Distribution Of Oxidation Products Research Articles

Effects of Crystallinity and Branched Chain on Thermal Degradation of Polyethylene: A SCC-DFTB Molecular Dynamics Study.

As a widely used plastic, the aging and degradation of polyethylene (PE) are inevitable problems, whether the goal is to prolong the life of PE products or address the issue of white pollution. Molecular simulation is a vital scientific tool in elucidating the mechanisms and processes of chemical reactions. To obtain the distribution and evolution process of PE's thermal oxidation products, this work employs the self-consistent charge-density functional tight binding (SCC-DFTB) method to perform molecular simulations of the thermal oxidation of PE with different crystallinity and branched structures. We discovered that crystallinity does not affect the thermal oxidation mechanism of PE, but higher crystallinity makes PE more susceptible to cross-linking and carbon chain growth, reducing the degree of PE carbon chain breakage. The branched structure of PE results in differences in free volumes between the carbon chains, with larger pores leading to a concentrated distribution of O2 and chemical defects subsequently formed. The breakdown of PE is slowed down when chemical defects are localized in low-density regions of the carbon chain. The specifics and mechanism of PE's thermal oxidation are clearly revealed in this paper, which is essential for understanding the process in depth and for the development of anti-aging PE products.

Ligand‐Tailored Divergence of Copper‐Catalyzed Aerobic Oxidation of Cyclopropanols. Application to the Practical Synthesis of β‐Aminoketones and β‐Enaminones

AbstractThe aerobic ring‐opening oxidation of cyclopropanols catalyzed by copper complexes was systematically investigated, with a focus on the effect of nitrogen ligands on the distribution of oxidation products. This study led to the development of a new synthesis of β‐aminoketones and β‐enaminones from cyclopropanols, where product specificity is tuned through ligand and solvent selection. β‐Aminoketones were prepared in 34–99% yields by copper(II) acetate‐catalyzed aerobic oxidation of cyclopropanols in the presence of nucleophilic secondary aliphatic amines. In contrast, bipyridine‐ligated copper catalysts resulted in the generation of β‐enaminones in 36–86% yields, presumably via the Kornblum‐DeLaMare rearrangement of intermediate 1,2‐dioxolanes.

Secondary Organic Aerosol from OH-Initiated Oxidation of Mixtures of d-Limonene and β-Myrcene.

The chemical composition and physical properties of secondary organic aerosol (SOA) generated through OH-initiated oxidation of mixtures containing β-myrcene, an acyclic monoterpene, and d-limonene, a cyclic monoterpene, were investigated to assess the extent of the chemical interactions between their oxidation products. The SOA samples were prepared in an environmental smog chamber, and their composition was analyzed offline using ultraperformance liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry (UPLC-ESI-HRMS). Our results suggested that SOA containing β-myrcene showed a higher proportion of oligomeric compounds with low volatility compared to that of SOA from d-limonene. The formula distribution and signal intensities of the mixed SOA could be accurately predicted by a linear combination of the mass spectra of the SOA from individual precursors. Effects of cross-reactions were observed in the distribution of isomeric oxidation products within the mixed SOA, as made evident by chromatographic analysis. On the whole, β-myrcene and d-limonene appear to undergo oxidation by OH largely independently from each other, with only subtle effects from cross-reactions influencing the yields of specific oxidation products.

Paired photoelectrochemical conversion of CO2/H2O and glycerol at high rate

Photoelectrochemistry holds the promise of directly converting sunlight to valuable chemical products. Photoelectrochemical (PEC) methods, however, lag behind their electrochemical counterparts in terms of current density. In this work, we demonstrate that, by using concentrated sunlight, we can achieve current densities similar to electrochemical methods, but with lower energy input. Specifically, we combined the direct PEC oxidation of glycerol with the dark hydrogen evolution or CO2 reduction in a membrane-separated continuous-flow PEC cell. We achieved over 110 mA cm−2 photocurrent density, which is at least an order of magnitude larger than those typically reported in the literature. We demonstrated that the product distribution of glycerol oxidation is notably different in PEC and electrochemical scenarios at the same current density, and the parasitic oxygen evolution reaction can be suppressed in the PEC case. This approach raises opportunities to drive complex electrochemical reactions in a more selective manner.

