Boosting H2O2 dismutation via the rational design of bifunctional Ru3+–Lewis base sites on halloysite nanotubes

In this study, we report the crafting of Ru-doped binary MgAl-Layered double hydroxides (Ru-LDHs) vertically standing on the surface of carboxylic acid groups-functionalized HNTs (denoted Ru-LDHs/HNTs), aiming at constructing a bifunctional catalyst with both Lewis basic sites and metal sites. The grafted MgAl-LDHs enable a full exposure of Lewis basic sites (i.e., Mg-O 2- ) as well as of highly active Ru 3+ species. Intriguingly, the strong Lewis basic sites assist the Ru 3+ centers during H 2 O 2 activation, thereby generating a strong catalytic synergy for H 2 O 2 dismutation. Consequently, the Ru-LDHs/HNTs display excellent activity for the H 2 O 2 dismutation with a maximum reaction rate of ∼0.2 μmol O 2 s -1 , much higher than the counterpart without Lewis basic sites. The catalyst retained approximately 95% of its initial O 2 yield after three consecutive reuse cycles. Notably, under the applied assay conditions, Ru-LDHs/HNTs exhibited a marked suppression of detectable hydroxyl-radical formation, demonstrating the great activity of such bifunctional catalysts as antioxidant systems. The behaviour of the functional HNTs has been finally investigated to assess their mobility when placed on a surface and in microchannels, given their potential applications as microswimmers for in vitro chemotactic models, and as microsensors for environmental or food safety monitoring.