₂ via the photoelectrochemical cell?PEC?that provide high energy and no pollution energy,which will effectively solve the world energy depletion and environmental pollution problems.The photoelectrode is an important part of the PEC,which decides the photoelectric conversion efficiency of PEC cell.The N-type metalsemiconductor material was regarded as one of the most potentialcandidate for photoelectrode of PEC due to the advantage of suitable band-gap,high chemical stability,the high theory photocurrent density,low cost and rich resources,etc.However,the defect of inapposite conduction band position,the short hole diffusion length,the poor electrical conductivity,slow oxidation reaction kinetics and fastcarrier recombination rate of the metalsemiconductor materialresulted in the PEC performance and photoelectric conversion efficiencyis far lower than the theoretical value.In order to improve the photoelectrochemical performance of the metalsemiconductor material,the modification methods of size morphology,element doping,constructing heterojunction,surface modification were often used by researchers to enhance the photoelectrochemical performancefor the metalsemiconductor material,which made the preparation process cumbersome andexpensive.In recent years,the thermal excitation effect auxiliary enhanced the PEC performance for photoelectrodehas been studied andobtained effective achievement,the modification method is mainlyheat and promote the electrical conductivity for photoelectrodeitself via external thermal energy,which is expected to replace the common modification methods and effectively solve the deficiencies of the?-Fe₂O₃photoelectrode.However,the thermal excitation effect modification method existed faults of serious heat loss and uncontrolled heating temperaturefor photoelectrode,the photo-thermal enhancement techniqueisan improvementmodification method to in situheating and promote the PEC property of photoelectrode with photo-thermal conversion material modified the photoelectrode thermal excitated by808nm,which not only possess the advantages ofthe thermal excitation effect but also remedyits shortcomings.In paper,the theme is primarily aroundenhanced photoelectrochemical performance of?-Fe₂O₃ nanorods array with different photothermal conversion materials.The carbon quantum dots?CQDs?,Co₃O₄ and Zn Fe₂O₄were choosed to decorate the?-Fe₂O₃/TiO₂nanorods array to prepare the Co-Pi/CQDs/Fe₂O₃/TiO₂,Co₃O₄/Fe₂O₃/TiO₂and Zn Fe₂O₄/Fe₂O₃/TiO₂ nanorods array via soaking,electrodeposition and spin-coating process,respectively.And then the photothermal conversion material was excitated by 808 nm laser to producethermal energy and heat the?-Fe₂O₃/TiO₂photoanode,which enhanced the PEC properties of the?-Fe₂O₃photoanode.The influence of PEC properties for?-Fe₂O₃/TiO₂ photoanodebefore and after the photothermal effect of photothermal conversion material was excitated was studied,and the photothermalenhancement mechanism for PEC performance of?-Fe₂O₃/TiO₂photoanode was analysed.In this paper,the main research contents and results are as follows:?1?Study on the PEC performance of Fe₂O₃/TiO₂ nanorods.The TiO₂ layer was added between FTO and?-Fe₂O₃nanorods,which was used to ease the stress and chargerecombination due to the lattice mismatchbetween?-Fe₂O₃ and FTO,which can conduct electron and hinder hole,and accelerated the interfacial charge transfer rate,and increases the majority carrier concentration of the photoelectrodes,which increased the photocurrent density for?-Fe₂O₃ nanorods array photoelectrodefrom 0.56 m A cm^-2to 0.91 m A cm^-2.?2?Study on the PEC performance of Fe₂O₃/TiO₂ nanorods enhanced with CQDs photothermal.The CQDs and Co-Pi were loaded in Fe₂O₃/TiO₂ nanorods to prepare the Co-Pi/CQDs/Fe₂O₃/TiO₂nanorods array.CQDs was regarded as photosensitizer andphotothermal conversion agent to enhance the photoelectric catalytic activity of Co-Pi/CQDs/Fe₂O₃/TiO₂nanorods array.After the photothermal of CQDs was motivated,the charge separation efficiency,carrier concentration and photoelectric catalytic activity of Co-Pi/CQDs/Fe₂O₃/TiO₂nanorods array were promoted,which improved the PEC performance for Co-Pi/CQDs/Fe₂O₃/TiO₂nanorods array.Hence,the Co-Pi/CQDs/Fe₂O₃/TiO₂nanorods array can produce a photocurrent density of 3.0 m A cm^-2at 1.23 V_RHE under the 808 irradiation,which increased by 78.57%than that of without the excitation of CQDs photohermal.The result confirmed that the photohermal enhancementis an effective auxiliary way to improve the PEC performance of photoelectrode,which has the very good reference to improve the PEC performance of metal oxide material.?3?Study on the PEC performance of Fe₂O₃/TiO₂ nanorods enhanced with Co₃O₄photothermal.The electrocatalytic activity of Co₃O₄ was improvedunder the irradiation of near infrared,which can alternate CQDs and effectively improve the photoelectrochemical performance of Fe₂O₃/TiO₂ nanorods array photoelectrode.The carrier concentration,electricatalytic activity and charge transfer rate and separation efficiency for Co₃O₄/Fe₂O₃/TiO₂ nanorods array is increased by the catalytic and photothermal effect of Co₃O₄,wihich improvedthe photoelectric catalysis performance of Co₃O₄/Fe₂O₃/TiO₂ nanorods array.The Co₃O₄/Fe₂O₃/TiO₂nanorods array can produce a photocurrent density of 2.15 m A cm^-2 at 1.23 V_RHE under the 808 irradiation,which increased by 82%than that of without the excitation of Co₃O₄ photohermal.The photothermal conversion material with multiple performance?thermal and catalytic properties?was choosed to enhance the PEC performance of photoelectrode is an effective means.?4?Study on the PEC performance of Fe₂O₃/TiO₂ nanorods enhanced with Zn Fe₂O₄photothermal.The photoelectric properties and electrical conductivity for Zn Fe2O4were improved under the irradiation of near infrared and its lattice was match with the Fe₂O₃,which can further enhance the photoelectrochemical performance of Fe₂O₃/TiO₂nanorods array.The n-type Zn Fe₂O₄ materials can produce photogeneratedcharge under the irradiation of the visible light,construct heterojunctionwith Fe₂O₃/TiO₂nanorodsfor charge separation,and be a kind of excellent cocatalyst.After the photothermal of Zn Fe₂O₄ was motivated,the photogenerated charge separation efficiency of Zn Fe₂O₄/Fe₂O₃/TiO₂nanorods array is significantly increased,enhanced the photoelectric catalysis performance.The photocurrent density of Zn Fe₂O₄/Fe₂O₃/TiO₂nanorods array was 1.68m A cm^-2,increasing to 3.17 m A cm^-2 after the the excitation of Zn Fe₂O₄photohermal,increased by 89%.?5?The photothermal conversion materials of CQDs,Co₃O₄ and Zn Fe₂O₄ were taken to heat the Fe₂O₃/TiO₂ nanorods array in-situ,which can greatly improve the temperature of the photoelectrode and then enhance the photoelectric catalytic activity of Fe₂O₃/TiO₂ nanorods.Using multifunctional semiconductor photothermal conversion material to substitution the utilization for superposition of multiple modification method is achieve,reduced the complexity of the photoelectrode preparation technology and cost savings.