Jump to main content
Jump to site search

Issue 20, 2014
Previous Article Next Article

H2 production through electro-oxidation of SO2: identifying the fundamental limitations

Author affiliations

Abstract

Sulphur dioxide (SO2), a known industrial pollutant and pulmonary irritant, is emitted to the atmosphere in excess of 120 Mt per annum. Great strides have been taken to reduce SO2 emissions, but with the growth of specifically China, and to a lesser extent India, it is on the rise again. The electrolysis of aqueous solutions of dissolved SO2 holds huge environmental potential in that SO2 is converted to sulphuric acid (H2SO4) and at the same time hydrogen gas is produced. A further benefit or incentive is that a sulphur depolarised electrolyser (SDE) operates at an applied potential that is about one volt lower than that of a regular water electrolyser. In taking this technology forward the greatest improvement to be made is in developing a suitable electrocatalyst, which is also the ‘lowest hanging fruit’ in that very limited research and development has been conducted on the electrocatalyst for this process. In this work, density functional theory is employed to model the electro-oxidation of SO2 on single crystal planes of the 4d and 5d transition metals. Two reaction mechanisms are considered, a HSO3 intermediate pathway and a SO3 intermediate pathway. The binding energies of all intermediates are found to scale with the surface reactivity (measured as the adsorption of OH). Irrespective of the pathway water needs to be activated and reduction of SO2 to elemental sulphur must be avoided. This requirement alone calls for an electrode potential of at least 0.7–0.8 V for all the investigated transition metals and thus challenges the proclaimed goal to operate the SDE at 0.6 V. A high chemical barrier is further found to severely limit the oxidation reaction on reactive metals. A much higher catalytic activity can be obtained on precious metals but at the cost of running the reaction at high overpotentials.

Graphical abstract: H2 production through electro-oxidation of SO2: identifying the fundamental limitations

Back to tab navigation

Supplementary files

Publication details

The article was received on 17 Feb 2014, accepted on 01 Apr 2014 and first published on 02 Apr 2014


Article type: Paper
DOI: 10.1039/C4CP00705K
Author version
available:
Download author version (PDF)
Citation: Phys. Chem. Chem. Phys., 2014,16, 9572-9579
  •   Request permissions

    H2 production through electro-oxidation of SO2: identifying the fundamental limitations

    R. J. Kriek, J. Rossmeisl, S. Siahrostami and M. E. Björketun, Phys. Chem. Chem. Phys., 2014, 16, 9572
    DOI: 10.1039/C4CP00705K

Search articles by author

Spotlight

Advertisements