Mechanistic Insights into Hydrogen Evolution by Photocatalytic Reforming of Naphthalene

authored by

Osama Al-Madanat, Yamen Alsalka, Mariano Curti, Ralf Dillert, Detlef W. Bahnemann

Abstract

Heterogeneous photocatalysis has been widely considered, among other applications, for environmental remediation and hydrogen production. While these applications have been traditionally seen as well-separated areas, recent examples have highlighted the possibility of coupling them. Here, we demonstrate the simultaneous production of H2 and naphthalene removal from aqueous solutions with (unoptimized) photonic efficiencies of 0.97 and 0.33%, respectively, over Pt-TiO2 under simulated sunlight. Photocatalytic and spin-trapping experiments in the presence of a hydroxyl radical and hole scavengers evinced that only the photogenerated holes play a significant role in the oxidation of naphthalene. Isotopic labeling analyses showed that the evolved H2 isotopologues match those of the solvent and that deuterated water (but not deuterated naphthalene) decreases the reaction rate, suggesting its involvement in the rate-determining step. Moreover, the use of Ti18O2 does not lead to the significant formation of 18O-enriched CO2, suggesting that water is the source of the oxygen atoms. Ultimately, by considering the stable and transient reaction intermediates, we propose a plausible reaction pathway. Our work illustrates that environmental remediation can be effectively coupled to solar fuel production, providing a double purpose to photocatalytic reactions, while the mechanistic insights will be of use for the further development of this strategy.

Organisation(s)

Institute of Technical Chemistry
Laboratory of Nano and Quantum Engineering

External Organisation(s)

University of Mutah
Saint Petersburg State University

Type

Article

Journal

ACS catalysis

Volume

10

Pages

7398-7412

No. of pages

15

ISSN

2155-5435

Publication date

02.07.2020

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

General Chemistry, Catalysis

Sustainable Development Goals

SDG 7 - Affordable and Clean Energy

Electronic version(s)

https://doi.org/10.1021/acscatal.0c01713 (Access: Closed)