Upcycle polyethylene terephthalate waste by photoreforming: Bifunction of Pt cocatalyst

Upcycle polyethylene terephthalate (PET) waste by photoreforming (PR) is a sustainable and green approach to tackle environmental problems but with challenges to obtain valuable oxidation products and high purity hydrogen simultaneously. Noble metal cocatalysts are essential to enhance the overall PR reaction efficacy. In this work, TiO2 nanotubes (TiO2 NTs) decorated with single Pt atoms (Pt1/TiO2) or Pt nanoparticles (PtNPs/TiO2) are used in the photoreforming reaction (in one batch), and the oxidation products from ethylene glycol (EG, hydrolysed product of PET) in liquid phase and hydrogen are detected. With Pt1/TiO2, EG is oxidized to glyoxal, glyoxylate or lactate, and hydrogen evolution rate (r H2) reaches 51.8 μmol⋅h−1⋅gcat−1, that is 30 times higher than that of TiO2. For PtNPs/TiO2 (size of Pt NPs: 1.97 nm), hydrogen evolution reaches 219.1 μmol⋅h−1⋅gcat−1, but with the oxidation product of acetate only. DFT calculation demonstrates that for Pt NPs, the reaction path for hydrogen evolution is preferred thermodynamically, due to the formation of Schottky junction. On the oxidation of EG, theoretical and spectroscopic analysis suggest that bidentate adsorption of EG at the interface is facile on Pt1/TiO2, compared to that on PtNPs/TiO2 (two Pt sites), but oxidation products, adsorb less strongly, compared to PtNPs/TiO2, that eventually regulates the distribution of oxidation products. The results thus demonstrate the bifunctions of Pt in the PR reaction, i.e., electron transfer mediator for hydrogen evolution and reactive sites for molecules adsorption. The oxidation reaction is dominated by the adsorption-desorption behavior of molecules but the reduction reaction is controlled by the electron transfer. In addition, acidification of pretreated PET alkaline solution achieves separation of pure terephthalic acid (PTA), which further improves the reaction efficiency possibly by offering high density of active sites and acidic environment. Our work thus demonstrates that to upcycle PET plastics, an optimized process can be reached by atomic design of photocatalysts and proper treatment on the plastic wastes.

Decomposition mechanism of Cl-VOCs on Cu- and Fe-modified activated carbon in an O2-free atmosphere: The oxidation pathway and product distribution

Activated carbon exhibits a high adsorption capacity for chlorinated volatile organic compounds (Cl-VOCs), while the desorption of Cl-VOCs is not desirable in the thermal regeneration progress of activated carbon. Chlorobenzene was selected as the model substance to explore whether Cl-VOCs can be oxidized as expected in the regeneration atmosphere of O2-free at the temperature range of 150–450 °C. The modification of activated carbon by Cu or Fe has been shown to considerably improve the decomposition activities. According to the breakthrough curves and detection results from XPS and in situ DRIFTS, the decomposition mechanism of C6H5Cl on Cu and Fe active sites is illustrated. The adsorbed C6H5Cl is firstly dechlorinated to form C6H6 and *Cl, and then it was found there are two pathways for the C6H6 oxidation. C6H6 is indirectly oxidized to form C6H5OH and benzoquinone species, or directly ring-opened to generate ethylene and 1,3-butadiene, and further oxidized to produce CO2, CO and H2O. The C6H6 oxidation is determined by the decomposition of acetate on Cu/AC, but the decomposition of benzoquinone and maleate on Fe/AC. The Fe3O4 and Fe2O3 active sites have a higher dechlorination activity but accelerate the deposition of FeCl2, FeCl3 and organic Cl-containing components. The CuO active center has a higher oxidation performance with a higher CO2 selectivity. About 83.0–83.5% of adsorbed chlorobenzene has been oxidized, and the main Cl-containing product is HCl accounting for approximately 77.8–81.0%, a small amount of Cl forms polychlorinated organic compounds or metal chlorides occupying 2.0–5.7%. As the regeneration temperature decreases, the total amount of Cl-containing species is reduced due the lower oxidation and dechlorination activity of catalysts. The decomposition products of Cl-VOCs in the thermal regeneration process of activated carbon were clarified and quantified, which provides a theoretical basis to control Cl-VOCs in regeneration gas.

