Hydroxyl Species Research Articles

Catalytic valorization of glycerol in the absence of external hydrogen: Effect of the Cu/ZrO2 catalyst mass and solvent

The glycerol valorization by heterogeneous catalysis to produce high-value-added chemicals is mainly carried out in the presence of high pressures of molecular hydrogen, a highly flammable gas whose main production in our days depends on fossil fuels. Therefore, an attractive alternative to explore is hydrogen in-situ generation in the catalytic process. Herein, we investigated the liquid-phase catalytic valorization of 80% wt. glycerol in different solvents such as water, 2-propanol, and acetone using a Cu/ZrO2 catalyst in the absence of external hydrogen. Firstly, the mass effect of the Cu/ZrO2 in the glycerol aqueous medium was evaluated finding an optimum mass of 250 mg for glycerol conversion. At these conditions, an initial reaction rate value of 2.63 × 10−3 molgly·gcat−1·min−1 was observed while the main products were hydroxyacetone (HA) and 1,2-propanediol (1,2-PDO). The use of 2-propanol as solvent and hydrogen donor molecule in the glycerol conversion induced the hydrogenation of hydroxyacetone towards 1,2-PDO. The ratio between the selectivity of 1,2-PDO/HA was found to be higher than that observed for the catalytic experiment with water. For the conversion of glycerol in the presence of acetone as a solvent it was noted the occurrence of acetalization reaction of glycerol with acetone and the main product observed was 4-hydroxymethyl-2,2-dimethyl-1,3-dioxalane or solketal. Density functional theory (DFT) calculations were included to gain insight into the reaction mechanisms of the hydroxyacetone hydrogenation to the formation of 1,2-PDO on Cu/ZrO2 catalyst. Four possible pathways were considered. The elementary steps include several intramolecular hydrogen atom transfer steps and two hydrogen addition steps. The hydrogen sources would come from adsorbed hydroxyl species of the aqueous reaction medium on ZrO2 support.

Selenium-Containing Type-I Organic Photosensitizers with Dual Reactive Oxygen Species of Superoxide and Hydroxyl Radicals as Switch-Hitter for Photodynamic Therapy.

Organic type-I photosensitizers (PSs) which produce aggressive reactive oxygen species (ROS) with less oxygen-dependent exhibit attractive curative effect for photodynamic therapy (PDT), as they adapt better to hypoxia microenvironment in tumors. However, the reported type-I PSs are limited and its exacted mechanism of oxygen dependence is still unclear. Herein, new selenium-containing type-I PSs of Se6and Se5with benzoselenadiazole acceptor has been designed and possessed aggregation-induced emission characteristic. Benefited from double heavy-atom-effect of selenium and bromine, Se6shows a smaller energy gap (ΔEST ) of 0.03eV and improves ROS efficiency. Interestingly, type-I radicals of both long-lived superoxide anion (O2 •‾ ) and short-lived hydroxyl (• OH) are generated from them upon irradiation. This may provide a switch-hitter of dual-radical with complementary lifetimes for PDT. More importantly, simultaneous processes to produce • OH are revealed, including disproportionation of O2 •‾ and reaction between excited PS and water. Actually, Se6displays superior in-vitro PDT performance to commercial chlorin e6 (Ce6), under normoxia or hypoxia. After intravenous injection, a significantly in-vivo PDT performance is demonstrated on Se6, where tumor growth inhibition rates of 99% is higher than Ce6. These findings offer new insights about both molecular design and mechanism study of type-I PSs.

Hyperoxidation active species produced by seawater electro membrane reactor assisted electrolytic cell system for simultaneous decyanation and carbon removal

Herein, a novel triple-layered heterojunction catalytic cathode membrane (PVDF/rGO/TFe/MnO2, TMOHccm) was reported and applied in seawater electro membrane reactor assisted electrolytic cell system (SEMR-EC), achieving increased properties for cyanide wastewater treatment. Hydrophilic TMOHccm exhibits higher electrochemical activity (qT* 1.11 C cm−2, qo* 0.03 C cm−2), indicating excellent electron transfer efficiency. Further analysis shows a one-electron redox cycle of exposed transition metal oxides (TMOs) on rGO support mediated oxygen reduction reaction (ORR) process, and calculated results of density functional theory (DFT) demonstrates positive Bader charge (72 |e|) of synthesized catalyst. The developed SEMR-EC was implemented in intermittent-stream operation for treating cyanide wastewater, the system achieved optimized decyanation and carbon removal performance (CN− 100%, TOC 88.49%). Hyperoxidation active species produced SEMR-EC including hydroxyl, sulfate, and reactive chlorine species (RCS) was confirmed. The proposed mechanistic explanation indicated multiple removal pathways relevant to cyanide, organic matter, and iron were elucidated, and the engineering applications prospects were highlighted by cost (5.61 $) and benefit (Ce 399.26 mW m−2 $−1, EFe 248.11 g kWh−1) analysis of the system.

