Paired electrolysis by regulated electronic distribution and lowering of overpotential with enhanced current density

Abstract

This review highlights the pairing of an oxidation half-reaction with a reduction half-reaction with compatibility at a lower potential for simultaneously generating desirable products at the electrode with current–voltage characterization. The cathodic hydrogen evolution (HER) or CO₂ electroreduction (eCO₂R) is accelerated by pairing with anodic oxidation, which facilitates an electrified simultaneous reaction with maximized atomic and energy efficiencies. First, we emphasize the anodic oxidation for obtaining value-added products to highlight its significance for pairing with the cathodic process. We also highlight by comparing the materials for anodic oxidation in the paired electrolysis process. The unique features of cell design include (a) an H-type electrochemical cell and (b) flow cell electrolyzers that are evaluated before discussing their interfacial electron distribution, free-standing electrodes, and significance, focusing on effective electrodes for H₂ production. Furthermore, the role of single atoms of transition elements, nanostructures and their effects in lowering the overpotential are included. A special emphasis was given to the electrode kinetics of simultaneous electrolysis with extension to prototypes for continuous paired electrolysis with a focus on critical factors in the fabrication process, device performance, and long-term production challenges. In light of the limitations and potentials, we discuss the challenges and solutions through electronic structure modification, device modification, and cell simplification as conclusive remarks and outlook.