Isoprene peroxy chemistry operates competitively in areas of East China

We validated the recently updated Caltech Isoprene Mechanism (CIM), which represents the complex dynamics of isoprene peroxy isomers through repetitive O2 addition and dissociation reactions, using a dataset synthesized from two field measurements taken place in both urban and rural areas of East China. The dataset covers a large span of nitric oxide (NO) levels ranging from tens of ppt characteristic of clean rural air to tens of ppb typically found in the polluted urban environment. An observationally constrained zero-dimensional box model that incorporates the CIM mechanism was constructed to simulate the daytime profiles of methacrolein (MACR) and methyl vinyl ketone (MVK), two major first-generation products that account for over half of the total carbon oxidation flow of isoprene. A closer agreement with the measurements was found compared with the traditional mechanism that prescribes a fixed yield of MACR and MVK across all NO levels. This result demonstrates that the isoprene peroxy dynamics operate competitively in the area and play a governing role in the final distribution of isoprene oxidation products. The atmospheric implication is that, with effective measures taken to reduce pollutant emissions in East China, the prevailing chemical regime at play has evolved and implementing the updated isoprene mechanism into regional models will have a profound impact on the predicted radical cycling and ozone production of the local atmosphere.

Unravelling the impacts of sulfur dioxide on dioxin catalytic decomposition on V2O5/AC catalysts

Dioxins are high chlorine, toxic, and persistent organic pollutants that exert significant pressure on both human and the environment. From the analysis of current pollutant removal of the whole life cycle, such as integrated removal of NOx, SO2 and dioxins in a system, the dioxins oxidation activity as well as the distribution of oxidation products in the presence of SO2 are still a challenge. In this study, dibenzofuran (DBF) was regarded as a model dioxin compound, and V2O5/AC was used as a catalyst to investigate the impact of SO2 on degradation activity and the degradation path of DBF. Various characterization results showed that SO2 could promote the transformation of DBF to intermediates through a reaction with lattice oxygen and lower the apparent activated energy of DBF catalytic oxidation on V2O5/AC catalysts. The density functional theory (DFT) calculations confirmed that SO2 improved the oxidation ability of lattice oxygen on V2O5/AC. The ethyl hydrogen fumarate intermediate decreased and the small-molecule byproducts increased, providing further evidence that SO2 accelerates the degradation of DBF and its intermediates. However, the formation of VOSO4 would inevitably deteriorate the adsorption and oxidation abilities of V2O5/AC. A model is pioneered to describe the relationship between SO2 promotion and VOSO4 inhibition on DBF catalytic oxidation on a V2O5/AC catalyst. This study is expected to provide theoretical guidance for the collaborative abatement of multi-pollutants in flue gas.

