(Invited) Stand-Alone Photoreduction of Carbon Dioxide on Copper Oxide Nanowires Powered By WO3/Dye Dual Absorber

Abstract

A photoelectrochemical cell, composed of WO3/dye-sensitized solar cell (WO3/DSSC) and copper oxide (CuxO, where x = 1 and 2) nanowires as a dual absorber photoanode and cathode, respectively, is demonstrated as a stand-alone device for CO2 photoreduction to CO, H2 and formate. The single-absorber cell of a WO3 photoanode and CuxO nanowire cathode couple (WO3-CuxO) required the minimum overpotential of ~0.7 V to drive CO2 photoreduction. For the unassisted or stand-alone CO2 photoreduction, a DSSC was coupled to the WO3-CuxO system to construct a dual-absorber cell (WO3/DSSC-CuxO). In the dual-absorber cell, the long-wave band (λ > ca. 500 nm) passed through the semi-transparent WO3 film was absorbed by the dye-sensitized TiO2 electrode of DSSC. The WO3/DSSC-CuxO showed a potential gain of ~0.7 V, which resulted in the CO2 photoreduction successfully without supply of any external potential. In this stand-alone system, the primary CO2 conversion product is CO with solar-to-chemical energy efficiency of ~2.5% while H2 and formate are obtained with the energy efficiencies of 0.7% and 0.25%, respectively, in 5 h.