| The consumption of traditional fossil and environmental pollution is one of the most serious worldwide problems.Therefore,the development of high performance,multifunctional materials to improve the utilization of renewable energy sources,which has received extensive attention.However,clean energy sources such as solar,wind and tidal energy are intermittent and cannot provide continuous and stable power.Hence,it is necessary to develop stable and multifunctional energy storage materials such as capacitors and photocapacitor electrode materials.Based on its high physical and chemical stability,specific surface area and excellent electron-hole separation characteristics,TiO2 semiconductor nano-array lays the foundation for unique structural design and performance optimization of highly efficient and multifunctional electrode materials.In this paper,the emerging ceramic Ti3SiC2 which can obtain TiO2-based composite after oxidation was selected as the substrate material.The TiO2-based nanoporous array structure can be prepared on the Ti3SiC2 substrate by anodization owning to its unique layered structure,excellent electrical conductivity and silicon atoms can be partially substituted by other elements.The effects of anodizing conditions,elemental doping and surface modification on the microstructure and photoelectrochemical properties of the anodized product layer were investigated systematically.The major research contents and results are as follows:?1?The surface structure and composition of anodized Ti3SiC2 and its photoelectrochemical properties were investigated.The ordered nanoporous embedding nanoparticles composite by anodic oxidation of Ti3SiC2 in fluorine containing organic electrolyte were constructed.Compared to anodized Ti which resulted in TiO2nanotubes array,the anodized Ti3SiC2 led to the formation of TiO2/C/SiO2 nanopore array.The unique nanostructure and complex phase composition make anodized Ti3SiC2possessed a visible-light photocurrent density up to 7.56?A cm-2,initial reversible area capacity of 6.18 mF cm-2,which were respectively 1.32 and 6.87 times higher than those of the anodized Ti,respectively,which may broaden the bifunctional material prospects of anodized MAX phases.?2?The photoelectrochemical properties of anodized Ti3Si C2 doped with Fe,Al or Sn were investigated,and the photoresponse characteristics and electrochemical energy storage mechanism were clarified.Results showed that Fe element was successfully doped into the Ti3SiC2 when Fe content is low by hot press sintering,and then transformed into a Fe-doped TiO2-based composite with nanoporous layer structure by anodization.The Ti3SiC2 with optimized doping content of Al or Sn corresponding to a superior photocurrent of 137.24?A cm-22 or 126.76?A cm-22 which is 18 or 16 times higher than that of the anodized Ti3SiC2(7.6?A cm-2)respectively.The enhanced photoresponse mechanism is that the generated defects in Al doped TiO2?Al-TiO2?improve the visible light absorption capacity,or the suppressed recombination of hole-electron pairs by the coupling effect of SnO2/TiO2.?3?The Al and Fe co-doped TiO2,SiO2 and C is developed on a pentabasic ceramic substrate of Al and Fe doped Ti3Si C2 via anodizing.The resulting electrode demonstrates good electrochemical performance with a specific capacitance of 12.03m F cm-2at the scan rate of 100 mV s-1and sustains a stability of 93%after 1000 cycles.Moreover,it exhibits a high solar energy conversion and storage capacity up to 59?A cm-22 and 4.33 mF cm-22 under visible light irradiation indicating that it has the potential to be used as a photocapacitor.The exploited approach in this work offers an alternative strategy for designing miniaturized difunctional photoelectrode ingredients with ordered periodic nanostructure to promote solar harvesting and utilizing of the photocapacitor.?4?SrCO3 owning an urchin-like morphology with a hierarchical nanostructure was synthesized by the hydrothermal route.The growth mechanism and capacitance characteristics of the urchin-like SrCO3 were investigated,and the basic properties after coating on anodized Ti3Si C2 were explored.The results showed that the surface of urchin-like SrCO3 was evenly distributed with nanorods with a diameter of about 50 nm and a length of 1–2?m.The crystal growth mechanism of"nuclear aggregates--nanorods embellishment--urchin-like"was proposed,and the specific capacitance was enhanced more than 6 times with the optimal surface nanorods on urchin-like SrCO3.After further compounding with anodized Ti3SiC2,the nano flake SrCO3 covered the surface and inhibited its photoelectrochemical properties. |
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