A capture device for capturing a target gas from a gas flow is disclosed that can be continuously used without requiring consumption of target gas binding salts. To this end, the device is arranged to generate separate acidic and alkaline streams of fluid by electrolyzing water, binding the target gas to the hydroxide ions in the alkaline fluid stream or the hydronium ions in the acidic stream, and recombining the generated streams to release the bound target gas and regenerating part of the electrolyzed water for further electrolysis. Such a capture device may for instance be used in a gas purification system, e.g. an air purification system for controlling target gas levels in a confined space such as a vehicle cabin, domestic dwelling or office space, a target gas generation system or a target gas enrichment system, e.g. for creating target gas-rich air for horticultural purposes. A method for capturing target gas from a gas flow and optionally utilizing the captured target gas is also disclosed.