Surface Microbubbles Attenuate Gas-Evolution Reaction at Soft Interfaces

Gas-evolution at reactive solid-liquid interfaces underpins many clean-energy technologies, yet microbubbles that form on these interfaces often degrade performance by blocking active sites and impeding mass transport. The mechanism by which microbubble coverage modulates local interfacial reactivity remains unclear. Here, we use a soft composite film incorporating a liquid organic hydrogen carrier (LOHC) to directly probe the coupling between interfacial reaction, bubble formation, and transport phenomena. Upon contact with an alkaline solution, base-promoted cleavage of Si-H bonds in LOHC generates H₂ at the film-liquid interface. Dual-wavelength reflective interference contrast microscopy (DW-RICM) reveals nanoscale changes in the thickness of the film driven by LOHC dehydrogenation, with rates up to 25 nm min^-1 in H₂ bubble-free regions. Spatial mapping shows that surface bubbles attenuate reactivity beneath them by approximately 2-fold due to restricted access of the alkaline phase. Meanwhile, diffusion-limited bubble growth induces local convective flows that enhance transport of the alkaline phase and dissolved products. The kinetics of thickness change and bubble growth can be tuned by varying the LOHC loading, providing a chemically driven platform for quantitative investigation of gas-evolution reactions.