Alcohols are highly common organic compounds but remain scarce as alkyl donors in synthetic procedures. Here, we describe an electrochemical procedure for their deoxygenative cross-electrophile coupling with hydrosilanes, furnishing organosilane products in good to excellent yields. Mechanistic studies provide insights into the operating pathways of this semi-paired electrolytic transformation, suggesting that silyl ethers are likely reaction intermediates. Furthermore, a unified mechanistic proposal is presented that accounts for observed reactivity differences with analogous deoxygenative electrocarboxylation.

Alcohols are highly common organic compounds but remain scarce as alkyl donors in synthetic procedures. Here, we describe an electrochemical procedure for their deoxygenative cross-electrophile coupling with hydrosilanes, furnishing organosilane products in good to excellent yields. Mechanistic studies provide insights into the operating pathways of this semi-paired electrolytic transformation, suggesting that silyl ethers are likely reaction intermediates. Furthermore, a unified mechanistic proposal is presented that accounts for observed reactivity differences compared to analogous deoxygenative electrocarboxylation.

Electrochemical conversion of glycerol offers a promising route to synthesize value-added glycerol oxidation products (GOPs) from an abundant biomass-based resource. While noble metals provide a low overpotential for the glycerol electrooxidation reaction (GEOR) and high selectivity toward three-carbon (C3) GOPs, their efficiency and cost can be improved by incorporating non-noble metals. Here, we introduce an effective strategy to enhance the performance of Pd nanoparticles for the GEOR by alloying them with Ni. The resulting PdNi nanoparticles show a significant increase in both specific activity (by almost 60%) and mass activity (by almost 35%) during the GEOR at 40 °C. Additionally, they exhibit higher resistance to deactivation compared to pure Pd. Analysis of the GOPs reveals that the addition of Ni into Pd does not compromise the selectivity, with glycerate remaining at around 60% of the product fraction and the other major product being lactate at around 30%. Density functional theory calculations confirm the reaction pathways and the basis for the higher activity of PdNi. This study demonstrates a significant increase in the GEOR catalytic performance while maintaining the selectivity for C3 GOPs, using a more cost-effective nanocatalyst.

Electron spinning polarization has now attracted extensive attention due to its significant effect on improving catalysis. However, only a few photocatalysts possess the electron spinning modification property. How to endow nonmagnetic semiconductors with spintronic properties to realize spinning-regulated photocatalysis enhancement is a great challenge. Herein, based on the diluted magnetic semiconductor concept, we proposed a novel strategy to endow photocatalysts a spinning tunable property. In this work, a diluted magnetic semiconductor photocatalyst with spin polarization was constructed by only doping magnetic ions into CdS/MoS2. The spin polarization with a higher ferromagnetic property was detected in CdS and MoS2 of the Ni-doped CdS/MoS2 diluted magnetic semiconductor photocatalyst. The magnetic field-derived spin polarization reduced the charge recombination in CdS, and improved the interface transfer efficiency between CdS and MoS2, which resulted in a 3.89-fold improvement of the photocatalytic hydrogen production under an external magnetic field. This work provides a new strategy to endow nonmagnetic semiconductors with spin-regulated photocatalytic performance by constructing diluted magnetic semiconductor photocatalysts.

Glycerol is a renewable chemical that has become widely available and inexpensive owing to the increased production of biodiesel. Noble metal materials are effective catalysts for the production of hydrogen and value-added products through the electrooxidation of glycerol. In this study, we developed three platinum systems with distinct pore mesostructures, e.g., hierarchical pores (HP), cubic pores (CP) and linear pores (LP), all with high electrochemically active surface area (ECSA). The ECSA-normalized GEOR catalytic activity of the systems follows HPC > LPC > CPC > commercial Pt/C. Regarding the oxidation products, we observe glyceric acid as the main three-carbon product (C3), with oxalic acids as the main two-carbon oxidation product. DFT-based theoretical calculations support the glyceraldehyde route going through tartronic acid towards oxalic acid and also help in understanding why the dihydroxyacetone (DHA) route is active despite the absence of DHA amongst the observed oxidation products.