Unconventional Bilateral Compressive Strained Ni-Ir Interface Synergistically Accelerates Alkaline Hydrogen Oxidation.

The alkaline hydrogen oxidation reaction (HOR) involves the coupling of adsorbed hydrogen (Had) and hydroxyl (OHad) species and is thus orders of magnitude slower than that in acid media. According to the Sabatier principle, developing electrocatalysts with appropriate binding energy for both intermediates is vital to accelerating the HOR though it is still challenging. Herein, we propose an unconventional bilateral compressive strained Ni-Ir interface (Ni-Ir(BCS)) as efficient synergistic HOR sites. Density functional theory (DFT) simulations reveal that the bilateral compressive strain effect leads to the appropriate adsorption for both Had and OHad, enabling their coupling thermodynamically spontaneous and kinetically preferential. Such Ni-Ir(BCS) is experimentally achieved by embedding sub-nanometer Ir clusters in graphene-loaded high-density Ni nanocrystals (Ni-Ir(BCS)/G). As predicted, it exhibits a HOR mass activity of 7.95 and 2.88 times those of commercial Ir/C and Pt/C together with much enhanced CO tolerance, respectively, ranking among the most active state-of-the-art HOR catalysts. These results provide new insights into the rational design of advanced electrocatalysts involving coordinated adsorption and activation of multiple reactants.

The Metal-Oxide Nanoparticle-Aqueous Solution Interface Studied by Liquid-Microjet Photoemission.

ConspectusThe liquid-microjet technique combined with soft X-ray photoelectron spectroscopy (PES) has become an exceptionally powerful experimental tool to investigate the electronic structure of liquid water and nonaqueous solvents and solutes, including nanoparticle (NP) suspensions, since its first implementation at the BESSY II synchrotron radiation facility 20 years ago. This Account focuses on NPs dispersed in water, offering a unique opportunity to access the solid-electrolyte interface for identifying interfacial species by their characteristic photoelectron spectral fingerprints. Generally, the applicability of PES to a solid-water interface is hampered due to the small mean free path of the photoelectrons in solution. Several approaches have been developed for the electrode-water system and will be reviewed briefly. The situation is different for the NP-water system. Our experiments imply that the transition-metal oxide (TMO) NPs used in our studies reside close enough to the solution-vacuum interface that electrons emitted from the NP-solution interface (and from the NP interior) can be detected.We were specifically exploring aqueous-phase TMO NPs that have a high potential for (photo)electrocatalytic applications, e.g., for solar fuel generation. The central question we address here is how H2O molecules interact with the respective TMO NP surface. Liquid-microjet PES experiments, performed from hematite (α-Fe2O3, iron(III) oxide) and anatase (TiO2, titanium(IV) oxide) NPs dispersed in aqueous solutions, exhibit sufficient sensitity to distinguish between free bulk-solution water molecules and those adsorbed at the NP surface. Moreover, hydroxyl species resulting from dissociative water adsorption can be identified in the photoemission spectra. An important aspect is that in the NP(aq) system the TMO surface is in contact with a true extended bulk electrolyte solution rather than with a few monolayers of water, as is the case in experiments using single-crystal samples. This has a decisive effect on the interfacial processes that can occur since NP-water interactions can be uniquely investigated as a function of pH and provides an environment allowing for unhindered proton migration. Our studies confirm that water is dissociatively adsorbed at the hematite surface and molecularly adsorbed at the TiO2 NP surface at low pH. In contrast, at near-basic pH the water interaction is dissociative at the TiO2 NP surface.The liquid-microjet measurements presented here also highlight the multiple aspects of photoemission necessary for a full characterization of TMO nanoparticle surfaces in aqueous environments. For instance, we exploit the ability to increase species-specific electron signals via resonant photoemission, so-called partial electron yield X-ray absorption (PEY-XA) spectra, and from valence photoelectron and resonant Auger-electron spectra. We also address the potential of these resonance processes and the associated ultrafast electronic relaxations for determining charge transfer or electron delocalization times, e.g., from Fe3+ located at the hematite nanoparticle interface into the aqueous-solution environment.

