[MAT-25]Pseudo-cubic phase tungsten oxide as a photocatalyst for hydrogen evolution reaction

Defect and phase engineering can effectively tune the activity of photocatalysts by altering their band structure and active site configuration. Herein, we report the crystal phase-controlled synthesis of tungsten oxide (WO3) nanoplates by wet chemical approach. By adjusting the ratio of trioctylphosphine and trioctylphosphine oxide, oxygen vacancies are induced in WO3 accompanying the crystal structure transition from monoclinic to orthorhombic and pseudo-cubic phase. The experimental results and DFT calculations reveal that the increased oxygen vacant sites in WO3 leads to the upshift in both conduction band minimum and valence band maximum. The reformed band structure of reduced WO3 samples (WO3−x) enables the photocatalytic HER without the assistance of co-catalyst to achieve a maximum rate of 340 μmol g−1 h−1.

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[MAT-24]Two-dimensional porous nanosheets assembled by MoNx/Mo/CoMoy heterostructures for electrochemical hydrogen evolution reaction

2D porous non-layered MoNx/Mo/CoMoy heterostructures have been fabricated by using 2D layered cobalt doped ZnMo layered nanosheets as the starting materials. The 2D morphology is well remained after heat treatment of the precursors in reducing atmosphere. The intrinsic activity is improved by constructing the heterostructures, which exhibit higher HER activity than that of their single-phase counterparts.

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[MAT-22]Local functionalization of a digital microfluidic device with an antimicrobial polydopamine coating

The hydrophobic surface on the top plate of digital microfluidic device was locally modified via the polydopamine film. There are four critial variables that directly affect the roughness, thickness and size of polydopamine film including concentration of dopamine solution, incubation time, deposition method and the volume of dopamine solution. High concentration and two-step incubation contributes to a higher roughness of polydopamine film quantified with 3D Surface Metrology.

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[MAT-21]A low-potential, low molecular weight boron-based anolyte for nonaqueous redox flow batteries

The development of non-aqueous redox flow batteries (NARFBs) were believed as the potential device for sustainable energy storage due to its wide electrochemical windows ( >5V), marching to high energy density ( >50Wh/L). Herein, we report the first examples of using boron ß-diketonates as anolyte in NARFBs. The di-tert-butyl derivative tBuBF2 exhibited superior redox reversibility at -1.83V with high solubility of 2.0M in acetonitrile. Coupling with the catholyte DBMMB, the RFBs demonstrated an exceptionally high cell voltage of 2.57V over 100 cycles with high theoretical energy density of 69 Wh/L, verifying tBuBF2 is a promising electroactive anolyte for NARFBs.

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[MAT-20]Quantifying electron transfer kinetics on porous carbon electrodes for redox flow batteries

Despite the critical role of electron transfer kinetics in determining the energy efficiency and the power density of a redox flow battery (RFB), there has not been much progress quantifying the kinetics on commercial porous carbon electrodes, the most common RFB electrodes with no immediate planar-electrode counterparts for cyclic voltammetry (CV) analyses. Here, we tackle this challenge by encapsulating porous carbon electrodes in epoxy, whose cross-sections are used for CV analyses. These electrodes display behaviors of micro-electrodes with length scales characteristic of fibers in the original porous structures. We thereby characterize the kinetics of ferricyanide reduction and corroborate these findings with symmetric RFB tests. The method developed here provides a much-needed assessment of kinetics on porous carbon electrodes free from the impacts of mass transports in the pores, enabling the identification of performance-determining factors of RFB electrodes.

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[MAT-19]High capacity electrolytes for redox flow batteries

In this poster we show our work on learning the factor that influence the anthraquinone derivatives’ solubility. We found that cation’s hydration energy and lattice energy have the major influence. Based on these results we made the solubility correlation between sulfate and sulfonate salts. With this correlation, we successfully prepared the high solubility vanadium-2,7-anthraquinone hybrid electrolyte. Battery test showed that the hybrid electrolyte can achieve high capacity and good cycling performance.

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