Photocatalytic reforming of aqueous formaldehyde with hydrogen generation over TiO2 nanotubes loaded with Pt or Au nanoparticles

Abstract

Highly toxic and mutagenic formaldehyde water solutions were degraded on supported Titanium dioxide (TiO2) nanotubes (NTs) produced by anodization and loaded with Gold or Platinum nanoparticles (NPs). The noble metal NPs were deposited by the sputtering technique. The effects of the amount of NPs on the photocatalytic degradation of the formaldehyde under UV and visible light irradiation were investigated. Photocatalysis of formaldehyde solutions led to mineralization of the pollutant with simultaneous production of hydrogen. The hydrogen production rate increased with the increase in the amount of Gold and Platinum NPs deposited on the TiO2 NTs compared to pure NTs and also with the increase in formaldehyde concentration. A high selectivity in hydrogen photocatalytic evolution with respect to CO2 and CO was obtained by choosing the right amount of Platinum NPs loaded on the TiO2 NTs, i.e., the sputtering time. Additionally, hydrogen was also produced using only visible light irradiation (λ ≥ 400 or 450 nm) when Gold NPs were loaded on the TiO2 NTs. This result was interpreted as the known combined effect of electron trapping on noble metal NPs and the Resonance Plasmon Surface process. The prepared photocatalysts have the potential to be used for efficient treatment of effluents from anatomy and veterinary laboratories containing formaldehyde using UV or solar light. Depending on the NPs used, Gold for example, solar light harvesting is possible.