Sunlight-driven intimately coupled photocatalysis and biodegradation (SDICPB): A sustainable approach for enhanced detoxification of triclosan

Triclosan is considered as recalcitrant contaminant difficult to degrade from the contaminated wastewater. Thus, promising, and sustainable treatment method is necessary to remove triclosan from the wastewater. Intimately coupled photocatalysis and biodegradation (ICPB) is an emerging, low-cost, efficient, and eco-friendly method for the removal of recalcitrant pollutants. In this study BiOI photocatalyst coated bacterial biofilm developed at carbon felt for efficient degradation and mineralization of triclosan was studied. Based on the characterization of BiOI prepared using methanol had lower band gap 1.85 eV which favors lower recombination of electron-hole pair and higher charge separation which ascribed to enhanced photocatalytic activity. ICPB exhibits 89% of triclosan degradation under direct sunlight exposure. The results showed that production of reactive oxygen species hydroxyl radical and superoxide radical anion played crucial role in the degradation of triclosan into biodegradable metabolites further the bacterial communities mineralized the biodegradable metabolites into water and carbon dioxide. The confocal laser scanning electron microscope results emphasized that interior of the biocarrier shows a large number of live bacterial cells existing in the photocatalyst-coated carrier, where the little toxic effect on bacterial biofilm occurred on the exterior of the carrier. The extracellular polymeric substances characterization result remarkable confirms that which could act as sacrificial agent of photoholes further helped by preventing the toxicity to the bacterial biofilm from the reactive oxygen species and triclosan. Hence, this promising approach can be a possible alternative method for the wastewater treatment polluted with triclosan.

Dynamically Formed Active Sites on Liquid Boron Oxide for Selective Oxidative Dehydrogenation of Propane

Boron oxide-based catalysts have been shown to be both active and selective for driving the oxidative dehydrogenation of propane (ODHP) without the use of metal promoters. However, this reaction occurs at temperatures where boron oxide melts, challenging experimental identification of the molecular structures within the boron oxide phase under reaction conditions and thus hindering the understanding of its active sites and reaction mechanism(s). By combining density functional theory computations, ab initio molecular dynamics simulations, in situ Raman characterization, and microkinetic modeling, we propose that dimerized di-coordinated boron sites (>B–B<)─dynamically formed in liquid boron oxide─are the active species for O2 activation under reaction conditions. The resulting peroxy-like species (>B–O–O–B<) is then responsible for propane activation but is a moderate oxidant for ODHP and thus inert to propene. These peroxy-like structures rapidly activate propane, homolytically cleaving the >B–O–O–B< bond, producing a propyl radical and a >B–O• dangling bond. These > B–O• originate from the >B–O–O–B< sites as well as the liquid B2O3 structure itself and play a critical role in the abstraction of H atoms from propane and propyl. In fact, microkinetic modeling reveals that the formation of adsorbed C3H7* radicals is the main rate-controlling step due to the highly endergonic adsorption of propane into the system. Otherwise, the only activated processes were found to be the dehydration steps that lead to water formation, which exhibit an intriguing dependence on the concentration of surface hydroxyl species. These findings provide significant insights into the ODHP mechanisms on boron-based catalysts and emphasize the importance of understanding the liquid nature of the oxide to account for its catalytic activity.

Modulating the Interfacial Water Network of Dual-Site Pd/FeOx/C Catalyst for Efficient Formate Electrooxidation.

The rational design of electrocatalysts for formate oxidation reaction (FOR) in alkaline media is crucial to promote the practical applications of direct formate fuel cells (DFFCs). The FOR kinetic on palladium (Pd) based electrocatalysts is strongly hindered by unfavorably adsorbed hydrogen (Had) as the major intermediate species blocking the active sites. Herein, we report a strategy of modulating the interfacial water network of dual-site Pd/FeOx/C catalyst to significantly enhance the desorption kinetics of Had during FOR. Aberration-corrected electron microscopy and synchrotron characterizations revealed the successful construction of Pd/FeOx interfaces on carbon support as a dual-site electrocatalyst for FOR. Electrochemical tests and in situ Raman spectroscopy results showed that Had could be effectively removed from the active sites of the as-designed Pd/FeOx/C catalyst. CO-stripping voltammetry and density functional theory calculations (DFT) demonstrated that the introduced FeOx could effectively accelerate the dissociative adsorption of water molecules on active sites, which accordingly generates adsorbed hydroxyl species (OHad) to facilitate the removal of Had during FOR. This work provides a novel route to develop advanced FOR catalysts for fuel cell applications.

