Low-Loading and Highly Stable Membrane Electrode Based on an Ir@WO_xNR Ordered Array for PEM Water Electrolysis

Abstract

Developing cheap and stable membrane electrode assembly for proton exchange membrane water electrolysis (PEMWE) plays critical roles in renewable energy revolution. Iridium is the commonly efficient oxygen evolution reaction catalyst. But the reserve in earth is a shortage. Herein, an ordered array electrode in feature of the defective Ir film decorated on external WO x nanorods (WO x NRs) is designed. Electrodeposition is carried out to prepare an iridium coating (∼68 nm in thickness) to guarantee the ordered morphology. This novel electrode obtained brilliant I−V performances (2.2 A cm −2 @2.0 V) and 1030 h stability (0.5 mA cm −2 ) with a reduced loading of 0.14 mg Ir cm −2 . The uniform dispersion Ir catalyst on the WO x substrate benefits to enhance Ir mass activity and improve the poor conductivity originating from WO x . Compared with that of sprayed electrode, the threshold current density of mass transport polarization region can be expande to at least 3.0 A cm −2 for ordered structure electrode attributed to the abundant water storage bulk. This novel Ir@WO x NRs electrode occupies a huge potential to defuse the cost and durability issues confronting with the PEMWE.

Advances in Oxygen Evolution Electrocatalysts for Proton Exchange Membrane Water Electrolyzers

“…constructed Ir coating with defects on WO x nanorods by electrochemical method. [ 324 ] The prepared Ir@WO x exhibited excellent activity (2.2 A cm ‐2 @2.0 V) with a low loading of 144 µg cm −2 . Notably, thanks to highly dispersed Ir and improved electron transport and mass transfer, a long‐term stability for more than 1030 h is obtained at 500 mA cm −2 with a degradation rate of 49.7 µV h ‐1 .…”

“…In order to give readers a more intuitive feeling for relative high stability catalysts in the literature, we have listed the catalysts in the literature whose stability test is greater than 1000 h Table 2. [297,317,319,324,336]…”

Boosting the oxygen evolution stability and activity of a heterogeneous IrRu bimetallic coating on a WO3 nano-array electrode for PEM water electrolysis

“…The Ir 3.2 Ru 1.6 @WO 3 catalyst exhibits a competitive overpotential of 245 mV at 10 mA cm À2 , as shown in Fig. 3b and e, which is lower than most values reported in published works 8,27,39,40 or the value for commercial Ir (290 mV at 10 mA cm À2 ). When the Ru core loading is xed at $17 mg cm À2 , the best activity occurs at medium Ir loading of 114.9 mg cm À2 .…”

“…5,6 There is an urgent need to design and fabricate highly active and stable oxygen evolution electrodes with reduced amounts of noble metal. 7 In our previous work, 8 Ir@WO 3 with Ir loading of 9.2-144.2 mg cm À2 shows a hybrid crystal pattern of cubic Ir and monoclinic WO 3 . The electrode exhibits a morphology based on an ordered nanoarray wrapped in a defective Ir coating (average thickness: $68 nm).…”

Development of a Bifunctional Ti-Based Gas Diffusion Electrode for ORR and OER by One- and Two-Step Pt-Ir Electrodeposition

“…Combining both hydrogen technologies, the UR-PEMFC offers the possibility of cost savings due to the use of one electrochemical cell consisting of electrodes with bifunctional catalyst layers [ 10 , 22 ]. Further cost reduction is achievable by reduction in the noble metal catalyst loading on the electrodes for PEM-based hydrogen energy systems [ 23 , 24 , 25 , 26 , 27 ].…”