![]() ![]() These catalysts typically improved the water dissociation rate to some extent (lowered the over-potential voltage, see Supplementary Table 6). Since the invention of CBMs in the 1950s, several junctional catalysts such as carboxylates, silanes, PEDOTs, BiOCl, FeMIL-101-NH 2, P.E.I., lysozyme, graphene oxide, MOFs, bovine serum, TiOH, ZrOH, RCOONa, metal oxides and organic–inorganic mixtures have been trialled. The catalytic junction (reaction zone) in a CBM is of supreme importance, and the water dissociation rate mainly depends on the efficiency of junctional catalysts 7. In all these processes, a CBM works as an electrochemical membrane reactor which can efficiently dissociate water and simultaneously separate the reaction products to in-situ produce acid and base. ![]() Besides, the CBMs-integrated WD can also possess great potential for numerous industrial processes to treat concentrated salt solutions 10, 11, continuous regeneration of ion-exchange resins during water deionizing process 12, conversions of lactate into lactic acid and neutralisation of fermentation broth in fermentation reactors 13, 14. Thus, the integration of CBMs in emerging sustainable technologies can provide optimised architectures to achieve their utmost performance efficiency 4, 8, 9. It also drives the ions toward the counter electrodes by passing through the C/AEL pair, where they react with their counter-ions to in-situ produce acid and base at the same rate as their consumption in AP, HER, OER and CO 2 reduction processes and retain the system catalysts at their optimal activity 4, 7. The applied reverse bias releases the produced H +/OH − ions from the catalyst surface. Wherein a CBM, which comprises a water dissociation (WD) catalyst at the junction of cation–anion exchange layers (CEL|Cat| AEL), continuously intakes water into the catalytic junction and dissociates the feedwater into H +/OH − ion pairs 6. This perceptibly insoluble dilemma of achieving long-term optimal pH conditions is solely solvable with catalytic bipolar membranes (CBMs)-integrated in-situ acid–base generations 4. Sustainable advanced processes such as artificial photosynthesis (AP), hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and CO 2 photoreduction require highly controlled single pH media for their best performance, which is practically unachievable with the conventional ex-situ acid–base supplies 1, 2, 3, 4, 5. Small water dissociation voltages at limiting current density (U LCD: 0.8 V) and 100 mA cm −2 (U 100: 1.1 V), outstanding cyclic stability at 637 mA cm −2, long-time electro-stability, and fast acid-base generations (H 2SO 4: 3.9 ± 0.19 and NaOH: 4.4 ± 0.21 M m −2 min −1 at 100 mA cm −2) infer confident potential use of the novel bipolar membranes in emerging sustainable technologies. Here we show a shielding and in-situ formation strategy of fully-interconnected earth-abundant goethite Fe +3O(OH) catalyst, which lowers the activation energy barrier from 5.15 to 1.06 eV per HO − H bond and fabricates energy-efficient, cost-effective, and durable shielded catalytic bipolar membranes. ![]() However, inefficiency and instability are severe issues in state-of-the-art membranes, which need to urgently resolve with systematic membrane designs and innovative, inexpensive junctional catalysts. Optimal pH conditions for efficient artificial photosynthesis, hydrogen/oxygen evolution reactions, and photoreduction of carbon dioxide are now successfully achievable with catalytic bipolar membranes-integrated water dissociation and in-situ acid-base generations. ![]()
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