Redox‐Functionalized Semiconductor Interfaces for Photoelectrochemical Separations
Ki‐Hyun Cho, Raylin Chen, Johannes Elbert, Xiao Su
Abstract
Abstract Redox‐mediated electrosorption is a promising platform for selective electrochemical (EC) separations, due to its molecular selectivity, high uptake, and tunability for target ions. However, the electrical energy required is mainly generated by non‐renewable energy sources, which limits its sustainability and overall impact to decarbonization. Here, a redox‐mediated photoelectrochemical (PEC) separation process using polyvinyl ferrocene functionalized TiO 2 nanorod electrodes is proposed, which integrates direct solar energy as a driver for the selective electrosorption. The photoelectrochemically‐driven oxidation and reduction with both homogeneous and heterogeneous ferrocene‐systems is investigated to establish the underlying mechanism. The PEC system can separate heavy metal oxyanions at lower voltages or even without electrical energy. At 0.3 V versus SCE, a 124 mg g −1 uptake for Mo is achieved, which is comparable to the performance of EC cells at 0.75 V versus SCE. Thus, PEC systems not only can generate energy for spontaneous redox‐separations, but also can reduce electrical energy consumption by 51.4% compared to EC cells for separation processes when coupled with an external electrical energy.