Pd octahedral, rhombic dodecahedral, and cubic nanoparticles (PdOCTA, PdRD, and PdCUBE NPs) were synthesized, characterized, and studied as catalysts for the glycerol electrooxidation reaction (GEOR) in a strongly alkaline medium at 20 and 60 °C. The highest mass activity of 0.050 and 0.183 mA/μgPd was observed on PdOCTA at 20 and 60 °C, respectively, whereas PdCUBE exhibited the highest specific activity of 1.49 and 12.84 mA/cmPd2, respectively. The GEOR products were analyzed by high-performance liquid chromatography (HPLC), and their selectivity and overall glycerol conversion were evaluated at 0.86 V vs RHE. The selectivity toward the three-carbon chain (C3) GEOR products was similar for the different types of catalysts, with PdOCTA and PdCUBE NPs achieving more than 50% selectivity at 20 °C and more than 60% at 60 °C. Glycerate was the overall dominant product for all catalysts, with a selectivity of up to 42%. The glycerol conversion was found to be highest for PdOCTA─21% at 20 °C and 82% at 60 °C, while PdRD was the least active and showed less than 3% conversion at 20 °C and 35% at 60 °C. Based on the GEOR product distribution, a reaction mechanism was proposed.

Glycerol, a by-product of biodiesel refineries, has uses in industries such as cosmetics, food, and pharmaceuticals. However, its usage is small compared to the amount of glycerol produced from biodiesel production. Therefore, there is an opportunity to use glycerol, an important platform chemical, as a cheap feedstock for the synthesis of valuable chemicals. These chemicals can be formed in aqueous media through the glycerol electrooxidation reaction (GEOR) on the anode with hydrogen gas concurrently generated on the cathode. This thesis focuses on the GEOR in alkaline media on Pd and PdNi catalysts. 

The works compiled here evaluate the GEOR using electrochemical methods such as cyclic voltammetry, galvanostatic polarisation curves, chronoamperometry and chronopotentiometry. Pd and PdNi catalysts were fabricated through chemical synthesis, and electrodeposition onto Ni substrates. Singularly oriented Pd crystal facets were studied, showing those approximating Pd (111) as the most active. Similarly faceted bimetallic PdNi nanoparticles proved significantly more active than pure Pd. Effects of mass transport, studied for Pd/Ni_RDE and PdNi/Ni_RDE, indicated performance effects linked to diffusion and underutilisation of thicker catalyst layers. In aerated solutions, industrially relevant current densities were achieved on PdNi/Ni_foam in concentrated electrolytes at elevated temperatures for extended periods. The analysis of glycerol oxidation products, formed during steady state measurements, was done using high performance liquid chromatography. The two major products were consistently shown to be glycerate and lactate. This work, covering many aspects of the GEOR, shows that Pd-based catalysts have potential for future industrial application.

Glycerol, en biprodukt från biodieselraffinaderier, har användningsområden i industrier som producerar kosmetika, livsmedel och läkemedel. Dess användning är dock liten jämfört med mängden glycerol som produceras från biodieselproduktion. Därför finns det en möjlighet att använda glycerol, en viktig plattformskemikalie, som ett billigt råmaterial för syntes av värdefulla kemikalier. Dessa kemikalier kan bildas i vattenlösning genom glycerolelektrooxidationsreaktionen (GEOR) på anoden samtidigt vätgas genereras på katoden. Denna avhandling fokuserar på GEOR på Pd- och PdNi-katalysatorer i alkaliska medier.

Detta arbete inkluderar studier av GEOR med hjälp av elektrokemiska metoder som cyklisk voltammetri, galvanostatiska polarisationskurvor, kronoamperometri och kronopotentiometri. Pd- och PdNi-katalysatorer tillverkades genom kemisk syntes och elektrodeposition på Ni-substrat. Singulärt orienterade Pd-kristallfacetter studerades och visade att de som närmar sig Pd (111) var de mest aktiva. Bimetalliska PdNi-nanopartiklar med liknande fasetter visade sig vara betydligt mer aktiva än ren Pd. Effekter av masstransport, som studerades för Pd/NiRDE och PdNi/NiRDE, indikerade prestandaeffekter kopplade till diffusion och underutnyttjande av tjockare katalysatorskikt. I luftade lösningar uppnåddes industriellt relevanta strömtätheter på PdNi/Nifoam i koncentrerade elektrolyter vid förhöjda temperaturer under längre perioder. Analysen av glyceroloxidationsprodukter, bildade vid stationära mätningat, gjordes med hjälp av högupplösande vätskekromatografi. De två huvudprodukterna visades konsekvent vara glycerat och laktat. Detta arbete, som täcker många aspekter av GEOR, visar att Pd-baserade katalysatorer har potential för framtida industriell tillämpning. 

