Electrochemical carbon dioxide (CO2) capture using supercapacitive systems is a promising green technology but remains limited by low uptake rates and high energy requirement. Here, we present a membrane-integrated supercapacitor system that addresses these challenges by decoupling electrode environments with a cation exchange membrane. This configuration sustains high hydroxide concentration at the gas-facing negative electrode, generated through dynamic water dissociation within the electric double layer. The resulting localized alkaline interface enhances CO2 capture by driving its conversion into (bi)carbonate species via a pH-swing mechanism. The system achieves a CO2 uptake of up to 893 mmol/kg with a fast rate of 1281 mmol/kg/hour at -1.4 V under 20% CO2. Energy consumption as low as 32 kJ/mol is obtained at -0.8 V under 20% CO2 together with a long lifetime over 200 hours at -1.0 V, 10% CO2. These findings establish a robust platform for electrochemical CO2 capture and underscore the importance of localized chemical environments in supercapacitive swing adsorption.

This study investigates a pH-universal hydrogen oxidation reaction (HOR) catalyst based on a RuZr alloy supported on zirconium oxynitride, enabling simultaneous optimization of hydrogen and hydroxyl binding energies. The catalyst was synthesized via a urea-glass crystallization route, yielding highly dispersed RuZr alloy nanoparticles strongly coupled with the oxynitride support. RuZr@ZON exhibits high HOR activity with exchange current densities (J0) of 2.14 mA cm- 2 in alkaline, 2.56 mA cm- 2 in acidic and 2.02 mA cm- 2 in neutral media, and achieves a Ru atomic dispersion of 87.9% with an atomic utilization of 5.97%, demonstrating pronounced tolerance to CO poisoning across all pH environments. The enhanced performance originates from a cooperative Volmer-Heyrovsky mechanism facilitated by balanced HBE/OHBE and accelerated H2O desorption, as revealed by electrochemical analysis and DFT calculations. This work establishes a clear structure-activity relationship and provides an effective strategy for designing durable, atom-efficient HOR catalysts operable across a wide pH range.