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

Tuesday, 30 May 2017: 11:20
Churchill C2 (Hilton New Orleans Riverside)
X. Zhou, R. Liu, K. Sun, Y. Chen, E. Verlage, S. A. Francis, N. S. Lewis, and C. Xiang (California Institute of Technology)
A solar-driven CO2 reduction (CO2R) device that consists of a tandem InGaP/GaAs/TiO2/Ni photoanode in 1.0 M KOH for oxygen evolution reaction (OER), a Pd/C nanoparticles dark cathode in bicarbonate electrolyte at pH=8.0 for CO2R reaction and a bipolar membrane exhibited a solar-to-fuel (STF) conversion efficiency of 10%. The Pd/C nanoparticles showed low overpotential (< 100 mV) and high faradic efficiency (> 94%) for CO2 reduction to formate at 8.5 mA cm-2. The bipolar membrane exhibited low formate crossover and high transference number for proton and hydroxide at the steady-state pH gradient. The effective coupling between two different electrolytes that optimize the performance of CO2R reaction and OER provides new cell design spaces for efficient solar-fuel generation.