Selective Conversion of Propane by Electrothermal Catalysis in Proton Exchange Membrane Fuel Cell.

Electrochemical conversion of alkanes to high value-added oxygenated products under a mild condition is of significance. Herein, we effectively couple the electrocatalysis of H2 O2 with the thermo-catalysis of propane oxidation in the cathode of proton exchange membrane fuel cell. Specifically, H2 O2 is in-situ generated on the nitric acid-treated carbon black (C-acid) via 2e- process of oxygen reduction reaction, and then transports to the Fe active sites of MIL-53 (Al, Fe) metal-organic frameworks for propane oxidation. Based on this strategy, the space-time yield of C3 oxygenated products of propane oxidation reaches 2.65 µmol h-1 cm-2 , which represents a new benchmark for electrochemical alkane oxidation in the fuel-cell-type electrolyzer. This study highlights the importance of multifunctional composite catalysts in the field of electrosynthesis.

Reaction Mechanism and Selectivity Tuning of Propene Oxidation at the Electrochemical Interface.

Electrochemical conversion of propene is a promising technique for manufacturing commodity chemicals by using renewable electricity. To achieve this goal, we still need to develop high-performance electrocatalysts for propene electrooxidation, which highly relies on understanding the reaction mechanism at the molecular level. Although the propene oxidation mechanism has been well investigated at the solid/gas interface under thermocatalytic conditions, it still remains elusive at the solid/liquid interface under an electrochemical environment. Here, we report the mechanistic studies of propene electrooxidation on PdO/C and Pd/C catalysts, considering that the Pd-based catalyst is one of the most promising electrocatalytic systems. By electrochemical in situ attenuated total reflection Fourier transform infrared spectroscopy, a distinct reaction pathway was observed compared with conventional thermocatalysis, emphasizing that propene can be dehydrogenated at a potential higher than 0.80 V, and strongly adsorb via µ-C═CHCH3 and µ3-η2-C═CHCH3 configuration on PdO and Pd, respectively. The µ-C═CHCH3 is via bridge bonds on adjacent Pd and O atoms on PdO, and it can be further oxidized by directly taking surface oxygen from PdO, verified by the H218O isotope-edited experiment. A high surface oxygen content on PdO/C results in a 3 times higher turnover frequency than that on Pd/C for converting propene into propene glycol. This finding highlights the different reaction pathways under an electrochemical environment, which sheds light on designing next-generation electrocatalysts for propene electrooxidation.

Local Structure Modulation Induced Highly Efficient Far-Red Luminescence of La1- xLu xAlO3:Mn4+ for Plant Cultivation.

Modulating the local environment around the emitting ions with component screening to increase the quantum yield and thermal stability is an effective and promising strategy for the design of high-performance fluorescence materials. In this work, smaller Lu3+ was introduced into the La3+ site in a Mn4+-activated LaAlO3 phosphor with the expectation of improving the luminescence properties via lattice contraction induced by cation substitution. Finally, a La1- xLu xAlO3:Mn4+ ( x = 0-0.04) perovskite phosphor with a high quantum yield of 86.0% and satisfactory thermal stability was achieved, and the emission peak at 729 nm well matches with the strongest absorption peak of the Phytochrome PFR. The favorable performances could be attributed to the suppressed cell volume and superior lattice rigidity after the substitution of Lu3+. This work not only obtains a highly efficient La1- xLu xAlO3:Mn4+ ( x = 0.02) phosphor, which holds great potential for application in plant-cultivation light-emitting diodes, but also provides an applicable strategy for further investigation of far-red-emitting phosphors.

A highly luminescent Mn4+ activated LaAlO3 far-red-emitting phosphor for plant growth LEDs: charge compensation induced Mn4+ incorporation.

As a potential far-red-emitting candidate for plant growth LEDs, Mn4+ activated oxide phosphors have brand-new application prospects. However, it remains a significant challenge to develop highly efficient far-red-emitting phosphors due to their intrinsic energy loss in a large Stokes shift. Herein, we present a rational charge compensation strategy with a fusible charge compensator MgF2 at the molecular level to synthesize a LaAlO3:Mn4+,Mg2+ far-red-emitting phosphor. Notably, MgF2 can play an essential role in the incorporation of Mn4+ into the crystal matrix during the high-temperature solid-state reaction process, and thus induce a highly luminescent phosphor with a quantum yield of 78.6% and appropriate thermal stability. The fabrication of a high-performance far-red-emitting phosphor-converted LED further identifies the application potential of the modified Mn4+ activated LaAlO3 phosphor. This finding sheds light on the further exploration of high-grade far-red phosphors.