Recycling of copper-adsorbed titanate nanotubes (TNTs) for photocatalytic hydrogen production

ABSTRACT

Titanate nanotubes (TNTs) were prepared by the hydrothermal method and rinsed at different pH values (2, 5, 8, 11 and 14). The material TNT-11 reached the best copper removal (98.1 mg·g⁻¹) with a TNT dosage of 200 mg·L⁻¹, [Cu(II)] of 20 mg·L⁻¹ and pH 7. This material presented H₂Ti₃O₇ and Na₂Ti₃O₇ as crystalline phases, a surface area of 250 m²·g⁻¹, and 13 wt.% of sodium content. The adsorbed TNT-11@Cu material was reutilized in the water splitting reaction with hydrogen production of 2139 µmol_H2·g⁻¹ after 5 h. It was found that the outstanding behavior stemmed from the formation of Cu₂O.

KEYWORDS:

• Layered titanate nanotubes
• copper removal
• adsorption
• hydrogen production

Acknowledgements

This work was supported by the SEP CONACYT-2014 S-2780 and CB-2010-01-153675 projects. M. Hinojosa-Reyes thanks the postdoctoral scholarship funding by CONACYT.

Disclosure statement

The authors declare that they have no conflict of interest.

Novelty statement

In this research work, we studied the copper removal onto titanate nanotubes synthesized at different pH values. The as-adsorbed titanate nanotubes with copper were also characterized in order to evaluate its physicochemical properties and its recycling to produce hydrogen through the water-splitting reaction. We found a copper removal of 98.1 mg g^-1 in 45 min carried out by TNT-11 (where 11 indicates the synthesis pH).

After that, this TNT-11@Cu composite was recycled and evaluated in the photocatalytic reaction reaching a hydrogen production of 2.2 times regard the bare TNT-11 material. According to the literature, there are reports about the copper removal by titanate nanotubes, but there are not reports about the reuse of the titanate nanotubes with copper adsorbed in later photocatalytic reactions for hydrogen production. There are other studies about the in-situ copper removal and photocatalytic degradation of organic pollutants. In this sense, the importance of our research work is the re-utilization of adsorbed copper/titanate nanotubes for the production of renewable energies.

Supplementary material

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