Research
CO2 Reduction to CO with 19% Efficiency in a Solar-Driven Gas Diffusion Electrode Flow Cell
Cheng, W.-H., Richter, M., Sullivan, I., Larson, D., Xiang, C., Brunschwig, B., Atwater, H. CO2 Reduction to CO with 19% Efficiency in a Solar-Driven Gas Diffusion Electrode Flow Cell under Outdoor Solar Illumination. ACS Energy Lett., DOI: 10.1021/acsenergylett.9b02576 (2020).
Scientific Achievement
Reprinted from Cheng, W.-H., et. al, CO2 Reduction to CO with 19% Efficiency in a Solar-Driven Gas Diffusion Electrode Flow Cell under Outdoor Solar Illumination. ACS Energy Lett., DOI: 10.1021/acsenergylett.9b02576 (2020).
Light driven PV-GDE measurement (APV = AGDE = 0.31 cm2). (a) Illustration of wire connection between the triple-junction cell and GDE cell. (b) J–U characteristic of Ni anode, solar cell with Ni anode, and Ag-NP gas diffusion cathode under 1 Sun. (c) Current, GDE potential vs RHE, and cell voltage measurement over 20 h duration. (d) Corresponding CO Faradaic efficiency and solar-to-fuel efficiency over the same 20 h duration.
Efficient solar-driven CO2 reduction to CO was realized by integrating high-efficiency photovoltaics with performance-matched, reverse-assembled gas diffusion electrodes. In reverse assembled form, the catalyst faces the gas phase CO2 limiting flooding while overcoming the low CO2 electrolyte solubility, enabling stable, high Faradaic efficiency operation.
Significance and Impact
The record 19% efficiency achieved in this directly-driven PV-GDE exceeds the theoretical maximum efficiency of a separately wired PV and electrolyzer using a DC-DC converter, demonstrating the benefit of component integration.
Research Details
Reprinted from Cheng, W.-H., et. al, CO2 Reduction to CO with 19% Efficiency in a Solar-Driven Gas Diffusion Electrode Flow Cell under Outdoor Solar Illumination. ACS Energy Lett., DOI: 10.1021/acsenergylett.9b02576 (2020).
Outdoor assessments of solar-driven PV-GDE in Pasadena, CA (APV = AGDE = 0.31 cm2). The solar irradiance was monitored with a calibrated silicon photodiode. Operating current density J (= JGDE = JPV), cell voltage Ucell, GDE potential UGDE vs RHE, CO Faradaic efficiency fFE,CO, and solar-to-fuel efficiency ηSTF were recorded for a 24 h day cycle.
Similar catalytic performance in traditional and reverse-assembled GDEs.
150 h with no catalyst flooding in reverse-assembled GDE.
20 h stable 19% solar to fuel efficiency under 1 Sun illumination
PV-GDE operates near its maximum power point by matching photoelectrode design to Ag nanoparticle catalyst loading.
Contact:
bsb@caltech.edu, haa@caltech.edu