Synthesis of Solvent-Mediated Morphology-Controlled PdSn Alloy Nanocatalysts and their Application in Electrocatalysis of Ethylene Glycol and Ethanol.

2D nanodendrites (NDs) and nanosheets (NSs) have been regarded as efficient nanocatalysts for enhancing the electrocatalytic performance due to their low coordinated sites and abundant electrocatalytic centers. Nevertheless, it remains challenging to construct advanced NDs and NSs in a single reaction system. Herein, by tuning the volume ratios of mixed solvents, the reduction and diffusion rate of Sn2+ on Pd NSs template was rationally controlled to prepare PdSn NDs and PdSn NSs. Ascribed to the open 2D nanostructure, high specific surface area, and robust synergistic effect, the as-prepared PdSn NDs and PdSn NSs exhibited distinguished electrocatalytic activities for ethylene glycol oxidation reaction (EGOR) and ethanol oxidation reaction (EOR), as well as commendable electrocatalytic durability, which were far superior to the Pd NSs and commercial Pd/C. In addition, the PdSn NDs exhibited enhanced reaction kinetics because the characteristic branch structure exposed a high density of active sites. This work may provide significant guidance for preparing excellent nanocatalysts with various morphological features by simply optimizing the content of the coexisting solvents.

In Situ Electrodeposition of Ultralow Pt into NiFe-Metal-Organic Framework/Nickel Foam Nanosheet Arrays as a Bifunctional Catalyst for Overall Water Splitting.

Exploring highly effective bifunctional electrocatalysts with surface structural advantages and synergistic optimization effects among multimetals is greatly important for overall water splitting. Herein, we successfully synthesized Pt-loaded NiFe-metal-organic framework nanosheet arrays grown on nickel foam (Pt-NiFe-MOF/NF) via a facile hydrothermal-electrodeposition process. Benefiting from large exposed specific surface, optimal electrical conductivity and efficient metal-support interaction endow Pt-NiFe-MOF/NF with highly catalytic performance, exhibiting small overpotential of 261 mV toward oxygen evolution reaction and 125 mV toward hydrogen evolution reaction at a current density of 100 mA cm-2 in alkaline medium. More significantly, the assembled water electrolyzer comprising the Pt-NiFe-MOF/NF//Pt-NiFe-MOF/NF couple demands a low cell voltage of 1.45 V to reach 10 mA cm-2. This work renders a viable approach to design dual-functional electrocatalysts with exceptional electrocatalytic activity and stability at high current density, showing the great prospect of water electrolysis for commercial application.

Photoelectrocatalytic oxidation of ethylene glycol on trimetallic PdAgCu nanospheres enhanced by surface plasmon resonance.

The notable surface plasmon resonance (SPR) effect of some metals has been applied to improve the efficiency of alcohol oxidation reactions, whereas the comprehensive investigation of Cu-assisted photoelectrocatalysis remains challenging. We herein successfully prepared trimetallic PdAgCu nanospheres (NSs) with abundant surface bulges for the advanced ethylene glycol oxidation reaction (EGOR) and compared them with bimetallic PdAg NSs to investigate the performance enhancement mechanism. Impressively, the as-optimized PdAgCu NSs exhibited superb mass activity and electrochemical stability. Moreover, under visible light illumination, the mass activity of PdAgCu NSs increased to 1.62 times compared to that in the dark, and in contrast, the mass activity of PdAg NSs only increased to 1.48 times that in the dark. A mechanistic study indicated that the incorporation of Cu not only strengthens the whole SPR effect of PdAgCu NSs but also further modifies the electronic structure of Pd. This work highlighted that the incorporation of Cu into PdAg NSs further enhanced the photoelectrocatalytic performance and increased noble metal atom utilization, which may provide guidance to fabricate novel and promising nanocatalysts in the field of photoelectrocatalysis.

Core@shell PtAuAg@PtAg Hollow Nanodendrites as Effective Electrocatalysts for Methanol and Ethylene Glycol Oxidation.

Pt-based catalysts with core@shell structures are widely used in alcohol oxidations due to their excellent catalytic performance. In this work, we synthesized a series of core@shell PtAuAg@PtAg hollow nanodendrites (HNDs) with different compositions by a simple seed-mediated method. The PtAuAg@PtAg HNDs with a hollow core and dendritic shell exhibit excellent catalytic performance for ethylene glycol oxidation reaction (EGOR) and methanol oxidation reaction (MOR). Among these, Pt38Au29Ag33 HNDs have the highest mass activity (12364.0 mA mgPt-1/3278.0 mA mgPt-1) for EGOR and MOR, which is 4.2 times and 5.3 times higher than that of commercial Pt/C (2941.0 mA mgPt-1/617.6 mA mgPt-1), respectively. More importantly, after successive cyclic voltammetry tests, the retained mass activities of Pt38Au29Ag33 HNDs are 3913.8 mA mgPt-1 and 348.3 mA mgPt-1, which are much higher than that of commercial Pt/C as well. The excellent catalytic performance of PtAuAg@PtAg HNDs can be attributed to the structure of HNDs, which can greatly increase the surface area and active sites, as well as the electronic and synergistic effects among Pt, Au, and Ag. This research may provide new ideas for the development of high-efficiency hollow catalytic materials for EGOR and MOR.

Synthesis and Properties of Moisture-Cured Reactive Polyurethane Containing Castor Oil and Oxime Compounds.

Reactive polyurethane hot-melt resin (moisture-cured reactive polyurethane, PUR) could successfully be prepared from poly(tetramethylene ether) glycol (PTMG), castor oil and dimethylglyoxime (DMG) by one or two-stage synthesis. Fourier-transform infrared spectroscopy (FTIR) analysis showed that the synthesis resins belonged to NCO-capped castor oil-based polyurethane. The thermal behaviors of the cured PUR were analyzed by differential scanning calorimeter (DSC) and dynamic mechanical analyzer (DMA) instruments. The results showed that the cured resin provided remeltable properties under the dosages of 3 wt% DMG. Furthermore, the phenomenon could be proved by FTIR analysis according to the characteristic absorption peak of NCO groups after the cured resin was heated. Comparing different syntheses, the resin prepared by one-stage synthesis showed random distribution of DMG with PUR structure and that prepared by two-stage synthesis had distribution of DMG with branching structure in the prepolymer. The former obtained lower remeltable temperatures from 90 to 130 °C than the latter temperatures, which had temperatures above 125 °C. The tensile test showed that all of the PUR films exhibited typical tough behavior. Thus, the cured resin with DMG dosages of 3 wt% provided remeltable and mechanical properties at the same time. Overall, the crosslinking density and numbers of dynamic bonds should be kept in balance for preparation of remeltable PUR.