The device architecture features nanosized oxide-electrode (h-WO3@Ti) as WE, and nanoporous carbon (NC) as CE. An extra GE (also made from NC) is used for the G-Cap device to control the capacity. The operating mechanism of CAPode is schematically represented (Figure ). Figure . Mechanism of CAPode (h-WO3@Ti│0.5 mol L -1 H2SO4│NC@Ti) performance.