Pt/IrO 2 bifunctional catalysts synthesized with varying Pt:Ir ratios and characterized using several techniques, including energy dispersive X-ray spectroscopy, transmission electrons microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy, were investigated for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in acid media. Three stability testing protocols are used to evaluate the catalysts stabilities, comprising electrode cycling in the ORR, OER, and ORR−OER potential ranges. Electrochemical results provide evidence that a Pt/IrO 2 1:9 material exhibits better balance between the OER and ORR mass activities and that cycling in the ORR-OER potential window is the most aggressive aging protocol for the Pt/IrO 2 materials. Identical location transmission electron microscopy is used to investigate the aging processes taking part in the Pt/IrO 2 catalysts. In addition to dissolution processes, particle coalescence, growth, and detachment are confirmed as responsible for the Pt/IrO 2 instability.

Application of oxide supports is considered as a viable approach to decrease iridium loading in oxygen evolution reaction catalysis in acid electrolyte. While the most of the promising oxides are poor conductors, the need for doping is typically taken as granted, and a representative example is tin dioxide. There are still, however, serious concerns on the feasibility of this approach as we lack consensus on any activity gain by using such oxides, while doubts on stability are numerous. In this work, a set of catalyst/support combinations including two catalysts, viz. hydrous (IrO x ) and rutile (IrO 2 ) iridium oxides, and four supports, viz. SnO 2 and Sb-(ATO), F-(FTO), and In-doped (ITO) SnO 2 , are synthesized and character-ized by a selection of complementary experimental techniques including rotating disk electrode and on-line inductively coupled plasma mass spectrometry. It is found that the electrochemical activity in acid media of supported Ir catalysts is essentially the same, independent on presence or absence of dopants. Sb and In dopants are shown to be unstable and cause an increased dissolution of Sn. Besides, the degradation of the doped supports results in destabilization of iridium oxides. These results raise doubts on the real need for the use of dopants in SnO 2 -based catalyst supports for electrochemical water splitting.

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Unitized regenerative fuel cells (URFCs) with Pt and Ir as catalysts can potentially provide required buffering capacity for the intermittent renewable energy. While a relatively good catalytic activity of Pt-Ir catalysts has been shown, data on dissolution stability is less convincing. In this work, two representative oxygen bifunctional catalysts for application in URFCs are synthesized by depositing Pt nanoparticles on hydrous Ir oxide (Pt/IrO x ) and rutile Ir oxide (Pt/IrO 2 ). A set of spectroscopy and microscopy techniques is used to characterize the synthesized materials. Regarding the catalytic activity, it is shown that Pt/IrO 2 and Pt/IrO x are superior for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), respectively. Further, the catalysts' stability toward dissolution is evaluated using a scanning flow cell coupled to an inductively coupled plasma mass spectrometer (SFC-ICP-MS) setup. Dissolution data reveal that Pt is relatively stable in either ORR or OER potential ranges. On the other hand, dissolution of Ir in the OER protocol is considerable. In the ORR-OER potential range, dissolution of both elements enhances significantly. Especially critical is high dissolution of Pt, which limits lifetime of the catalysts. These results must be considered in the development of novel bifunctional catalyst to be used in URFC.

Glycerol is a massive byproduct of biodiesel fabrication, which decreases its price and increases the risks of inadequate disposal. In this sense, more environmentally friendly instruments and processes using glycerol are required to make this matrix more valuable. Here, a 3D-printed electrolyzer was developed and tested for long-period glycerol electrolysis in an alkaline medium. The new electrolyzer contains only three mobile parts and can be manufactured in less than 4 h using ∼30 g of polylactic acid filament, with a total cost of less than US $5. This easily built and inexpensive reduced-scale electrolyzer has the advantage of using only a few milliliters of solution to perform tests for electrosynthesis. We synthesized Pd nanocubes to modify a glassy carbon working electrode, which was used for glycerol electrolysis. We found a remarkable selectivity of 99% toward tartronate production, which was induced by the extended (100) surface of Pd in the alkaline medium. Hence, we report a new 3D-printed platform for electrosynthesis and a new clean one-step method to produce tartronate.

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Available online xxxKeywords: Ethanol dehydrogenation Fuel blend Hydrogen PEMFC Catalysis a b s t r a c t This study aims at analyzing the potential application of the liquid effluent coming from a catalytic ethanol dehydrogenation reactor as a fuel blend or additive for internal combustion engines, and also of the hydrogen produced, as fuel for a polymer electrolyte fuel cell (PEMFC). The liquid effluent is obtained by the catalytic reaction of ethanol over Cu/ ZrO 2 at different contact times of the reactant with the catalyst bed. Subsequently, highperformance liquid chromatography analysis and heat of combustion measurements are used to analyze the composition and the heat of combustion of the liquid effluent trapped by cold condensation at 271.65 K. In parallel, the effect of the presence of residual parts of the constituents of the liquid effluent in the H 2 stream on the operational characteristics of a PEMFC having a Pt/C anode and cathode is investigated. Results show that the liquid fuel blend obtained from ethanol dehydrogenation has a heat of combustion higher than that of ethanol, and it is essentially formed by un-reacted ethanol, acetaldehyde and ethyl acetate.Thermodynamic calculations evidence a good agreement with the liquid effluent composition and its respective combustion enthalpy. Polarization curves of a PEMFC supplied with hydrogen containing 1000 ppm of acetaldehyde and ethyl acetate evidence performances comparable to that of the same system when fed with pure hydrogen, while with ethanol significant loss of activity is observed.