TY - JOUR

T1 - Mechanisms of Simultaneous Hydrogen Production and Formaldehyde Oxidation in H2O and D2O over Platinized TiO2

AU - Belhadj, H.

AU - Hamid, S.

AU - Robertson, P.K.J.

AU - Bahnemann, D.W.

N1 - Publisher Copyright: © 2017 American Chemical Society. Copyright: Copyright 2017 Elsevier B.V., All rights reserved.

PY - 2017/7/7

Y1 - 2017/7/7

N2 - The simultaneous photocatalytic degradation of formaldehyde and hydrogen evolution on platinized TiO 2 have been investigated employing different H 2O/D 2O mixtures under oxygen-free conditions using quadrupole mass spectrometery (QMS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The main reaction products obtained from the photocatalytic oxidation of 20% formaldehyde were hydrogen and carbon dioxide. The ratio of evolved H 2 to CO 2 was to 2/1. The HD gas yield was found to be dependent on the solvent and was maximized in a H 2O/D 2O mixture (20%/80%). The study of the solvent isotope effect on the degradation of formaldehyde indicates that the mineralization rate of formaldehyde (CO 2) decreases considerably when the concentration of D 2O is increased. On the basis of the ATR-FTIR data, the formaldehyde in D 2O is gradually converted to deuterated formic acid during UV irradiation, which was confirmed by different band shifting. An additional FTIR band at 2050 cm -1 assigned to CO was detected and was found to increase during UV irradiation due to the adsorption of molecular CO on Pt/TiO 2. The results of these investigations showed that the molecular hydrogen is mainly produced by the reduction of two protons originating from water and formaldehyde. A detailed mechanism for the simultaneous hydrogen production and formaldehyde oxidation in D 2O is also presented. (Chemical Equation Presented).

AB - The simultaneous photocatalytic degradation of formaldehyde and hydrogen evolution on platinized TiO 2 have been investigated employing different H 2O/D 2O mixtures under oxygen-free conditions using quadrupole mass spectrometery (QMS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). The main reaction products obtained from the photocatalytic oxidation of 20% formaldehyde were hydrogen and carbon dioxide. The ratio of evolved H 2 to CO 2 was to 2/1. The HD gas yield was found to be dependent on the solvent and was maximized in a H 2O/D 2O mixture (20%/80%). The study of the solvent isotope effect on the degradation of formaldehyde indicates that the mineralization rate of formaldehyde (CO 2) decreases considerably when the concentration of D 2O is increased. On the basis of the ATR-FTIR data, the formaldehyde in D 2O is gradually converted to deuterated formic acid during UV irradiation, which was confirmed by different band shifting. An additional FTIR band at 2050 cm -1 assigned to CO was detected and was found to increase during UV irradiation due to the adsorption of molecular CO on Pt/TiO 2. The results of these investigations showed that the molecular hydrogen is mainly produced by the reduction of two protons originating from water and formaldehyde. A detailed mechanism for the simultaneous hydrogen production and formaldehyde oxidation in D 2O is also presented. (Chemical Equation Presented).

KW - D O

KW - Pt/TiO

KW - formaldehyde

KW - hydrogen production

KW - photocatalytic reaction

UR - http://www.scopus.com/inward/record.url?scp=85023768766&partnerID=8YFLogxK

U2 - 10.1021/acscatal.7b01312

DO - 10.1021/acscatal.7b01312

M3 - Article

VL - 7

SP - 4753

EP - 4758

JO - ACS catalysis

JF - ACS catalysis

SN - 2155-5435

IS - 7

ER -