Solvent-free oxidation of p-tert-butyl toluene catalyzed with cobalt 4-tert-butylbenzoate in an internal circulation bubbling bed reactor

P-tert-butyl benzoic acid (PTBA) was synthesized by solvent-free oxidation of p-tert-butyl toluene (PTBT) at atmospheric pressure using cobalt 4-tert-butylbenzoate as catalyst and oxygen as an oxidant in a self-made internal circulation bubbling bed reactor (ICBBR). The effects of different catalysts and reactors on the reaction were investigated. The results show that the catalytic performance of cobalt 4-tert-butylbenzoate is superior, and the performance of the ICBBR is distinctly better than that of the batch stirred tank reactor (BSTR). The effects of reaction conditions such as flow rate, reaction temperature, and catalyst concentration on the oxidation of PTBT were studied. According to the distribution and kinetics of oxidation products, the oxidation mechanism of PTBT was analyzed. The results show that under the conditions of the oxygen flow rate of 2.5 L/min, reaction temperature of 150 °C and Co mass fraction of 250 ppm, the conversion rate of PTBT is 45.63% and the selectivity of PTBA is 97.8% after 4 h reaction without solvent. The reaction kinetics model of oxidation of PTBT to PTBA was established, and the reaction kinetics equation was obtained. The experimental values were close to the predicted values of the model.

Structural evolution characteristics of lignite during pyrolysis based on alkaline-oxygen oxidation, NMR and FTIR

Pyrolysis is a crucial conversion process for lignite to improve its quality and produce chemicals. Here, the evolution characteristics and pathways of lignite during pyrolysis were investigated by the combination of oxidation product distribution and physical structural parameters, which reflected the correlations between the size of aromatic clusters and pyrolysis temperature. The results showed that with increasing the pyrolysis temperature up to 500 ℃, the aromatic structures were enriched, and the average size of aromatic clusters increased with pyrolysis temperature. A little variation of interlayer spacing (d002) was observed, while the stacking height (Lc) and the average lateral size (La) increased gradually. Before 400 ℃, double-aromatic clusters were dominant in chars, and the corresponding chars were abundant with precursor structures of the alkaline-oxygen oxidation products benzene tricarboxylic acid (BCA3), benzene tetracarboxylic acid (BCA4) and benzene pentacarboxylic acid (BCA5). Above 400 ℃, more triple- or quadruple-ring aromatic clusters were present, and the precursor structures of benzene dicarboxylic acid (BCA2), benzene tricarboxylic acid (BCA3), and benzene tetracarboxylic acid (BCA4) increased considerably. The results indicate that the benzene carboxylic acids (BCAs) from oxidation are an effective evaluation method to reflect the abundance of aromatic rings in the parent structure of coals.

Smog Chamber Study on the Role of NOxin SOA and O3Formation from Aromatic Hydrocarbons

China is facing dual pressures to reduce both PM2.5 and O3 pollution, the crucial precursors of which are NOx and VOCs. In our study, the role of NOx in both secondary organic aerosol (SOA, the important constituent of PM2.5) and O3 formation was examined in our 30 m3 indoor smog chamber. As revealed in the present study, the NOx level can obviously affect the OH concentration and volatility distribution of gas-phase oxidation products and thus O3 and SOA formation. Reducing the NOx concentration to the NOx-sensitive regime can inhibit O3 formation (by 42%), resulting in the reduction of oxidation capacity, which suppresses the SOA formation (by 45%) by inhibiting the formation of O- and N-containing gas-phase oxidation products with low volatility. The contribution of these oxidation products to the formation of SOA was also estimated, and the results could substantially support the trend of SOA yield with NOx at different VOC levels. The atmospheric implications of NOx in the coordinated control of PM2.5 and O3 are also discussed.

The influence of storage conditions on the chemistry and flavor of hoppy ales

Understanding the factors which lead to the (in)stability of the chemistry and sensory of hoppy beer styles such as India Pale Ales (IPAs) has become a major concern for many brewers. Therefore, the evolution of several volatiles under different storage conditions (room temperature, cold storage, forced aging) was investigated in eleven hoppy ales and one lager which were commercially produced in Germany. Compared to the lager, the fresh ales contained higher initial aldehyde levels. Furthermore, the distribution of lipid oxidation and Maillard reaction products differed from those typically found in lager beer. Upon storage, significant increases of some staling aldehydes were observed. Interestingly, the concentrations of some hop aroma volatiles like terpenoids (i.e. linalool and geraniol) were relatively stable throughout storage and counteracted “oxidized” impressions in ales high in these compounds. In comparison, hop aroma in some ales was driven by less stable volatiles such as esters.

