Hydrogen spillover is the surface migration of activated hydrogen atoms from a metal catalyst particle, on which they are generated, onto the catalyst support. The phenomenon has been much studied and its occurrence on reducible supports such as titanium oxide is established, yet questions remain about whether hydrogen spillover can take place on nonreducible supports such as aluminium oxide. Here we use the enhanced precision of top-down nanofabrication to prepare controlled and precisely tunable model systems that allow us to quantify the efficiency and spatial extent of hydrogen spillover on both reducible and nonreducible supports. We place multiple pairs of iron oxide and platinum nanoparticles on titanium oxide and aluminium oxide supports, varying the distance between the pairs from zero to 45 nanometres with a precision of one nanometre. We then observe the extent of the reduction of the iron oxide particles by hydrogen atoms generated on the platinum using single-particle in situ X-ray absorption spectromicroscopy applied simultaneously to all particle pairs. The data, in conjunction with density functional theory calculations, reveal fast hydrogen spillover on titanium oxide that reduces remote iron oxide nanoparticles via coupled proton-electron transfer. In contrast, spillover on aluminium oxide is mediated by three-coordinated aluminium centres that also interact with water and that give rise to hydrogen mobility competing with hydrogen desorption; this results in hydrogen spillover about ten orders of magnitude slower than on titanium oxide and restricted to very short distances from the platinum particle. We anticipate that these observations will improve our understanding of hydrogen storage and catalytic reactions involving hydrogen, and that our approach to creating and probing model catalyst systems will provide opportunities for studying the origin of synergistic effects in supported catalysts that combine multiple functionalities.

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We describe a novel parallel method for the patterning of proteins with nanoscale resolution. Combining nanoimprint lithography (NIL) and molecular assembly patterning by lift-off (MAPL), we produced streptavidin patterns with feature sizes in the order of 100 nm. A stamp is imprinted into a heated PMMA film followed by a dry etching step that converts the topography into a PMMA/Nb 2 O 5 contrast. A biotin functionalized copolymer, poly(L-lysine)-graft-poly(ethylene glycol)-biotin (PLL-g-PEG/PEG-biotin), spontaneously adsorbs on the oxide surfaces. After PMMA lift-off, the background is backfilled with protein-resistant PLL-g-PEG. We show that streptavidin selectively adsorbs on the biotin areas and thus can be used as a universal platform for immobilization of biotin-tagged molecules. This novel process is a parallel patterning method that is fast, reproducible, and economic. The PEG-copolymer can be functionalized with a variety of bioactive groups and thus allows a great flexibility in terms of surface chemistry.