A comprehensive development of the charge-transfer theory of surface enhanced Raman scattering (SERS) is presented. We incorporate the Herzberg–Teller mixing of zero-order Born–Oppenheimer electronic states by means of vibronic interaction terms in the Hamiltonian. This is similar to the theory of Tang and Albrecht12 except that we include metal states as part of a molecule–metal system. When this is done we may no longer discard a term involving mixing of ground-state vibrations. The theory is comprehensive in that both molecule-to-metal and metal-to-molecule transfer is considered. Furthermore, both Franck–Condon and Herzberg–Teller contributions to the intensity are obtained. The former, however, contribute only to the intensity of totally symmetric vibrations, while the latter contribute to nontotally symmetric vibrations as well. Since overtones are observed in SERS only weakly if at all, the Herzberg–Teller terms are most consistent with experimental findings. The resulting formulas may be interpreted as a type of resonance Raman effect in which intensity for the charge transfer transitions is borrowed from an allowed molecular transition. We may also carry out the sum over metal states. This procedure predicts a logarithmic resonance at the Fermi level of the metal. We thus predict intensity vs voltage profiles such as I ∝ ‖ln(ωFI−ω+iΓ)‖2 which fits the experimental curves quite well.

Over the past few decades, direct methanol fuel cells (DMFCs) have been intensively developed as clean and high-efficiency energy conversion devices. However, their dependence on expensive Pt-based catalysts for both the anode and the cathode make them unsuitable for large-scale commercialisation. The essential solution to addressing this shortfall is the development of low-Pt and non-Pt catalysts. Regarding this issue, considerable advances have been made with low-Pt alloys and core-shell-like catalysts, as well as non-platinum Pd-Me, Ru-Se and heat-treated MeN x C y -based catalysts. This perspective reviews potential pathways for increasing the cost-effectiveness and efficiency of these catalysts. Fundamental understanding of the composition-activity and structure-activity relationships, innovative synthesis, and promising developmental directions are highlighted. Regarding durability, the main degradation mechanism of these catalysts and the corresponding mitigating strategies are presented.

Pd-Au/C and Pd-Ag/C were found to have a unique characteristic of evolving high-quality hydrogen dramatically and steadily from the catalyzed decomposition of liquid formic acid at convenient temperature, and further this was improved by the addition of CeO(2)(H(2)O)(x).

A new electrocatalyst, palladium nanoparticle-single-walled carbon nanotube (Pd-SWNTs) hybrid nanostructure, for the nonenzymatic oxidation of glucose was developed and characterized by X-ray diffraction (XRD) and the transmission electron microscope (TEM). The hybrid nanostructures were prepared by depositing palladium nanoparticles with average diameters of 4-5 nm on the surface of single-walled carbon nanotubes (SWNTs) via chemical reduction of the precursor (Pd(2+)). The electrocatalyst showed good electrocatalytic activity toward the oxidation of glucose in the neutral phosphate buffer solution (PBS, pH 7.4) even in the presence of a high concentration of chloride ions. A nonenzymatic amperometric glucose sensor was developed with the use of the Pd-SWNT nanostructure as an electrocatalyst. The sensor had good electrocatalytic activity toward oxidation of glucose and exhibited a rapid response (ca.3 s), a low detection limit (0.2 +/- 0.05 microM), a wide and useful linear range (0.5-17 mM), and high sensitivity (approximately 160 microA mM(-1) cm(-2)) as well as good stability and repeatability. In addition, the common interfering species, such as ascorbic acid, uric acid, 4-acetamidophenol, 3,4-dihydroxyphenylacetic acid, and so forth did not cause any interference due to the use of a low detection potential (-0.35 V vs SCE). The sensor can also be used for quantification of the concentration of glucose in real clinical samples. Therefore, this work has demonstrated a simple and effective sensing platform for nonenzymatic detection of glucose.