Persulfate activation by nanodiamond-derived carbon onions: Effect of phase transformation of the inner diamond core on reaction kinetics and mechanisms

To investigate the impact of carbon phase conversion on the catalytic activity of nanodiamonds, in this study, we tested nanodiamonds subjected to graphitization at varying temperatures for persulfate activation. Temperatures beyond 1000°C (where only surface graphitization occurs) steadily enhanced the persulfate activation capability as the inner carbon underwent substantial sp3-to-sp2 transformation. Nanodiamonds annealed at 2000°C outperformed benchmark nanocarbons in terms of persulfate activation efficiency. Non-radical activation occurred primarily based on the effects of radical quenchers, oxidation product distribution, substrate-dependent reactivity, and electron paramagnetic resonance spectra. Aligned with the density functional theory calculations of the binding energies of peroxydisulfate on the slab models, built via Bernal stacking of graphitic carbon layers on the diamond plane, isothermal titration calorimetry measurements suggested that the binding affinity of peroxydisulfate decreased as the sp2/sp3 ratio increased. Therefore, the enhancing effect of graphitization arose from the electrical conductivity of nanodiamonds, which increased proportionally with graphitization extent.

Low molecular weight dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls as ozonolysis products of isoprene: Implication for the gaseous-phase formation of secondary organic aerosols

Oxidation of isoprene, a major biogenic volatile organic compound emitted from forest canopies, is a potential source of oxalic acid; the dominant species in organic aerosols. We evaluated here ozonolysis of isoprene in dry darkness as a source of oxalic (C2), malonic (C3) and succinic (C4) acids. We found that oxalic acid and methylglyoxal are dominant products within 10 min of reaction followed by glyoxylic, malonic or succinic acids. Interestingly, molecular distributions of oxidation products from early reactions (9–29 min) were characterized by the predominance of methylglyoxal followed by C2, which became dominant after 30 min. The isoprene-derived secondary organic aerosols (SOAs) showed chemical evolution with reaction time towards the molecular characteristics of dicarboxylic acids similar to those of ambient aerosols (C2>C3≥C4). The carbon-based relative abundances of methylglyoxal decreased steadily (40%→30%), while those of C2 increased with reaction time (15%→25%), but no such variations persisted for glyoxal (6–10%). This finding means that methylglyoxal is more important intermediate of oxalic acid than glyoxal. In contrast, smaller variability and lower concentrations of pyruvic and glyoxylic acids than other intermediates indicate that oxalic acid formation under dry conditions follows a different pathway than in aqueous-phase heterogeneous chemistry usually invoked for cloud/fog/atmospheric waters. Here, we propose new reaction schemes for high levels of methylglyoxal and oxalic acid via gas-phase chemical reactions with ozone and OH radicals to better interpret the ambient SOA composition. Furthermore, the relative abundances of C2 exhibit small variability from 1 to 8 h, suggesting its stable character towards the oxidation by hydroxyl radicals.

