Jump to main content
Jump to site search


A Comparison of the Chemical, Optical and Electrocatalytic Properties of Water-Oxidation Catalysts for Use in Integrated Solar-Fuels Generators

Abstract

The in situ optical properties and electrocatalytic performance of representative electrocatalysts for the oxygen-evolution reaction (OER) have been considered together, to evaluate systems-level effects that accompany integration of OER catalysts into a solar-fuels device driven by a tandem-junction light absorber with a photoanode top cell, i.e., a design that requires incident light to be transmitted through the OER catalyst before reaching a semiconducting light absorber. The relationship between the overpotential and optical transmission of catalyst determined the attainable efficiencies for integrated solar-fuels devices as well as the optimal band gaps for the photoanode in such devices. The systems investigated generally showed: 1) OER catalysts dissolved in acid, and were less stable in buffered near-neutral electrolytes than in strongly alkaline electrolytes; 2) Higher overpotentials were required to drive the OER at a specified current density when catalysts were operated in contact with near-neutral pH electrolytes than strong alkaline electrolytes; 3) For some of the OER catalysts, the electrocatalytic activity and in situ absorption spectra depended strongly on the preparation method; 4) Increasing the loading of electrocatalyst reduced the overpotentials and the optical transmission; 5) For the catalysts studied, the optical transmission and overpotential were generally correlated, and the trend lines did not cross, indicating that based on these factors alone, the optimal approach is to use lower loadings of highly active catalysts, rather than to use a less active but more transparent catalyst material; and, 6) For a solar-fuels device driven by semiconductors operating at the Shockley-Queisser limit and using a continuous film of a given OER catalyst in the path of incident light, the efficiency decrease due to the reduced optical transmittance that accompanies increased OER catalyst loading can be substantially greater than any efficiency increase that might be gained through the reduction in catalytic overpotential through increasing the catalyst loading; and, (7) HER catalysts possess the same performance trade-off when the light is incident through the HER catalysts as is observed for OER catalysts when the light is incident from the OER side.

Back to tab navigation
Please wait while Download options loads

Supplementary files

Publication details

The article was received on 07 Dec 2016, accepted on 09 Mar 2017, published on 09 Mar 2017 and first published online on 09 Mar 2017


Article type: Paper
DOI: 10.1039/C6EE03563A
Citation: Energy Environ. Sci., 2017, Accepted Manuscript
  •   Request permissions

    A Comparison of the Chemical, Optical and Electrocatalytic Properties of Water-Oxidation Catalysts for Use in Integrated Solar-Fuels Generators

    K. Sun, I. A. Moreno-Hernandez, W. C. Schmidt, X. Zhou, J. C. Crompton, R. Liu, F. H. Saadi, Y. Chen, K. M. Papadantonakis and N. Lewis, Energy Environ. Sci., 2017, Accepted Manuscript , DOI: 10.1039/C6EE03563A

Search articles by author