Herein we investigate the effect of irreversibly adsorbed bismuth on polycrystalline platinum (Pt p) on the electrooxidation of glycerol in alkaline media by combining electrochemical, spectroscopic (in situ FTIR) and analytical (HPLC on line) techniques. We found that the activity of Pt p increases by about fivefold when the optimal quantity of Bi ions is added to the solution. Besides, the adatom strongly impacts the reaction products by suppressing the pathways with CC bond breaking, hindering the formation of CO (and other unknown intermediates) and enhancing the production of Glycerate. Different to the results in acid media for Pt p-Bi systems where Bi block the oxidation pathway through the primary carbon, glycerate is the main product in alkaline media and dihydroxyacetone is either produced in extremely low quantities or not produced. Besides, comparing our results with those in acid media, the peak current recorded at 1 mV.s-1 in this work was one order of magnitude higher. These results show the strong impact of the pH in the reaction rate and selectivity.

Herein we investigated the effect of the adsorption of Bi and Pb on polycrystalline platinum (Pt p ) on the electrooxidation of glycerol (EOG) in alkaline media by combining electrochemical, spectroscopic (in situ FTIR), and analytical (online HPLC) techniques. Besides, we used single crystal Pt electrodes to understand the effect of the modification of Pt p in terms of the atomic arrangements on its surface. We found that the activity of Pt p increases in the presence of Pb (Pt p −Pb), which acts by suppressing the pathways with complete CC bond breaking (to produce carbonate) and enhancing the production of glycerate, formate, tartronate, and glycolate. We also found that Pt(100) and Pt(111) are affected by the adsorption of both adatoms. However, the modification of Pt(110) explains the results obtained with Pt p . This basal plane is highly activated by Bi and Pb and its behavior is similar to those of Pt p −Bi and Pt p −Pb, respectively. These results permit the conclusion that the adatoms acts mainly by activating Pt atoms with low coordination, which generally binds the adsorbates more strongly and, in consequence, suffers more from poisoning. The adatoms act by preventing the formation of multiple bonded intermediates, likely through a combination of a third body effect and also to a change in the electronic configuration at the surface of the catalyst. We propose in this work that the higher promotion of the EOG by the adatoms in alkaline media is due to a stabilization of the negatively charged intermediates by the Coulombic interaction with the positively charged adatoms.

Electrocatalysis is at the heart of a broad range of physicochemical applications that play an important role in the present and future of a sustainable economy. Among the myriad of different electrocatalysts used in this field, nanomaterials are of ubiquitous importance. An increased surface area/volume ratio compared to bulk makes nanoscale catalysts the preferred choice to perform electrocatalytic reactions. Bragg coherent diffraction imaging (BCDI) was introduced in 2006 and since has been applied to obtain 3D images of crystalline nanomaterials. BCDI provides information about the displacement field, which is directly related to strain. Lattice strain in the catalysts impacts their electronic configuration and, consequently, their binding energy with reaction intermediates. Even though there have been significant improvements since its birth, the fact that the experiments can only be performed at synchrotron facilities and its relatively low resolution to date (∼10 nm spatial resolution) have prevented the popularization of this technique. Herein, we will briefly describe the fundamentals of the technique, including the electrocatalysis relevant information that we can extract from it. Subsequently, we review some of the computational experiments that complement the BCDI data for enhanced information extraction and improved understanding of the underlying nanoscale electrocatalytic processes. We next highlight success stories of BCDI applied to different electrochemical systems and in heterogeneous catalysis to show how the technique can contribute to future studies in electrocatalysis. Finally, we outline current challenges in spatiotemporal resolution limits of BCDI and provide our perspectives on recent developments in synchrotron facilities as well as the role of machine learning and artificial intelligence in addressing them.

Shedding synchrotron light on microfluidic systems, exploring several contrasts in situ/operando at the nanoscale, like X-ray fluorescence, diffraction, luminescence, and absorption, has the potential to reveal new properties and functionalities of materials across diverse areas, such as green energy, photonics, and nanomedicine. In this work, we present the micro-fabrication and characterization of a multifunctional polyester/glass sealed microfluidic device well-suited to combine with analytical X-ray techniques. The device consists of smooth microchannels patterned on glass, where three gold electrodes are deposited into the channels to serve in situ electrochemistry analysis or standard electrical measurements. It has been efficiently sealed through an ultraviolet-sensitive sticker-like layer based on a polyester film, and The burst pressure determined by pumping water through the microchannel(up to 0.22 MPa). Overall, the device has demonstrated exquisite chemical resistance to organic solvents, and its efficiency in the presence of biological samples (proteins) is remarkable. The device potentialities, and its high transparency to X-rays, have been demonstrated by taking advantage of the X-ray nanoprobe Carnaúba/Sirius/LNLS, by obtaining 2D X-ray nanofluorescence maps on the microchannel filled with water and after an electrochemical nucleation reaction. To wrap up, the microfluidic device characterized here has the potential to be employed in standard laboratory experiments as well as in in situ and in vivo analytical experiments using a wide electromagnetic window, from infrared to X-rays, which could serve experiments in many branches of science.

Shedding synchrotron light on microfluidic systems, exploring several contrasts in situ operando at the nanoscale, like X-ray fluorescence, diffraction, luminescence, and absorption, has the potential to reveal new properties and functionalities of materials across diverse areas, such as green energy, photonics, and nanomedicine. In this work, we present the micro-fabrication and characterization of a multifunctional polyester/glass sealed microfluidic device well-suited to combine with analytical X-ray techniques. The device consists of smooth microchannels patterned on glass, where three gold electrodes are deposited into the channels to serve in situ electrochemistry analysis or standard electrical measurements. It has been efficiently sealed through an ultraviolet-sensitive sticker-like layer based on a polyester film, and The burst pressure determined by pumping water through the microchannel(up to 0.22 MPa). Overall, the device has demonstrated exquisite chemical resistance to organic solvents, and its efficiency in the presence of biological samples (proteins) is remarkable. The device potentialities, and its high transparency to X-rays, have been demonstrated by taking advantage of the X-ray nanoprobe Carnaúba/Sirius/LNLS, by obtaining 2D X-ray nanofluorescence maps on the microchannel filled with water and after an electrochemical nucleation reaction. To wrap up, the microfluidic device characterized here has the potential to be employed in standard laboratory experiments as well as in situ and in vivo analytical experiments using a wide electromagnetic window, from infrared to X-rays, which could serve experiments in many branches of science.