Mellitic acid production by ruthenium ion-catalyzed oxidation of cokes

Cokes are rich in highly condensed aromatic rings, however, the current applications of cokes mainly focus on the thermal energy or carbon-rich structures, and the aromatic ring structures in cokes are underutilized, which are usually employed as feedstock to fabricate valuable fine chemicals and synthesized with complex steps. The pyrolysis temperatures have great impact on the structures of resulting cokes. It is necessary to learn about the structural features of cokes produced from different pyrolysis conditions to explore the optimal reaction conditions. This study reported an eco-friendly and efficient method, ruthenium ion-catalyzed oxidation, to utilize Guizhou cokes produced from different pyrolysis temperatures for green and value-added chemical production. The results indicate that arenecarboxylic acids account for more than 90% of all the oxidation products, in which mellitic acid could be up to more than 70%. Compared with previous studies, this is the highest mellitic acid yield achieved in the oxidation products of fossil resources, indicating that cokes show good performance for the clean production of mellitic acid. The ruthenium ion-catalyzed oxidation product distribution demonstrates that 1,200 °C is a turning point during coking of Guizhou coals and the structure and reactivity of Guizhou coke1,200 deviate from the expected variation tendency, which is related to the inverse influence of pyrolysis temperatures on condensation degree and ash property of cokes. Effect of pyrolysis temperatures on aromatic structures and reactivity of Guizhou cokes was also discussed further.

Enhanced Thermal Oxidation Stability of Jet Fuel by Deoxygenation Treatment

Thermal oxidation stability is an important parameter for jet fuel practical application. In this work, in order to evaluate the influence of deoxygenation on fuel stability, samples of typical fuels (JP-10 and RP-3) were subjected to deoxygenation by nitrogen purge and then subjected to accelerated thermal oxidation (180°C, 200°C, and 220°C). The parameters of hydroperoxide number, total acid number, size distribution of insoluble oxidation products, and concentration of remaining antioxidant (butylated hydroxytoluene, MIT) were monitored and analyzed. The results show that deoxygenation and thermal oxidation have very little influence on the fuel physical properties (density, net heating value, and kinematic viscosity). However, deoxygenation significantly reduces hydroperoxide number, total acid number, and remaining BHT concentration in the fuel after accelerated oxidation. Moreover, the deoxygenation treatment also inhibits the formation of soluble macromolecular oxidatively reactive species (SMORS) and insoluble oxidation products such as gums and deposits.

Ispitivanje procesa oksidacije Bi2S3 na povišenim temperaturama u atmosferi vazduha

Bismuth (III) sulfide has been widely researched in recent years due to its application, but little emphasis has been placed on research regarding its behavior at elevated temperatures. This is of great importance, considering that bismuth, in the form of Bi2S3, is found in copper sulfide concentrates and is considered one of the most harmful components, along with lead, arsenic and antimony. The removal of these substances is one of the basic tasks in the processes of pyrometallurgical extraction of copper, in order to obtain a high purity metal. In order to better understand the behavior of bismuth (III) sulfide during oxidation at elevated temperatures, this paper characterized the synthesized sample of Bi2S3 at room temperature and the oxidation products at 500 °C by X-Ray diffraction (XRD), as well as thermodynamic, thermal and kinetic analysis of the oxidation process of Bi2S3 at elevated temperatures. In order to understand the behavior of Bi2S3 during oxidation and the distribution of oxidation products, phase stability diagrams in the Bi-S-O system were constructed at different temperatures and the values of the Gibbs free energy change at 400 °C and 1000 °C were calculated. Kinetic analysis of Bi2S3 oxidation process was performed by Kissingers method in non-isothermal conditions.

Electrochemical treatment of industrial sulfidic spent caustic streams for sulfide removal and caustic recovery

Alkaline spent caustic streams (SCS) produced in the petrochemical and chemical manufacturing industry, contain high concentrations of reactive sulfide (HS−) and caustic soda (NaOH). Common treatment methods entail high operational costs while not recovering the possible resources that SCS contain. Here we studied the electrochemical treatment of SCS from a chemical manufacturing industry in an electrolysis cell, aiming at anodic HS− removal and cathodic NaOH, devoid of sulfide, recovery. Using a synthetic SCS we first evaluated the HS− oxidation product distribution over time, as well as the HS− removal and the NaOH recovery, as a function of current density. In a second step, we investigated the operational aspects of such treatment for the industrial SCS, under 300 A m−2 fixed current density. In an electrolysis cell receiving 205 ± 60 g S L−1 d−1 HS− over 20 days of continuous operation, HS− was removed with a 38.0 ± 7.7 % removal and ∼80 % coulombic efficiency, with a concomitant recovery of a ∼12 wt.% NaOH solution. The low cell voltage obtained (1.75 ± 0.12 V), resulted in low energy requirements of 3.7 ± 0.6 kW h kg−1 S and 6.3 ± 0.4 kW h kg−1 NaOH and suggests techno-economic viability of this process.