Through glycerol electrooxidation, we demonstrate the viability of using a PdNi catalyst electrodeposited on Ni foam to facilitate industrially relevant rates of hydrogen generation while concurrently providing valuable organic chemicals as glycerol oxidation products. This electrocatalyst, in a solution of 2 M NaOH and 1 M glycerol at 80 °C, enabled current densities above 2000 mA cm⁻² (in a voltammetric sweep) to be obtained in atmospheres of both air and N₂. Repeated potential cycling under an aerated atmosphere to these exceptional current densities indicated a high stability of the catalyst. Through steady state polarisation curves, 1000 mA cm⁻² was reached below an anodic potential of 0.8 V vs RHE. Chronoamperometry showed glycerate and lactate being the major oxidation products, with increased selectivity for lactate at the expense of glycerate in aerated systems. Aerated atmospheres were demonstrated to consistently increase the apparent Faradaic efficiency to >100%, as determined by the concentration of oxidation products in solution. The excellent performance of PdNi/Ni in aerated solutions suggests that O₂ removal from the electrolyte is not needed for an industrial glycerol electrooxidation process, and that combining electrochemical and chemical glycerol oxidation, in the presence of dissolved O₂, presents an important process advantage.

The development of alcohol-based electrolysis to enable the concurrent production of hydrogen with low electricity consumption still faces major challenges in terms of the maximum anodic current density achievable. Whilst noble metals enable a low electrode potential to facilitate alcohol oxidation, the deactivation of the catalyst at higher potentials makes it difficult for the obtained anodic current density to compete with water electrolysis. In this work the effect of significant parameters such as mass transport, glycerol and OH- concentration and electrolyte temperature on the glycerol electrooxidation reaction (GEOR) in alkaline conditions on a bimetallic catalyst PdNi/Ni-RDE (Pd0.9Ni0.1) has been studied to discern experimental conditions which maximise achievable anodic current density before deactivation occurs. The ratio of NaOH:glycerol in the electrolyte highly affects the rate of the GEOR. A maximum current density of 793 mA cm(-2) at-0.125 V vs. Hg/HgO through steady state polarisation curves was achieved at a moderate and intermediate rotation rate of 500 RPM in a 2 M NaOH and 1 M glycerol (ratio of 2) electrolyte at 80 & DEG;C. Shown here is a method of catalyst reactivation for enabling the longterm use of the PdNi/Ni-RDE for electrolysis at optimal conditions for extended periods of time (3 h at 300 mA cm(-2) and 10 h at 100 mA cm(-2)). Through scanning electron microscopy (SEM), X-ray photon electron spectroscopy (XPS) and X-ray diffraction (XRD) it is shown that the electrodeposition of Pd and Ni forms an alloy and that after 10 h of electrolysis the catalyst has chemical and structural stability. This study provides details on parameters significant to the maximising of the GEOR current density and the minimising of the debilitating effect that deactivation has on noble metal based electrocatalysts for the GEOR.

Glycerol electrolysis affords a green and energetically favorable route for the production of value-added chemicals at the anode and H2 production in parallel at the cathode. Here, a facile method for trapping Pt nanoparticles at oxygen vacancies of molybdenum oxide (MoOx) nanosheets, yielding a high-performance MoOx/Pt composite electrocatalyst for both the glycerol oxidation reaction (GOR) and the hydrogen evolution reaction (HER) in alkaline electrolytes, is reported. Combined electrochemical experiments and theoretical calculations reveal the important role of MoOx nanosheets for the adsorption of glycerol molecules in GOR and the dissociation of water molecules in HER, as well as the strong electronic interaction with Pt. The MoOx/Pt composite thus significantly enhances the specific mass activity of Pt and the kinetics for both reactions. With MoOx/Pt electrodes serving as both cathode and anode, two-electrode glycerol electrolysis is achieved at a cell voltage of 0.70 V to reach a current density of 10 mA cm−2, which is 0.90 V less than that required for water electrolysis.