First ever video of nanoscale direct visualization of hydrogen and oxygen atoms forming water using Palladium as catalyst

Good news! Amazing stuff! This could be a game changer!

"... A rare element called palladium is known to be a good catalyst for converting gaseous hydrogen and oxygen into water, but exactly how it works remains poorly understood. So for the new study, researchers ... used a recently developed technique to watch in precise, molecular detail what was happening.

They placed samples of palladium into honeycomb-shaped nanoreactors, encased in an ultra-thin membrane of glass. Then, the gases were introduced. The whole show was viewed using high-vacuum transmission electron microscopes. ...

With further experiments, the team found the optimal method for using palladium to produce water. Adding hydrogen first, followed by oxygen, led to the fastest reaction rate. The hydrogen atoms would squeeze into the metal, then come back out when oxygen was added to produce water on the palladium’s surface. ..."

From the significance and abstract:

"Significance

Unraveling the reaction kinetics of Pd-catalyzed, water-forming hydrogen oxidation under various gas conditions has posed a considerable experimental challenge. In this study, we achieve nanoscale direct visualization of water formation from this reaction using gas cell transmission electron microscopy. We disentangle the intricate interplay between adsorption, atomic diffusion, and concurrent phase transformation of catalyst. The observed differences in water generation rates with varying gas supply sequences, corroborated by electron diffraction analysis, indicate that the rate of Pd-catalyzed hydrogen oxidation is limited by precursors adsorption. This understanding enables identifying the optimal catalytic reaction condition, holding substantial implications for applications in water generation. Furthermore, our findings advocate exploration of analogous mechanisms in other metal-catalyzed reactions.

Abstract

Palladium (Pd) catalysts have been extensively studied for the direct synthesis of H2O through the hydrogen oxidation reaction at ambient conditions. This heterogeneous catalytic reaction not only holds considerable practical significance but also serves as a classical model for investigating fundamental mechanisms, including adsorption and reactions between adsorbates. Nonetheless, the governing mechanisms and kinetics of its intermediate reaction stages under varying gas conditions remain elusive. This is attributed to the intricate interplay between adsorption, atomic diffusion, and concurrent phase transformation of catalyst. Herein, the Pd-catalyzed, water-forming hydrogen oxidation is studied in situ, to investigate intermediate reaction stages via gas cell transmission electron microscopy. The dynamic behaviors of water generation, associated with reversible palladium hydride formation, are captured in real time with a nanoscale spatial resolution. Our findings suggest that the hydrogen oxidation rate catalyzed by Pd is significantly affected by the sequence in which gases are introduced. Through direct evidence of electron diffraction and density functional theory calculation, we demonstrate that the hydrogen oxidation rate is limited by precursors’ adsorption. These nanoscale insights help identify the optimal reaction conditions for Pd-catalyzed hydrogen oxidation, which has substantial implications for water production technologies. The developed understanding also advocates a broader exploration of analogous mechanisms in other metal-catalyzed reactions."

Watch: First nanoscale video of hydrogen and oxygen atoms forming water

Watch water form out of thin air "For first time, researchers witnessed formation of tiny water bubbles in real time"

Unraveling the adsorption-limited hydrogen oxidation reaction at palladium surface via in situ electron microscopy (no public access)