A framework for understanding efficient diurnal CO 2 reduction using Si and GaAs photocathodes

Yap, Kyra M. K.; Lee, Sang-Won; Steiner, Myles A.; Avilés Acosta, Jaime E.; Kang, Dongkyun; Kim, Donghwan; Warren, Emily L.; Nielander, Adam C.; Jaramillo, Thomas F.

doi:10.1016/j.checat.2023.100641

DOE OSTI · 1992016

A framework for understanding efficient diurnal CO 2 reduction using Si and GaAs photocathodes

Yap, Kyra M. K.·Lee, Sang-Won·Steiner, Myles A.·Avilés Acosta, Jaime E.·Kang, Dongkyun·Kim, Donghwan·Warren, Emily L.·Nielander, Adam C.·Jaramillo, Thomas F.

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Abstract

Integrated solar fuels and photoelectrochemical (PEC) CO 2 reduction (CO 2 R) are promising pathways toward producing value-added chemicals from CO 2 . However, improvements are needed in activity and selectivity as well as in fundamental understanding of device behavior to engender wide deployment. Here, we report two single-junction, integrated photocathodes for PEC CO 2 R based on TOPCon Si and GaAs substrates, which achieve -10 mA cm -2 at -0.33 V vs. RHE with 41% selectivity to C 2+ products and at -0.03 V vs. RHE with 27% selectivity to C 2+ products, respectively. We investigated the viability of a light-mediated strategy to direct selectivity in buried-junction PEC devices and confirmed that these devices could be optimized independently and described by the physics-based models of the individual components. Finally, we designed a framework to assess operational modes for PEC CO 2 R devices and demonstrated this framework under continuous galvanostatic control and variable illumination conditions.

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14 SOLAR ENERGY 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY CO2 reduction GaAs catalysis diurnal electrocatalysis electrochemistry light photoelectrochemistry solar solar fuels

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Yap, Kyra M. K., Lee, Sang-Won, Steiner, Myles A., Avilés Acosta, Jaime E., Kang, Dongkyun, Kim, Donghwan, Warren, Emily L., Nielander, Adam C., Jaramillo, Thomas F.. 2023-05-22. A framework for understanding efficient diurnal CO 2 reduction using Si and GaAs photocathodes. https://doi.org/10.1016/j.checat.2023.100641

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