Liangmin Yu

Transparent Metal Selenide Alloy Counter Electrodes for High‐Efficiency Bifacial Dye‐Sensitized Solar Cells

The exploration of cost-effective and transparent counter electrodes (CEs) is a persistent objective in the development of bifacial dye-sensitized solar cells (DSSCs). Transparent counter electrodes based on binary-alloy metal selenides (M-Se; M=Co, Ni, Cu, Fe, Ru) are now obtained by a mild, solution-based method and employed in efficient bifacial DSSCs. Owing to superior charge-transfer ability for the I(-) /I3 (-) redox couple, electrocatalytic activity toward I3 (-) reduction, and optical transparency, the bifacial DSSCs with CEs consisting of a metal selenide alloy yield front and rear efficiencies of 8.30u2009% and 4.63u2009% for Co0.85 Se, 7.85u2009% and 4.37u2009% for Ni0.85 Se, 6.43u2009% and 4.24u2009% for Cu0.50 Se, 7.64u2009% and 5.05u2009% for FeSe, and 9.22u2009% and 5.90u2009% for Ru0.33 Se in comparison with 6.18u2009% and 3.56u2009% for a cell with an electrode based on pristine platinum, respectively. Moreover, fast activity onset, high multiple start/stop capability, and relatively good stability demonstrate that these new electrodes should find applications in solar panels.

Dissolution Engineering of Platinum Alloy Counter Electrodes in Dye‐Sensitized Solar Cells

The dissolution of platinum (Pt) has been one of the heart issues in developing advanced dye-sensitized solar cells (DSSCs). We present here the experimental realization of stable counter-electrode (CE) electrocatalysts by alloying Pt with transition metals for enhanced dissolution resistance to state-of-the-art iodide/triiodide (I(-)/I3(-)) redox electrolyte. Our focus is placed on the systematic studies of dissolution engineering for PtM0.05 (M=Ni, Co, Fe, Pd, Mo, Cu, Cr, and Au) alloy CE electrocatalysts along with mechanism analysis from thermodynamical aspects, yielding more negative Gibbs free energies for the dissolution reactions of transition metals. The competitive reactions between transition metals with iodide species (I3(-), I2) could protect the Pt atoms from being dissolved by redox electrolyte and therefore remain the high catalytic activity of the Pt electrode.

The morphology dependence of cuprous oxide and its photocatalytic properties

Cuprous oxide (Cu2O) micro-/nanocrystals were synthesized by a simple liquid phase reduction process with copper sulfate as a copper source and glucose monohydrate as a reducer. Detailed investigations of the temperature and feeding manners of the reagents on the morphology and particle size of Cu2O were carried out. X-ray diffraction patterns, morphology observations and ultraviolet–visible diffuse reflection absorption spectra were employed to characterize the crystallinity, morphology and light response. The characterization results gave three extraordinary morphologies: short hexapods, {110} truncated octahedron, and octahedron. The photocatalytic behaviors of the Cu2O crystals were evaluated by monitoring the degradation rate of methyl orange (MO), a target dye. An order for the light photocatalytic activities toward MO was determined: octahedron (diameter 0.172 μm) > short hexapods > octahedron (diameter 5.530 μm) > {110} truncated octahedron crystals. The bewitching structure, controllable morphology and robust photocatalytic performances as well as the easy synthesis mean that the Cu2O crystals are good candidates as light photocatalysts.

The feasibility and application of PPy in cathodic polarization antifouling

Cathodic polarization antifouling deserves attention because of its environmentally friendly nature and good sustainability. It has been proven that cathodic voltages applied on metal substrates exhibit outstanding antifouling effects. However, most metals immersed in marine environment are protected by insulated anticorrosive coatings, restricting the cathodic polarization applied on metals. This study developed a conducting polypyrrole (PPy)/acrylic resin coating (σu202f=u202f0.18u202fScm-1), which can be applied in cathodic polarization antifouling. The good stability and electro-activity of PPy in the negative polarity zone in alkalescent NaCl solution were verified by linear sweep voltammetry (LSV), chronoamperometry (CA), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), demonstrating the feasibility of PPy as cathodic polarization material. Furthermore, the antifouling effects of PPy/acrylicresin coating on 24-h old Escherichia coli bacteria (E. coli) which formed on PPy/acrylic resin-coated plastic plate were measured under different cathodic potentials and treatment time, characterized by fluorescent microscope. The results suggest that at cathodic potential around -0.5u202fV (vs. saturated calomel electrode (SCE)), there was little trace of attached bacteria on the substrate after 20u202fmin of treatment. PPy/acrylicresin-coated substrates were also subjected to repeated cycles of biofilm formation and electrochemical removal, where high removal efficiencies were maintained throughout the total polarization process. Under these conditions, the generation of hydrogen peroxide is believed to be responsible for the antifouling effects because of causing oxidative damage to cells, suggesting the potential of the proposed technology for application on insulated surfaces in various industrial settings.