Here we report a highly active electrochemical water splitting electrode fabricated from colloidal IrOx nanoparticles and nanoporous Si stabilized by conformal TiO2. The colloidal amorphous IrOx nanoparticles are highly active for oxygen evolution reaction. However, their application for water splitting has a dilemma that the traditional annealing process could lead to low activities but the nanoparticles based electrode without annealing usually exhibited low stability. This nanostructured water splitting electrode exhibited both the high activities as the colloidal IrOx nanoparticles and comparable stability as a traditional thermal annealing fabricated electrode. The impedance study revealed that conformal TiO2 significantly inhibits the interface oxidation and maintains the high activity of colloidal IrOx nanoparticles catalysts. The conformal TiO2 interface engineering combined with nanocatalysts would be a promising strategy to achieve balanced activities and stability for water splitting.
The addition of an oxygen evolution electrocatalyst to an anode catalyst layer is demonstrated as a practical approach to address the voltage reversal of proton exchange membrane fuel cells (PEMFCs). In this work, IrOX nanoparticles uniformly deposited on niobium-doped TiO2 (IrOX/Nb0.1Ti0.9O2) by a sol–gel method are employed as reversal tolerant anodes (RTAs) for PEMFCs. The membrane electrode assembly (MEA) with this RTA possesses a reversal tolerance time of 29.1 min, which is the best result among all the as-prepared MEAs. Meanwhile, the decrease in the cell voltage of this MEA after reversal testing is only 61 mV at a current density of 1.2 A cm–2 with a degradation rate of 11.1%. The improved reversal tolerance is attributed, in part, to the uniformly distributed IrOX nanoparticles, boosting the oxygen evolution reaction and, in part, to avoid the carbon oxidation reaction by the application of a noncarbon support. This result can lay a fundamental basis for the application of RTA based on a noncarbon support to improve the anode reversal tolerance for PEMFCs.
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