Solid catalysts with ionic liquid layers (SCILLs) have recently attracted a lot of attention, as the ionic liquid (IL) coating can give rise to drastically improved selectivity. Here, we studied the interaction of the IL 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)-imide [C 4 C 1 Pyr]-[NTf 2 ] with Pt(111) and Pt nanoparticles (NPs) on highly oriented pyrolytic graphite under ultrahigh vacuum conditions. The IL film on Pt(111) and on the Pt NPs consists of a strongly bound monolayer and a weakly bound bulk phase. In the monolayer, [NTf 2 ] − adopts cis conformation and binds via the SO 2 groups. Adsorption of [NTf 2 ] − at Pt defect sites is preferred to adsorption at terraces, whereas preadsorbed CO blocks the adsorption at defects. Further, IL coadsorption leads to desorption and displacement of on-top CO on terraces, whereas CO resides in the bridging position. IL multilayers desorb at 380 K, whereas the strongly adsorbed monolayer on Pt resides and gradually desorbs and decomposes between 400 and 500 K. Finally, we studied the permeability of IL layers for CO by pressure modulation experiments in combination with in situ infrared reflection absorption spectroscopy. We show that the IL multilayer completely blocks CO adsorption, whereas CO easily penetrates the IL monolayer film and forms a mixed adsorbate phase. It is noteworthy that dynamic CO adsorption is much more facile on Pt NPs than on Pt(111). Our results suggest that strongly adsorbed IL monolayers may play an important role in real SCILLs.

Understanding the correlation between structure and reactivity of oxide surfaces is vital for the rational design of catalytic materials. In this work, we demonstrate the exceptional degree of structure sensitivity of the water dissociation reaction for one of the most important materials in catalysis and electrocatalysis. We studied HO on two atomically defined cobalt oxide surfaces, CoO(100) and CoO(111). Both surfaces are terminated by O and Co in different coordination. By infrared reflection absorption spectroscopy and synchrotron radiation photoelectron spectroscopy we show that HO adsorbs molecularly on CoO(100), while it dissociates and forms very strongly bound OH and partially dissociated (HO) (OH) clusters on CoO(111). We rationalize this structure dependence by the coordination number of surface Co. Our results show that specific well-ordered cobalt oxide surfaces interact very strongly with HO whereas others do not. We propose that this structure dependence plays a key role in catalysis with cobalt oxide nanomaterials.

In this work, we investigate the interaction of water with three different atomically defined cobalt oxide surfaces under ultrahigh vacuum (UHV) conditions using timeresolved and temperature-programmed infrared reflection− absorption spectroscopy (TR-IRAS, TP-IRAS) in combination with isotopic exchange experiments. The three surfaces, CoO(100), CoO(111), and Co 3 O 4 (111), are prepared in form of well-ordered films on Ir(100). Very different behavior is observed on the three surfaces, both with respect to D 2 O adsorption and desorption. On CoO(100), water adsorbs molecularly. It forms extended ice clusters even at low adsorption temperature (200 K) and which desorb molecularly at 200 K (E a,des ∼ 60 kJ•mol −1 ). A very small amount of defect sites is observed at which D 2 O dissociates and forms strongly bound OD groups. On CoO(111), the interaction with ordered facets is very weak and no adsorption occurs at these sites at 200 K. The CoO(111) films expose, however, a higher density of defects as compared to the CoO(100) films, at which D 2 O dissociates and forms strongly bound OD species with desorption temperatures of 455 ± 10 and 620 ± 10 K, respectively. In contrast to the above cases, water interacts strongly with the Co 3 O 4 ( 111) surface. At 200 K, D 2 O dissociates readily and forms a partially dissociated (D 2 O) n (OD) m network. With increasing temperature, the (D 2 O) n (OD) m network breaks up into (D 2 O) n (OD) m clusters the size of which decreases with increasing temperature. Desorption of molecular D 2 O occurs over a broad temperature range from 210 to 470 K (E a,des ∼ 60 to ∼ 140 kJ•mol −1 ). Above 470 K, only isolated OD species reside on the surface which desorb at 540 ± 20 K. Isotopic exchange experiments with D 2 O and H 2 O on Co 3 O 4 (111) show that isotopic scrambling in the (D 2 O) n (OD) m clusters is slow in comparison to exchange with the gas phase and that the clusters are composed of distinct species that show different exchange rates with the gas phase. The structure-dependent differences regarding the interaction with D 2 O are rationalized in terms of the surface termination and coordination environment of the surface ions on the three different surfaces.

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Molecular interfaces formed between metals and molecular compounds offer a great potential as building blocks for future opto-electronics and spintronics devices. Here, a combined theoretical and experimental spectro-microscopy approach is used to show that the charge transfer occurring at the interface between nickel tetraphenyl porphyrins and copper changes both spin and oxidation states of the Ni ion from [Ni(II), S = 0] to [Ni(I), S = 1/2]. The chemically active Ni(I), even in a buried multilayer system, can be functionalized with nitrogen dioxide, allowing a selective tuning of the electronic properties of the Ni center that is switched to a [Ni(II), S = 1] state. While Ni acts as a reversible spin switch, it is found that the electronic structure of the macrocycle backbone, where the frontier orbitals are mainly localized, remains unaffected. These findings pave the way for using the present porphyrin-based system as a platform for the realization of multifunctional devices where the magnetism and the optical/ transport properties can be controlled simultaneously by independent stimuli.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.202104779.