In-situ grown polyaniline catalytic interfacial layer improves water dissociation in bipolar membranes

A catalytic bipolar membrane (BPM), comprising a pair of laminated anion-cation exchange membranes and catalytic interfacial layer, can efficiently dissociate water to in-situ produce acid and base in photo-electrolysis and electrodialysis processes. Many organic-inorganic catalytic interfacial layers show good water dissociation performance but encounter membrane failure during the water dissociation process due to critical layers' delamination issue. Therefore, we hereby in-situ grow polyaniline interfacial layer (hereafter denoted as PIL) to simultaneously improve membrane durability and water dissociation performance due to electrostatic bonding and abundance of secondary amines -NH- in the PIL, respectively. Consequently, the produced PIL-BPMs accelerate the water dissociation by proton transfer reaction, which lowers transmembrane overpotential (1.87 V at 1000 A m(-2)) and water dissociation reaction resistance (7.44 Omega cm(2)) compared with the blank sample (2.82 V at 1000 A m(-2) and 12.40 Omega cm(2) water dissociation reaction resistance). While being used in a bipolar membrane electrodialysis, the resultant PIL-BPM has higher current efficiency (49.2%) and lower energy consumption (OFF: 1.01 kWh mol(-1), H+: 1.05 kWh mol(-1)), compared with blank sample (current efficiency: 35.2%, energy consumption OFF: 1.50 kWh mol(-1), H+: 1.61 kWh mol(-1)). Moreover, the PIL-BPMs also show similar to 2x greater stability due to the electrostatic bonding tactic than the blank membrane.

Automated summary

By growing a polyaniline interfacial layer in-situ, the catalytic bipolar membrane (BPM) shows improved durability and water dissociation performance, reducing transmembrane overpotential and water dissociation reaction resistance. When used in electrodialysis processes, the PIL-BPM exhibits higher current efficiency, lower energy consumption, and increased stability compared to a blank sample.