Unassisted photoelectrochemical CO2 reduction by employing III-V photoelectrode with 15% solar-to-fuel efficiency

Solar-driven carbon dioxide reduction reaction (CO2RR) provides an opportunity to produce value-added chemical feedstocks and fuels. However, achieving efficient and stable photoelectrochemical (PEC) CO2RR into selective products is challenging owing to the difficulties associated with the optical and the electrical configuration of PEC devices and electrocatalyst properties. Herein, we construct an efficient, concentrated sunlight-driven CO2RR setup consisting of InGaP/GaAs/Ge triple-junction cell as a photoanode and oxide-derived Au (Ox-Au) as a cathode to perform the unassisted PEC CO2RR. Under one-sun illumination, a maximum operating current density of 11.5 mA cm(-2) with an impressive Faradaic efficiency (FE) of similar to 98% is achieved for carbon monoxide (CO) production, leading to a solar-to-fuel conversion efficiency of similar to 15%. Under concentrated intensity of 10 sun, the photoanode records a maximum current density of similar to 124 mA cm(-2) and maintains similar to 60% of FE for CO production. The results demonstrate crucial advancements in using III-V based photoanodes for concentrated PEC CO2RR.