Flowable capacitive cathode for efficiency carbon dioxide reduction in photoelectrochemical cell

Abstract

ABSTRACT Photoelectrochemical (PEC) Cell reduction carbon dioxide (CO2) is a promising avenue for converting CO2 into valuable products. In this work, a flowable electrode with a rotating impeller collector was proposed to enhance the efficiency of the carbon dioxide reduction reaction (CO2RR) in a photoelectrochemical system. Titanium carbide (Ti3C2), with its capacitive properties, serves as a catalyst and is fluidized in the cathode chamber. The frequent contact between the Ti3C2 catalysts and the rotating impeller collector extends the catalytic reaction throughout the catholyte and enhances the efficiency of CO2RR. The feasibility of the design was verified through suspension characterization, CO2 diffusion concentration measurement, capacitance characterization, and experimental factor analysis. The PEC with a flow electrode exhibits CO and CH4 production rates of 1.64 μmol g−1h −1and 9.62 μmol g−1h−1, respectively, which are 3.5 and 7.2 times higher than those of the fixed cathode. The Faradaic efficiency for CH4 reaches 92.4%. Moreover, the collision probability of the flow electrode is 17.7%, which is significantly higher than that of the conventional bubbling fluidized electrode. In addition, the capacitive properties of Ti3C2 particles favor the continuous CO2RR under open circuit conditions, which was verified by an EDS test of Na+. Finally, the operational mechanism of the PEC system is described.