Synthesis and characterisation of materials for photoelectrochemical applications

Photocatalysis;Catalysts--Synthesis;Photoelectrochemistry;Titanium dioxide

Randorn, Chamnan ; Irvine, John T. S. ; Irvine, John T. S.

University:University of St Andrews

Department:Chemistry (School of)

关键词: Photocatalysis;    Catalysts--Synthesis;    Photoelectrochemistry;    Titanium dioxide;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/1716/ChamnanRandornPhDThesis.pdf?sequence=3&isAllowed=y

来源: DR-NTU

【 摘 要 】

The preparation of visible light driven photocatalysts for photocatalytic water splittinghas been achieved by a CO₂ free, low cost and simple novel method. Combination ofperoxide based route with organic free solvent and titanium nitride, carbon freeprecursor and air and moisture stable, would be useful. Clear red-brown solution oftitanium peroxo species was obtained by dissolution of TiN in H₂O₂ and HNO₃ acid atroom temperature without stirring. The resultant red brown solution is then used as atitanium solution precursor for yellow amorphous and yellow crystalline TiO₂synthesis. Visible light photoactivity of the samples was evaluated by photooxidationof methylene blue and photoreduction producing hydrogen from water splitting.The high surface area of yellow amorphous TiO₂ exhibits an interesting property ofbeing both surface adsorbent and photoactive under visible light forphotodecolourisation of aqueous solution of methylene blue. However, it might notappropriate for hydrogen production.Nanoparticulate yellow crystalline TiO₂ with defect disorder of Ti³⁺ and oxygenvacancies depending upon synthesis conditions has been characterised by ESR, XPS,CHN analysis and SQUID. Single phase rutile can be produced at low temperature. Itis stable at high temperature and the red shift of absorption edge increases with thetreatment temperature. Yellow crystalline TiO₂ exhibits an interesting property ofbeing photoactive under visible light. The best photocatalytic performance wasobserved for 600°C calcination, probably reflecting a compromise between red shift and surface area with changing temperature. Moreover, overall water splitting into hydrogen and oxygen might be obtained by using this material even in air atmosphere.Photoactivity can be improved by testing under anaerobic atmosphere and/or addingsacrificial agent. Quantum efficiency under visible light is still low but comparable toother reports. The maximum efficiency varies from 0.03 % to 0.37 % for hydrogenproduction and from 0.03 % to 0.12 % for oxygen production, depending on photonenergy and sacrificial agents.