Diego González-Quijano

Pt-Sn/C and Pt-Ru/C electrocatalysts were synthesized by a polyol method at nominal atomic ratios of 1:1, 2:1, and 3:1, and evaluated for the ethanol oxidation reaction (EOR) and ethylene glycol oxidation reaction (EGOR) in alkaline media. EDS confirmed compositions close to the nominal values, XRD evidenced fcc Pt-M alloy formation, and ADF-STEM revealed well-dispersed nanoparticles below 3 nm. Cyclic voltammetry showed that both Sn and Ru enhance activity relative to Pt/C: Pt-Sn_1:1 delivered the highest forward current density in the Sn series (1486 mA mg⁻¹_Pt for EOR; 2583 mA mg⁻¹_Pt for EGOR), whereas Pt-Ru shifted the onset to more negative potentials (down to −539 mV vs. SHE for EOR), with Pt-Ru_3:1 reaching 1858 (EOR) and 2434 mA mg⁻¹_Pt (EGOR). Chronoamperometry revealed higher current retention during EGOR than EOR for all catalysts, indicating fewer poisoning intermediates from ethylene glycol. DFT calculations of CO adsorption on 1:1 and 3:1 model surfaces rationalize the distinct roles of the two metals: Sn excludes CO from Sn sites at both compositions and weakens the Pt-CO bond by 0.602 eV at 1:1, while Ru weakens it moderately yet binds CO strongly at both compositions; the bifunctional supply of OH_ads by Ru, inferred from the more negative onset potentials, accounts for its higher activity. PDOS analysis links these trends to distinct Pt d-band modifications.

To reduce the CO₂ concentration in the atmosphere, its conversion to different value-added chemicals plays a very important role. Nevertheless, the stable nature of this molecule limits its conversion. Therefore, the design of highly efficient and selective catalysts for the conversion of CO₂ to value-added chemicals is required. Hence, in this work, the CO₂ adsorption on Pt_4-xCu_x (x = 0–4) sub-nanoclusters deposited on pyridinic N-doped graphene (PNG) was studied using the density functional theory. First, the stability of Pt_4-xCu_x (x = 0–4) sub-nanoclusters supported on PNG was analyzed. Subsequently, the CO₂ adsorption on Pt_4-xCu_x (x = 0–4) sub-nanoclusters deposited on PNG was computed. According to the binding energies of the Pt_4-xCu_x (x = 0–4) sub-nanoclusters on PNG, it was observed that PNG is a good material to stabilize the Pt_4-xCu_x (x = 0–4) sub-nanoclusters. In addition, charge transfer occurred from Pt_4-xCu_x (x = 0–4) sub-nanoclusters to the PNG. When the CO₂ molecule was adsorbed on the Pt_4-xCu_x (x = 0–4) sub-nanoclusters supported on the PNG, the CO₂ underwent a bond length elongation and variations in what bending angle is concerned. In addition, the charge transfer from Pt_4-xCu_x (x = 0–4) sub-nanoclusters supported on PNG to the CO₂ molecule was observed, which suggests the activation of the CO₂ molecule. These results proved that Pt_4-xCu_x (x = 0–4) sub-nanoclusters supported on PNG are adequate candidates for CO₂ adsorption and activation.

In the present work, photoanodes for dye-sensitised solar cell (DSSC) composed of SnO₂ nanoparticles were developed by electrophoretic deposition (EPD) process . Taguchi experimental design was adopted to investigate the effect of EPD parameters into the physical and chemical properties of the deposited film. The deposited photoanodes were characterized by scanning electron microscopy (SEM) and optical microscope. Also, electrical measurements were conducted with the aim to evaluate the effect of the deposition parameters on the DSSC current density. The experimental results reveal that magnesium nitrate concentration has the most significant effect on the photocurrent densities followed by the time of deposition. It has been observed that the deposition parameters studied greatly influence the morphology of the obtained film. This indicates that the electrophoretic deposition process under a Taguchi design orthogonal array might be a cost efficient method to develop anodes for DSSC.

Pt−Sn/C electrocatalysts with nominal Pt : Sn atomic ratios of 1 : 1, 2 : 1 and 3 : 1 were synthesized via the polyol method. The effects of the atomic ratios on their catalytic activity for the ethanol oxidation reaction (EOR) in acidic media was evaluated and compared to a Pt/C electrocatalyst obtained by the same procedure. The differences in reaction mechanism between the alloys and Pt/C were elucidated by in‐situ FTIR measurements. XRD characterization of the Pt−Sn/C electrocatalysts showed a degree of alloying ranging between 27 and 54 % (from Vegard's law), while crystallite sizes close to 2.2 nm were determined with the Scherrer equation. Pt : Sn atomic ratios of 1 : 1, 1.6 : 1 and 2.4 : 1 were found experimentally via EDS analysis, fairly close to the nominally expected values. Electrochemical evaluation indicated that the alloy having a 1 : 1 ratio has the highest electrocatalytic activity for EOR. In‐situ FTIR characterization showed that the Pt−Sn/C alloys promote the oxidation of ethanol via a triple parallel pathway: one path involving the directly conversion of CO_L (linearly‐bonded CO) to CO₂, while the second proceeds via the reaction of AAL (acetaldehyde) into CO_L and later to CO₂, and the third involves the formation of AA (acetic acid) from adsorbed acetate that may be produced from AAL. Such mechanism promoted the EOR at more negative potentials at the alloys, also delivering higher current densities, relative to Pt/C. Thus, the inclusion of Sn in the Pt structure enhanced the catalytic activity for the EOR in acidic media.