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A self-assembled monolayer (SAM) of L-cysteine [HSCH 2 CH(NH 2 )COOH] was prepared on a Au(111) surface by vapor deposition in ultrahigh vacuum and was characterized by techniques of temperature-programmed desorption (TPD), Cs + reactive ion scattering (Cs + RIS), and low-energy secondary ion mass spectrometry (LESIMS). Analysis of the amino acid functional groups of SAM indicated that L-cysteine molecules exist in the zwitterionic form. Upon physisorption of the D 2 O overlayer on the SAM, the -NH 3 + functional group of cysteine readily exchanges their H atoms with D 2 O in the temperature range 125-230 K. The H/D exchange of the -NH 3 + group sequentially occurs with D 2 O molecules that are directly hydrogen-bonded to the SAM, and the long-range proton transfer to the upper layer water molecules does not occur. Temperature-programmed reaction study and kinetic analysis yielded an activation energy of 13 ( 1 kJ mol -1 for the H/D exchange reaction, which suggests proton tunneling as a mechanism.

Compared to traditional deposition techniques, in situ growth of nanoparticles on material surfaces is one of the more time- and cost-effective ways to design new catalysts. The B-site transition-metal cations in perovskite lattice could be partially exsolved as nanoparticles under reducing conditions, greatly enhancing catalytic activity. Here, we demonstrate that growing nanoparticles on the surface of a layered perovskite La0.8Sr1.2Fe0.9Co0.1O4±δ (LSFC), which could be applied as a redox stable and active electrode for intermediate-temperature symmetrical solid oxide fuel cells (IT-SSOFCs). Substitution of a proper amount of Co into the layered perovskite can thus optimize cathode and anode performance simultaneously. For example, the polarization resistances (R p) of LSFC electrode at 800 °C are 0.29 and 1.14 Ω cm2 in air and in 5% H2/N2 respectively, which are much smaller compared with the R p of Co-free La0.8Sr1.2FeO4±δ. The lower polarization resistance for LSFC in air can be mainly attributed to the enhanced electrical conductivity through the partial substitution of iron by cobalt in La0.8Sr1.2FeO4±δ. Meanwhile, the electrocatalytic activity of H2 greatly improved, because of the formation of exsolved homogeneous Co0 nanoparticles on the surface of LSFC, which appears to promote hydrogen oxidation reaction. Lower polarization resistance of 0.21 Ω cm2 in air and 0.93 Ω cm2 in 5% H2/N2 at 800 °C could be obtained further by examining an LSFC–Gd0.1Ce0.9O2−δ (CGO) composite as an electrode for IT-SSOFCs.

In situ reduction of LSMF perovskite promoted Ruddlesden–Popper RPLSMF formation with Fe nanoparticles, exhibiting outstanding electrochemical performance as a SOFC electrode.

Distribution of electrolyte ions near the surface of water or ice is a subject of interest in both fundamental chemistry and atmospheric chemistry of sea-salt aerosols and ice particles. The ion distribution at the surface of these particles may affect their reaction with ozone and organic species in the troposphere and the generation of reactive halogen species. [1,2] In early studies, the surface of aqueous solutions containing simple electrolytes such as alkali halides was thought to be deficient of ions, as inferred from the surface tension of solutions.[3] Molecular dynamics (MD) simulations have been widely employed since the 1990s to study the molecular details of solvation and segregation of atomic ions in water clusters.[4-8] MD calculations [6][7][8] predict that the large and polarizable anions are more readily available at the surface than the small nonpolarizable cations, in both water slab models [8] and clusters of finite sizes. [6,7,9] Photoelectron spectroscopic studies [10] of anionic water clusters in the gas phase support the surface residence of the larger halide anions by comparing the ionization energies with calculations. Further studies of the anionic clusters [X À (H 2 O) 1-5 , X= F, Cl, Br and I] using vibrational spectroscopy [11][12][13] indicate that the larger halides (Cl À , Br À and I À ) are solvated at the surface of water clusters. The spectra from clusters with the larger halides reveal a hydrogen-bonding network of water molecules, which supports surface solvation of anions, whereas the spectra from the F À -containing clusters lack such hydrogen-bonding features. [12b, 13] A limited number of experimental studies were performed to investigate the ion distribution at the surface of real aqueous solutions, and basically none at ice surfaces. Morgner and co-workers [14] measured He(I) photoelectron spectra from the surface of concentrated aqueous solutions of CsF and observed that the salt concentration is strongly depleted in the surface region. MD simulations from the same group [15] explain the phenomena by the circumstance that the ions near the surface mostly keep their first solvation shell intact. Using Xray photoelectron spectroscopy and scanning electron microscopy, Ghosal et al. [16] observed selective segregation of Br À ions to the surface of a NaCl crystal, which was slightly doped with Br À ions, under conditions of relative humidity, where the condensed water films caused partial dissolution of the crystal surface. Their results provide the first experimental evidence for preferential segregation of large halide anions to the surface of mixed alkali halides. More recently, vibrational sum frequency generation spectroscopy for sodium halide solutions [17] [a] J

