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

verfasst von

H. Belhadj, S. Hamid, P.K.J. Robertson, D.W. Bahnemann

Abstract

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).

Organisationseinheit(en)

Institut für Technische Chemie

Typ

Artikel

Journal

ACS catalysis

Band

7

Seiten

4753-4758

Anzahl der Seiten

6

ISSN

2155-5435

Publikationsdatum

07.07.2017

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Katalyse, Allgemeine Chemie

Ziele für nachhaltige Entwicklung

SDG 7 – Erschwingliche und saubere Energie

Elektronische Version(en)

https://doi.org/10.1021/acscatal.7b01312 (Zugang: Unbekannt)