Hydrogen production from renewable resources and its reconversion into electricity are two important pillars toward a more sustainable energy use. The efficiency and viability of these technologies heavily rely on active and stable electrocatalysts. Basic research to develop superior electrocatalysts is commonly performed in conventional electrochemical setups such as a rotating disk electrode (RDE) configuration or H-type electrochemical cells. These experiments are easy to set up; however, there is a large gap to real electrochemical conversion devices such as fuel cells or electrolyzers. To close this gap, gas diffusion electrode (GDE) setups were recently presented as a straightforward technique for testing fuel cell catalysts under more realistic conditions. Here, we demonstrate for the first time a GDE setup for measuring the oxygen evolution reaction (OER) of catalysts for proton exchange membrane water electrolyzers (PEMWEs). Using a commercially available benchmark IrO 2 catalyst deposited on a carbon gas diffusion layer (GDL), it is shown that key parameters such as the OER mass activity, the activation energy, and even reasonable estimates of the exchange current density can be extracted in a realistic range of catalyst loadings for PEMWEs. It is furthermore shown that the carbon-based GDL is not only suitable for activity determination but also short-term stability testing. Alternatively, the GDL can be replaced by Ti-based porous transport layers (PTLs) typically used in commercial PEMWEs. Here a simple preparation is shown involving the hot-pressing of a Nafion membrane onto a drop-cast glycerol-based ink on a Ti-PTL.

Photonic curing, an exposure of matter to intense and short (µs) light pulses, is herein demonstrated as an effective and versatile method to activate and stabilize electrocatalysts for the electrochemical reduction of CO 2. Catalyst preparation by colloidal synthesis often makes use of surfactants (capping agents) that control the size and morphology of target nano-objects during and after their synthesis. However, this approach can severely compromise the catalytic properties of the as-synthesized nanomaterials. Photonic curing is suitable to gently remove surfactants from the catalyst surface without severely altering its overall structural properties (e.g., surface faceting), thereby increasing the abundance of those surface active sites that can participate in the desired (electro)catalytic reaction. This catalyst activation is exemplarily demonstrated on the basis of Cu nanowire (Cu-NW) catalysts synthesized by an oleylamine route and transferred to a glassy carbon (GC) support electrode. Whereas the 3D-networks of the assynthesized Cu-NW catalysts predominantly produce hydrogen as product of the electrolysis reaction photonically cured Cu-NWs, denoted hereinafter as Cu metal membrane catalysts (MMCs), show a high selectivity towards ethylene formation reaching a Faradaic efficiency of FE C2H4 = 42.4% (J C2H4 =-7.8 mA cm-2 , E =-1.1V vs RHE). This high ethylene yield can even be maintained during prolonged electrolysis of 110 h. A further beneficial effect of the photonic curing treatment is related to the substantially increased mechanical stabilization of the Cu-NW film on the support electrode induced by a 'mild' sintering of Cu-NWs which remains locally confined to their points of contact. A loss of catalyst material

State-of-the-art industrial electrocatalysts for the oxygen evolution reaction (OER) under acidic conditions are Irbased. Considering the scarce supply of Ir, it is imperative to use the precious metal as efficiently as possible. In this work, we immobilized ultrasmall Ir and Ir 0.4 Ru 0.6 nanoparticles on two different supports to maximize their dispersion. One high-surfacearea carbon support serves as a reference but has limited technological relevance due to its lack of stability. The other support, antimony-doped tin oxide (ATO), has been proposed in the literature as a possible better support for OER catalysts. Temperature-dependent measurements performed in a recently developed gas diffusion electrode (GDE) setup reveal that surprisingly the catalysts immobilized on commercial ATO performed worse than their carbon-immobilized counterparts. The measurements suggest that the ATO support deteriorates particularly fast at elevated temperatures.

State-of-the-art industrial electrocatalysts for the oxygen evolution reaction (OER) under acidic conditions are Ir-based. Considering the scarce supply of Ir, it is imperative to use the precious metal as efficiently as possible. In this work, we immobilized ultrasmall Ir and Ir0.4Ru0.6 nanoparticles on two different supports to maximize their dispersion. One high surface area carbon support serves as reference but has limited technological relevance due to its lack of stability. The other support, antimony-doped tin oxide (ATO), has been proposed in the literature as a possible better support for OER catalysts. Temperature-dependent measurements performed in a newly developed gas diffusion electrode (GDE) setup reveal that surprisingly the catalysts immobilized on commercial ATO performed worse than their carbon-immobilized counterparts. The measurements suggest that the ATO support deteriorates particularly fast at elevated temperatures.

State-of-the-art industrial electrocatalysts for the oxygen evolution reaction (OER) under acidic conditions are Ir-based. Considering the scarce supply of Ir, it is imperative to use the precious metal as efficiently as possible. In this work, we immobilized ultrasmall Ir and Ir0.4Ru0.6 nanoparticles on two different supports to maximize their dispersion. One high surface area carbon support serves as reference but has limited technological relevance due to its lack of stability. The other support, antimony-doped tin oxide (ATO), has been proposed in the literature as a possible better support for OER catalysts. Temperature-dependent measurements performed in a newly developed gas diffusion electrode (GDE) setup reveal that surprisingly the catalysts immobilized on commercial ATO performed worse than their carbon-immobilized counterparts. The measurements suggest that the ATO support deteriorates particularly fast at elevated temperatures.