Solar-Driven reduction of CO2 to formate at 10% efficiency
Zhou X. et al. 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 Bipolar Membrane and a Pd/C Cathode Electrocatalyst. ACS Energy Letters, DOI: 10.1021/acsenergylett.6b00317 (2016).
Researchers constructed a cell that consisted of a tandem GaAs/InGaP/TiO2/Ni photoanode in 1.0M KOH (pH=13) that carried out an oxygen evolution reaction (OER) and a Pd/C nanoparticle-coated Ti mesh cathode in 2.8M KHCO3 (pH=8.0) that performed CO2 reduction reaction. The cell included a bipolar membrane that allowed for a steady-state operation of the catholyte and anolyte at different bulk pH values. At the operational current density of 8.5 mA cm–2, the cathode exhibited <100 mV overpotential and >94% Faradaic efficiency for CO2 reduction to formate , the anode exhibited a 320 ± 7 mV overpotential for OER , and the bipolar membrane exhibited a ∼480 mV voltage loss with minimal product crossovers and >90 and >95% selectivity for proton and hydroxide ions, respectively.
Under 1.0 Sun illumination, the cell exhibited a high solar-to-fuel conversion efficiency of 10%.