Reñones, Patricia; Moya, Alicia; Fresno, Fernando; Collado, Laura; Vilatela, Juan J.; de la Peña O’Shea, Víctor A.(Journal of CO2 Utilization (ELSEVIER), April 18, 2016)
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Resumen:
In this research work, the gas phase CO2 photocatalytic reduction using water as electron donor has been
performed using hierarchical assemblies of mesoporous TiO2 1-D nanofibres synthesised by a
combination of electrospinning and sol–gel methods. In order to compare the effect of the crystallisation
step on oxygen vacancies and conductivity, two different annealing conditions have been undertaken:
under a high Ar
flow (“TiO2 Fibres-A” sample) and under static Ar (“TiO2 Fibres B” sample). Moreover,
these materials have been compared with individualised TiO2 nanoparticles prepared by a sol-gel
procedure. CO and H2 are detected as major products with all photocatalysts, with lower amounts of CH4
and CH3OH. The TiO2 nanofibres exhibit better results than the sol-gel photocatalyst, behaviour that may
be ascribed to an improved nanocrystals connection, which favours a fast charge transport along the
grain boundaries, as measured by electrochemical impedance spectroscopy (EIS). The highest CO2
reduction activity is achieved with the TiO2 Fibres B catalyst, which gives rise to ca. 4 and 2.5 times higher
H2 and CO production, respectively, than the TiO2 Fibres-A one. This sample is composed of a mixture of
anatase and rutile crystalline phases (80:20), leading to a decrease in the electron-hole recombination
rate observed by photoluminescence (PL) measurements.
