Shielded goethite catalyst that enables fast water dissociation in bipolar membranes

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. 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. Here we show a shielding and in-situ formation strategy of fully-interconnected earth-abundant goethite Fe +3 O(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. 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 2 SO 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.