One-pot synthesis of ultrafine decahedral platinum crystal decorated graphite nanosheets for the electro-oxidation of formic acid

Recent Advances of Electrocatalysts and Electrodes for Direct Formic Acid Fuel Cells: from Nano to Meter Scale Challenges

Direct formic acid fuel cells are promising energy devices with advantages of low working temperature and high safety in fuel storage and transport. They have been expected to be a future power source for portable electronic devices. The technology has been developed rapidly to overcome the high cost and low power performance that hinder its practical application, which mainly originated from the slow reaction kinetics of the formic acid oxidation and complex mass transfer within the fuel cell electrodes. Here, we provide a comprehensive review of the progress around this technology, in particular for addressing multiscale challenges from catalytic mechanism understanding at the atomic scale, to catalyst design at the nanoscale, electrode structure at the micro scale and design at the millimeter scale, and finally to device fabrication at the meter scale. The gap between the highly active electrocatalysts and the poor electrode performance in practical devices is highlighted. Finally, perspectives and opportunities are proposed to potentially bridge this gap for further development of this technology.

Coupling Glycerol Conversion with Hydrogen Production Using Alloyed Electrocatalysts

Herein, uniform precious alloys including PtAg, PdAg, and PtPdAg nanoparticles were synthesized as electrocatalysts for glycerol oxidation reaction (GOR). The structures of the samples were characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectrometry. The catalytic performance of the samples was evaluated in both alkaline and acidic electrolytes. Among the samples, PtPdAg exhibited superior activity with the largest current density of 3.77 mA cm-2 in alkaline solutions, which is 4.1 and 7.7 times those of Pd/C and Pt/C, respectively. In acidic solutions, the PtPdAg catalyst shows the highest current density of 0.58 mA cm-2, which is 1.8 times that of the Pt/C catalyst. The products of GOR were analyzed by high-performance liquid chromatography. Eight products including oxalic acid, tartronic acid, glyoxylic acid, glyceric acid, glyceraldehyde (GLAD), glycolic acid, lactic acid, and dihydroxyacetone were detected. Notably, in acidic solutions, PtAg and PtPdAg yielded the largest GLAD selectivity of 92.2% at 0.6 and 0.8 V, respectively. Using the alloyed catalysts, electrolysis processes coupling the GOR with the hydrogen evolution reaction were conducted. The conversion of glycerol and production of hydrogen were determined. To highlight the energy efficiency, a solar-panel-powered electrolysis process was conducted for the simultaneous production of hydrogen and high-valued products.

Selective Electro-Oxidation of Glycerol to Dihydroxyacetone by PtAg Skeletons

Developing high-performance electrocatalysts for the selective conversion of glycerol into value-added chemicals is of great significance. Herein, three-dimensional nanoporous PtAg skeletons were studied as catalysts for the electro-oxidation of glycerol. The structural features of the PtAg skeletons were revealed by electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV-vis spectroscopy. The electrochemical activity of the catalysts was examined by cyclic voltammetry, linear sweeping voltammetry, and chronoamperometry. The resulting PtAg skeletons exhibit a peak current density of 7.57 mA cm^-2, which is 15.4-fold higher than that of Pt/C, making the PtAg skeletons one of the best electrocatalysts for glycerol oxidation. High-performance liquid chromatography results show that the PtAg skeletons yield a remarkable dihydroxyacetone selectivity of 82.6%, which has so far been the second largest value reported in the literature. The superior activity and selectivity of the PtAg skeletons are ascribed to the large surface area and abundant Pt(111) facets. Additionally, the effects of glycerol and KOH concentrations and reaction time on product selectivity were investigated.