Solar-Driven Reduction of 1 atm CO₂ to Formate at 10% Energy-Conversion Efficiency by Use of a TiO₂ -Protected III-V Tandem Photoanode in Conjunction with a Bipolar Membrane and a Pd/C Cathode Electrocatalyst

Journal Article · 25 April 2017 · ECS Transactions (Online)

DOI: https://doi.org/10.1149/07704.0031ecst · OSTI ID:1633780

Zhou, Xinghao  ^[1]; Liu, Rui ^[2]; Sun, Ke ^[2]; Chen, Yikai ^[2]; Verlage, Erik ^[2]; Francis, Sonja A. ^[2]; Lewis, Nathan S. ^[2]; Xiang, Chengxiang("CX") ^[2]

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1. California Institute of Technology (CalTech), Pasadena, CA (United States); California Institute of Technology, Pasadena, CA
2. California Institute of Technology (CalTech), Pasadena, CA (United States)

A solar-driven CO₂-reduction (CO₂R) cell, made up of a tandem GaAs/InGaP/TiO₂/Ni photoanode in 1.0 M KOH(aq) (pH=13.7) to facilitate the oxygen-evolution reaction (OER), a Pd/C nanoparticle-coated Ti mesh cathode in 2.8 M KHCO₃(aq) (pH=8.0) to perform the CO₂R reaction, and a bipolar membrane to allow for steady-state operation of the catholyte and anolyte at different bulk pH values, was built. At the operational current density of 8.5 mA cm^-2, in 2.8 M KHCO₃(aq), the cathode exhibited <100 mV overpotential and >94% Faradaic efficiency for the reduction of 1 atm of CO₂(g) to formate. The anode exhibited 320 ± 7 mV overpotential for the OER in 1.0 M KOH(aq), and the bipolar membrane exhibited ~480 mV voltage loss with minimal product crossover as well as >90% and >95% selectivity for protons and hydroxide ions, respectively. The solar-driven CO₂R cell converted sunlight to fuels at an energy-conversion efficiency of ~10%.

• Research Organization: California Institute of Technology (CalTech), Pasadena, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• Grant/Contract Number: SC0004993
• OSTI ID: 1633780
• Journal Information: ECS Transactions (Online), Journal Name: ECS Transactions (Online) Journal Issue: 4 Vol. 77; ISSN 1938-6737
• Publisher: Electrochemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English