Dynamics of Weak, Bifurcated, and Strong Hydrogen Bonds in Lithium Nitrate Trihydrate

The properties of three distinct types of hydrogen bonds, namely a weak, a bifurcated, and a strong one, all present in the LiNO₃·(HDO)(D₂O)₂ hydrate lattice unit cell are studied using steady-state and time-resolved spectroscopy. The lifetimes of the OH stretching vibrations for the three individual bonds are 2.2 ps (weak), 1.7 ps (bifurcated), and 1.2 ps (strong). For the first time, the properties of bifurcated H bonds can thus be unambiguously directly compared to those of weak and strong H bonds in the same system. The values of their OH stretching vibration lifetime, anharmonicity, red shift, and bond strength lie between those for the strong and weak H bonds. The experimentally observed inhomogeneous broadening of their spectral signature can be partly attributed to the coupling with a low frequency intermolecular wagging vibration

Is Base-Inhibited Vapor Phase Polymerized PEDOT an Electrocatalyst for the Hydrogen Evolution Reaction? Exploring Substrate Effects, Including Pt Contaminated Au

Studies of the hydrogen evolution reaction (HER) were carried out on base-inhibited vapor phase polymerized (BI-VPP) poly(3,4-ethylenedioxythiophene) (PEDOT)-poly(ethylene glycol) (PEG) thin films synthesized on several substrates, including gold, glassy carbon, and titanium, in an acidic electrolyte. The proton reduction overpotential became smaller and the current potential (i-E) scans moved toward the thermodynamic potential with time. However, they did not move below the proton reduction potential of the substrate. Collectively, the results suggested to us that the polymer film was porous and that the porosity increased with time when the electrode was immersed in solution, with the hydrogen evolution catalysis taking place on the conducting substrate beneath the polymer rather than on our BI-VPP PEDOT-PEG thin films. Comparison of the HER on gold substrates with different impurities was also studied and traces of Pt and Pd at the ppm level significantly improved the HER activity of Au