A-site ordered PrBaMn2O(5+δ) was investigated as a potential cathode for CO2 electrolysis using a La(0.9)Sr(0.1)Ga(0.8)Mg(0.2)O3 (LSGM) electrolyte. The A-site ordered layered double perovskite, PrBaMn2O(5+δ), was found to enhance electrocatalytic activity for CO2 reduction on the cathode side since it supports mixed valent transition metal cations such as Mn, which could provide high electrical conductivity and maintain a large oxygen vacancy content, contributing to fast oxygen ion diffusion. It was found that during the oxidation of the reduced PrBaMn2O(5+δ) (O5 phase) to PrBaMn2O(6-δ) (O6 phase), a reversible oxygen switchover in the lattice takes place. In addition, here the successful CO2 electrolysis was measured in LSGM electrolyte with this novel oxide electrode. It was found that this PrBaMn2O(5+δ), layered perovskite cathode exhibits a performance with a current density of 0.85 A cm(-2) at 1.5 V and 850 °C and the electrochemical properties were also evaluated by impedance spectroscopy.

Protonic ceramic electrochemical cells (PCECs) have attracted considerable attention owing to their ability to reversibly convert chemical fuels into electricity at low temperatures below 600 °C. However, extreme sintering conditions during conventional convectionbased heating induce critical problems for PCECs such as nonstoichiometric electrolytes and microstructural coarsening of the electrodes, leading to performance deterioration. Therefore, we fabricated PCECs via a microwave-assisted sintering process (MW-PCEC). Owing to the ultrafast ramping rate (∼50 °C/min) with bipolar rotation and the resistive heating nature of microwave-assisted sintering, undesirable cation diffusion and grain growth were effectively suppressed, thus producing PCECs with stoichiometric electrolytes and nanostructured fuel electrodes. The MW-PCEC achieved electrochemical performance in both in fuel cell (0.85 W cm −2 ) and in electrolysis cell (1.88 A cm −2 ) modes at 600 °C (70% and 254% higher than the conventionally sintered PCEC, respectively) demonstrating the effectiveness of using an ultrafast sintering technique to fabricate high-performance PCECs.

Ni-based cermets have commonly been used as anode materials with good catalytic properties for hydrocarbon fuels. However, carbon deposition can occur due to the non-ideal electrochemical reaction of hydrocarbon fuel and the structural limitation resulting from the unsymmetrical Ni-based anode-supported single cells. This critical problem leads to loss of cell performance and poor long-term stability of solid oxide fuel cells (SOFCs). Our designed anode material with an extremely small amount (0.5 wt%) of Sn catalyst incorporated into the Ni and nano-composite structure was employed not only to prevent carbon deposition in oxygen deficient areas found for unsymmetrical cells, but also to increase the cell performance due to its excellent microstructure. The nano-composite Sn doped Ni-GDC cells showed a power density of 0.93 W cm À2 with stable operation in dry methane at 650 C. Sample CharacteristicsNi-GDC (NG) Mechanical mixture of Ni and the GDC cermet anode Sn doped Ni-GDC (SNG)Mechanical mixture of Sn doped Ni and the GDC cermet anode Ni/GDC-GDC (n-NGG) Nano-sized Ni and GDC conjugated on a core GDC nano-composite anode Sn doped Ni/GDC-GDC (n-SNGG) Sn doped nano-sized Ni and GDC conjugated on a core GDC nano-composite anode J. Mater. Chem. A This journal is