Mingshi Jin

A New Mussel‐Inspired Polydopamine Sensitizer for Dye‐Sensitized Solar Cells: Controlled Synthesis and Charge Transfer

The efficient electron injection by direct dye-to-TiO(2) charge transfer and strong adhesion of mussel-inspired synthetic polydopamine (PDA) dyes with TiO(2) electrode is demonstrated. Spontaneous self-polymerization of dopamine using dip-coating (DC) and cyclic voltammetry (CV) in basic buffer solution were applied to TiO(2) layers under a nitrogen atmosphere, which offers a facile and reliable synthetic pathway to make the PDA dyes, PDA-DC and PDA-CV, with conformal surface and perform an efficient dye-to-TiO(2) charge transfer. Both synthetic methods led to excellent photovoltaic results and the PDA-DC dye exhibited larger current density and efficiency values than those in the PDA-CV dye. Under simulated AM 1.5 G solar light (100 mW cm(-2)), a PDA-DC dye exhibited a short circuit current density of 5.50 mW cm(-2), corresponding to an overall power conversion efficiency of 1.2 %, which is almost 10 times that of the dopamine dye-sensitized solar cell. The PDA dyes showed strong adhesion with the nanocrystalline TiO(2) electrodes and the interface engineering of a dye-adsorbed TiO(2) surface through the control of the coating methods, reaction times and solution concentration maximized the overall conversion efficiency, resulting in a remarkably high efficiency.

Discovery of abnormal lithium-storage sites in molybdenum dioxide electrodes

Developing electrode materials with high-energy densities is important for the development of lithium-ion batteries. Here, we demonstrate a mesoporous molybdenum dioxide material with abnormal lithium-storage sites, which exhibits a discharge capacity of 1,814 mAh g−1 for the first cycle, more than twice its theoretical value, and maintains its initial capacity after 50 cycles. Contrary to previous reports, we find that a mechanism for the high and reversible lithium-storage capacity of the mesoporous molybdenum dioxide electrode is not based on a conversion reaction. Insight into the electrochemical results, obtained by in situ X-ray absorption, scanning transmission electron microscopy analysis combined with electron energy loss spectroscopy and computational modelling indicates that the nanoscale pore engineering of this transition metal oxide enables an unexpected electrochemical mass storage reaction mechanism, and may provide a strategy for the design of cation storage materials for battery systems.

Indoor formaldehyde removal over CMK-3

The removal of formaldehyde at low concentrations is important in indoor air pollution research. In this study, mesoporous carbon with a large specific surface area was used for the adsorption of low-concentration indoor formaldehyde. A mesoporous carbon material, CMK-3, was synthesized using the nano-replication method. SBA-15 was used as a mesoporous template. The surface of CMK-3 was activated using a 2N H2SO4 solution and NH3 gas to prepare CMK-3-H2SO4 and CMK-3-NH3, respectively. The activated samples were characterized by N2 adsorption-desorption, X-ray diffraction, and X-ray photoelectron spectroscopy. The formaldehyde adsorption performance of the mesoporous carbons was in the order of CMK-3-NH3 > CMK-3-H2SO4 > CMK-3. The difference in the adsorption performance was explained by oxygen and nitrogen functional groups formed during the activation process and by the specific surface area and pore structure of mesoporous carbon.

Catalytic ozone oxidation of benzene at low temperature over MnOx/Al-SBA-16 catalyst

The low-temperature catalytic ozone oxidation of benzene was investigated. In this study, Al-SBA-16 (Si/Al = 20) that has a three-dimensional cubic Im3m structure and a high specific surface area was used for catalytic ozone oxidation for the first time. Two different Mn precursors, i.e., Mn acetate and Mn nitrate, were used to synthesize Mn-impregnated Al-SBA-16 catalysts. The characteristics of these two catalysts were investigated by instrumental analyses using the Brunauer-Emmett-Teller method, X-ray diffraction, X-ray photoelectron spectroscopy, and temperature-programmed reduction. A higher catalytic activity was exhibited when Mn acetate was used as the Mn precursor, which is attributed to high Mn dispersion and a high degree of reduction of Mn oxides formed by Mn acetate than those formed by Mn nitrate.

In situ-generated metal oxide catalyst during CO oxidation reaction transformed from redox-active metal-organic framework-supported palladium nanoparticles

The preparation of redox-active metal-organic framework (ra-MOF)-supported Pd nanoparticles (NPs) via the redox couple-driven method is reported, which can yield unprotected metallic NPs at room temperature within 10 min without the use of reducing agents. The Pd@ra-MOF has been exploited as a precursor of an active catalyst for CO oxidation. Under the CO oxidation reaction condition, Pd@ra-MOF is transformed into a PdOx-NiOy/C nanocomposite to generate catalytically active species in situ, and the resultant nanocatalyst shows sustainable activity through synergistic stabilization.

Redox-buffer effect of Fe2+ ions on the selective olefin/paraffin separation and hydrogen tolerance of a Cu+-based mesoporous adsorbent

In the present work, a new mesoporous adsorbent containing ferrous/cuprous ionic species (Fe–Cu/MCM-41) has been developed for selective separation of 1-butene/n-butane. Co-impregnation of Fe2+ ions with Cu+ ions within mesopores gives superior 1-butene/n-butane separation ability. Fe–Cu/MCM-41 exhibits much higher heat of adsorption for 1-butene (−23.4 kJ mol−1) compared to that of Cu/MCM-41 (−11.2 kJ mol−1), resulting in a larger adsorption amount of 1-butene over Fe–Cu/MCM-41 (4.4 mmol g−1 at 1 atm) than that over Cu/MCM-41 (2.8 mmol g−1 at 1 atm). The results indicate that Fe–Cu/MCM-41 exhibits superior π-complexation ability for 1-butene than Cu/MCM-41. Moreover, the adsorption ability of Fe–Cu/MCM-41 does not change very much upon H2-treatment at different temperatures in the range of 273 K to 473 K, revealing the excellent hydrogen tolerance of the adsorbent. Physicochemical analyses indicated that the existence of Fe2+ species prevented the oxidation and reduction of Cu+ species during the adsorbent preparation and during the separation process in the presence of a reducing gas such as hydrogen, i.e., the Fe2+ species may act as a kind of redox buffer in the Fe–Cu/MCM-41 adsorbent for improving the chemical stability of Cu+ species that are highly effective for π-complexation with olefin.

Fixation of Carbon Nanotube Within Mesoporous Titania Particles

Carbon nanotube (CNT) and mesoporous TiO2 composite (CNT/meso-TiO2) was synthesized by a nanocasting method using CNT-implanted mesoporous silica material as the template. The CNT was successfully incorporated within a mesoporous TiO2 particle, and the CNT/meso-TiO2 composite obtained exhibits a high surface area and well-established mesoporosity. Moreover, the composite material exhibits much lower electric resistance than those of mesoporous TiO2 only and physical mixture of CNT and mesoporous TiO2, which probably due to the large interface area and strong junction between the implanted CNT and TiO2 framework in the composite.