Micro-structural evolution of oxide scales formed on a Nb-Stabilizing heat-resistant steel at the initial stage in high-temperature water vapor

Early oxidation behavior of a Nb-Stabilizing heat-resistant steel in water vapor at 700 °C for 336 h was investigated. Micro-characterization methods including in-depth XPS, SEM/EDS, FIB were employed to acquire the composition and distribution of oxidation products. The results showed that the oxidation kinetics of this heat-resistant steel almost followed a parabolic law at 700 °C, indicating the oxidation was controlled by the ion diffusion. Surfaces of oxidation products on TP347HFG were gradually from compact to loose with a longer exposure. Oxide scales were mainly composed of layered (Mn, Fe)Cr2O4 and Cr2O3 and scattered Nb2O5. Contents of Mn at the surface were much higher than other positions, confirming that Mn diffuse much faster than Fe and Cr. During the initial oxidation stage, NbC was transformed into Nb2O5, which was covered by Fe–Cr oxide scales. The growth of oxide scales on TP347HFG is suggested.

Radical Redox Mediator Free Photoelectrochemical Biomass Valorization

Over the past decade, researchers have begun to re-explore the idea of replacing water oxidation with more kinetically facile oxidation reactions for photoelectrochemical solar H2 production.1–3 Alternate photo-oxidation reactions can be employed as a means of chemical valorization, in addition to providing electrons for H2 production from water while reducing the losses associated with water oxidation. In particular, the oxidation of 5-hydroxymethylfurfural (HMF)—which is a key intermediate derived from the acid catalyzed poly-dehydration of 6 carbon monosaccharides—has gained significant attention. This is because a number of its oxidation products, such as 2,5-Furandicarboxylic acid (FDCA), may be employed as monomers in the synthesis of renewable polyesters, and FDCA in particular, has also been identified by the US Department of Energy as one of 12 priority chemicals for establishing the green chemistry industry of the future.4 As a result, solar powered chemical transformations of HMF have recently gained attention. However, to date, the selective oxidation of HMF using either photo-, or electrochemical means, has been limited by the need to employ the radical redox mediator (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO). This additional redox-mediating reagent poses a problem by increasing system complexity, and by behaving as a competitive light absorber in photoelectrochemical (PEC) systems —which reduces the solar conversion efficiency. Recently, our group has investigated TEMPO free, direct PEC oxidation of HMF using metal oxide photoelectrodes. In this presentation, we show that the direct oxidation of HMF can be carried out on sol-gel processed WO3 electrodes without the need to use an additional redox shuttle such as TEMPO. Figure 1 depicts a linear sweep voltammogram under 1 sun illumination of a sol-gel processed WO3 electrode in the presence and absence of HMF. We observe that the addition of HMF to an aqueous buffered solution improves photocurrent densities by 33%, and the onset potential is favorably shifted by -50 mV. These properties highlight this reaction’s promise as a replacement for water oxidation in an H2 producing PEC cell. In addition, we report the oxidation product distribution as well as efforts to control product selectivity via solution processed heterogeneous catalysts and the optimization of the electrolyte solution. Figure 1: Linear sweep voltammograms of a WO3 electrode in a pH 4 0.1M KPi buffered solution with (red), and without (black), 5mM HMF in solution. The illumination intensity was 1 sun AM1.5G. Dotted lines represent the linear sweep voltammograms in the absence of illumination.