Sol gel graphene/TiO2 nanoparticles for the photocatalytic-assisted sensing and abatement of NO2

resumo

Human exposure to volatile organic compounds and NO2 can lead to health problems, therefore strategies to mitigate against the risks are required. Abatement and sensing are approaches which could both neutralise and monitor these species thus providing a safer environment and warning occupants of harmful levels. This paper presents pure TiO2 and TiO2/graphene hybrids synthesized through a sol-gel route. Electron optical, helium ion microscopy, X-ray diffraction and spectroscopic methods have been applied to elucidate the physical and chemical behaviour. NO2 sensing properties of TiO2/graphene hybrids formed by the addition of graphene to the reaction vessel prior to initiating the sol gel reaction followed by annealing (GTiO(2)S), and an alternative manufacturing method involving the addition of graphene to TiO2 nanoparticles which had already been annealed (GTiO(2)M) were compared and evaluated. A conductometric sensor based on TiO2/graphene prepared using material GTiO(2)S showed a higher response to NO2 compared to sensors based on pure TiO2 and TiO2/graphene prepared with material GTiO(2)M. Under UV irradiation generated by a low power LED, the sensor showed a remarkably enhanced response to 1750 ppb NO2, about double the response in the dark, and a limit of detection of about 50 ppb of NO2 (Signal/Noise = 3). Photocatalytic tests to assess the degradation of NOx showed that TiO2/graphene hybrids using material GTiO(2)S were the most active amongst the whole series of TiO2-based materials. Our data highlights the unique characteristics of material GTiO(2)S TiO2/graphene and the suitability for multi-purpose applications in the field of environmental monitoring and remediation. The capability of the material for both sensing and abatement of NOx could be exploited to offer a safer environment through providing a warning of the presence of NOx whilst also reducing levels.

palavras-chave

ACTIVATED CARBON FILTER; TITANIUM-DIOXIDE; AIR-QUALITY; THIN-FILMS; INDOOR AIR; TIO2 PHOTOCATALYSIS; GAS SENSORS; LOW-COST; ANATASE; COMPOSITE

categoria

Chemistry; Engineering

autores

Giampiccolo, A; Tobaldi, DM; Leonardi, SG; Murdoch, BJ; Seabra, MP; Ansell, MP; Neri, G; Ball, RJ

Grupos

G4 - Materiais Renováveis e Economia Circular

Projectos

ECO-SEE – ECO-innovative, Safe and Energy Efficient wall panels and materials for a healthier indoor environment (ECO-SEE)

CICECO - Aveiro Institute of Materials (UID/CTM/50011/2013)

agradecimentos

This project has received funding from the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement No. 609234. The authors wish to acknowledge Cambridge Nanosystems for supplying the graphene. Andrea Giampiccolo wishes to thank the BRE for funding his research studentship. This work was developed within the scope of the project CICECO Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (FCT Ref. UID/CTM/50011/2013), financed by national funds through the FCT/MEC and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. The Zeiss Orion NanoFab HIM was purchased as part of a package funded by EPSRC's Great Eight capital funding Grant No. EP/K022679/1 and Newcastle University. The HIM is housed at the National EPSRC XPS Users' Service, an EPSRC Mid-Range Facility. All data supporting this study are provided as supplementary information accompanying this paper.