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Abstract 2D architectures and superior physiochemical properties of MXene offer an exciting opportunity to develop a new class of polymer electrolyte membranes by controlling the stacking behavior of MXene nanosheets. However, assembling MXene nanosheets into macroscopic stable and high‐performance proton conductors is challenging. Here, a general strategy is reported for achieving stable and high‐performance MXene‐based heterogeneous proton conductors via crosslinked cellulose nanofiber/sodium alginate (CNF/SA). Through the coordination of calcium ions with 1D CNF/SA, MXene nanosheets with abundant hydrogen‐bonding networks are firmly locked into the heterogeneous polymer network, and meanwhile, the heterogeneous polymer chains are transformed from a randomly arranged state to a long‐range ordered arrangement, and such arranged polymer molecular channels collaborate with the tightly‐stacked MXene nanosheets jointly guide the stable and efficient proton conduction. Thus, the as‐built CNF/SA/MXene (CSM) composite membrane exhibits superior mechanical properties (164.7 MPa), proton conductivity (45.4 mS cm −1 ), power density (49.5 mW cm −2 ), and low open circuit voltage (OCV) decay rate (0.4 mV h −1 ). The design principle of 2D material anchoring through ionic‐cross‐linking and mixed‐dimensional assembly can inspire the synthesis of various ion exchange membranes for ion filtration, ion transport, ion sieving, and more.
Zhu et al. (Wed,) studied this question.