“…To increase the active material concentration, inspiration can be drawn from research on redox flow batteries, where strategies such as molecular engineering, electrolyte engineering, and slurry-based flow systems are employed ( Ding et al., 2018 ; Luo et al., 2019 ). Along this line, highly-soluble quinone-based organic CO 2 carriers ( Diederichsen et al., 2022 ) and phenazine-based PCET molecules ( Jin et al., 2020 , 2022 ) were successfully realized via rational side-chain design. It is worth noting that PCET species compatible with pH swing EMCC do not have to be organic.…”