Efficient and robust IrW/WO3-x@NC/CP self-standing electrode with low Ir-loading for overall water electrolysis in acidic medium

Abstract

To further enhance the long-term durability of the cost-effective Ir-based catalysts, some acid-stable oxides are used as supports for acidic OER catalysts. Herein, taking carbon paper (CP) as the substrate, we prepared a self-standing IrW/WO3-x@NC/CP electrode via a layer-by-layer modified method. Among it, N-doped porous C framework not only provides a large specific surface for the attachment of WO3-x, but also makes up for the lack of conductivity of WO3-x and accelerates the electron transport process. The interaction between Ir and W sites in the form of IrW alloy which has generated during the high-temperature calcination and the dispersed Ir in WO3-x matrix improve the intrinsic catalytic activity. And due to the Pt-like effect of W and the tuning role of the electronic structure by the IrW alloy, IrW/WO3-x@NC/CP with an Ir content of only 19.1 µg cm−2 exhibits excellent bifunctional activity in acidic media. To obtain 10 mA cm−2, IrW/WO3-x@NC/CP just needs overpotential of 22 mV (for HER) and 206 mV (for OER) respectively with a mass specific activity of 4.008 A mgIr−1 at 1.55 V. For the whole water splitting, it only requires 1.52 V and 1.70 V to reach 10 mA cm−2 and 100 mA cm−2 respectively, and can operate continuously for over 40 h.