%0 Journal Article
%A Alex J King
%A Justin C Bui
%A Alexis T Bell
%A Adam Z Weber
%B ACS Energy Letters
%D 2022
%G eng
%P 2694 - 2700
%R 10.1021/acsenergylett.2c01041
%T Establishing the Role of Operating Potential and Mass Transfer in Multicarbon Product Generation for Photoelectrochemical CO2
%U https://pubs.acs.org/doi/10.1021/acsenergylett.2c01041
%8 07/2022
%! ACS Energy Lett.
%X <p><span>There is increasing interest in the possibility of photoelectrochemical (PEC) reduction of CO</span><sub><span>2</span></sub><span>&nbsp;to C</span><sub><span>2+</span></sub><span>&nbsp;products; however, the criteria for maximizing PEC solar-to-C</span><sub><span>2+</span></sub><span>&nbsp;(STC</span><sub><span>2+</span></sub><span>) rates are not well understood. We report here a continuum-scale model of PEC CO</span><sub><span>2</span></sub><span>&nbsp;reduction (CO</span><sub><span>2</span></sub><span>R) on Cu in 0.1 M CsHCO</span><sub><span>3</span></sub><span>&nbsp;and use it to optimize the design and operating conditions for generating C</span><sub><span>2+</span></sub><span>&nbsp;products. We demonstrate that the potential-dependent product distribution of CO</span><sub><span>2</span></sub><span>R on Cu requires operating near the potential that maximizes C</span><sub><span>2+</span></sub><span>&nbsp;generation rates (</span><em>V</em><span>id</span><span>), unlike PEC water splitting, which desires operation at the maximum photocurrent density. Because of this requirement, the criterion for a high STC</span><sub><span>2+</span></sub><span>&nbsp;rate includes high-photocurrent semiconductors with photovoltages near&nbsp;</span><em>V</em><span>id</span><span>&nbsp;and low series resistance. The STC</span><sub><span>2+</span></sub><span>&nbsp;rate in these systems is enhanced by optimal CO</span><sub><span>2</span></sub><span>&nbsp;transport and exhibits low sensitivity to dirunal solar irradiance variations.</span></p>