Investigation of antibacterial photodynamic inactivation in urea-doped TiO2 sensitized with porphyrin photocatalysis

Choosing the right photosensitizers (PSs) as well as the right light source is very critical in antimicrobial photodynamic therapy (aPDT). Some light sources, such as ultraviolet, have high cytotoxicity and poor penetration and some PSs are hydrophobic with low solubility in water, and easy aggregation. To address these issues, we modified TiO2 nanoparticles with urea and TCPP (TCPP=tetra(4-carboxyphenyl) porphyrin) as a PS and prepared N-doped-TiO2 (NT), TCPP/TiO2 (PT), and TCPP/N-doped-TiO2 (PNT). Urea is a safe compound used here as a source of nitrogen (N). Nitrogen doping produces a localized N state within the TiO2 bandgap which broadens the absorption in the visible light region. Both urea and TCPP shifted the bandgap of TiO2 to the visible area and enabled the photodegradation of methylene blue after 30 min of aging under visible light. 1O2 production was monitored by the rapid and irreversible conversion of anthracene to its corresponding endoperoxide. Meanwhile, different scavengers such as p-benzoquinone (p-BQ) and tert-butanol (t-BuOH) were employed in a photocatalytic process to specify the existence of superoxide and hydroxyl radical species, respectively. PNT showed a promising photobactericidal activity and reached 100% of inhibition activity against both types of bacteria after 120 and 180 min, respectively under LED lamp (15 W) irradiation. The interaction between PNT and bacteria was also examined by FESEM.

Universal Strategy for Reversing Aging and Defects in Graphene Oxide for Highly Conductive Graphene Aerogels.

The production of highly stable, defect-free, and electrically conducting 3D graphene structures from graphene oxide precursors is challenging. This is because graphene oxide is a metastable material whose structure and chemistry evolve due to aging. Aging changes the relative composition of oxygen functional groups attached to the graphene oxide and negatively impacts the fabrication and properties of reduced graphene oxide. Here, we report a universal strategy to reverse the aging of graphene oxide precursors using oxygen plasma treatment. This treatment decreases the size of graphene oxide flakes and restores negative zeta potential and suspension stability in water, enabling the fabrication of compact and mechanically stable graphene aerogels using hydrothermal synthesis. Moreover, we employ high-temperature annealing to remove oxygen-containing functionalities and repair the lattice defects in reduced graphene oxide. This method allows obtaining highly electrically conducting graphene aerogels with electrical conductivity of 390 S/m and low defect density. The role of carboxyl, hydroxyl, epoxide, and ketonic oxygen species is thoroughly investigated using X-ray photoelectron and Raman spectroscopies. Our study provides unique insight into the chemical transformations occurring during the aging and thermal reduction of graphene oxide from room temperature up to 2700 °C.

Cooperative Rh-O5/Ni(Fe) Site for Efficient Biomass Upgrading Coupled with H2 Production.

Designing efficient and durable bifunctional catalysts for 5-hydroxymethylfurfural (HMF) oxidation reaction (HMFOR) and hydrogen evolution reaction (HER) is desirable for the co-production of biomass-upgraded chemicals and sustainable hydrogen, which is limited by the competitive adsorption of hydroxyl species (OHads) and HMF molecules. Here, we report a class of Rh-O5/Ni(Fe) atomic site on nanoporous mesh-type layered double hydroxides with atomic-scale cooperative adsorption centers for highly active and stable alkaline HMFOR and HER catalysis. A low cell voltage of 1.48 V is required to achieve 100 mA cm-2 in an integrated electrolysis system along with excellent stability (>100 h). Operando infrared and X-ray absorption spectroscopic probes unveil that HMF molecules are selectively adsorbed and activated over the single-atom Rh sites and oxidized by in situ-formed electrophilic OHads species on neighboring Ni sites. Theoretical studies further demonstrate that the strong d-d orbital coupling interactions between atomic-level Rh and surrounding Ni atoms in the special Rh-O5/Ni(Fe) structure can greatly facilitate surface electronic exchange-and-transfer capabilities with the adsorbates (OHads and HMF molecules) and intermediates for efficient HMFOR and HER. We also reveal that the Fe sites in Rh-O5/Ni(Fe) structure can promote the electrocatalytic stability of the catalyst. Our findings provide new insights into catalyst design for complex reactions involving competitive adsorptions of multiple intermediates.

Conjunction of ferric ion with chloride ion facilitated zero-valent copper/air system to eliminate paracetamol: Mechanistic insights and performance evaluation

Zero-valent copper/air process was studied in degrading contaminants owing to in-site generation of hydrogen peroxide and reactive oxygen species, while its oxidation efficacy was restrained by the dismutation of cuprous ion. In this study, when the dosages of paracetamol, ferric ion, chloride ion and zero-valent copper were respectively 10 μM, 40 μM, 2 mM and 0.2 g/L at pH 3.0, the paracetamol elimination was greatly enhanced and increased from 9.2% to 76.5% within 30 min with adding both ferric ion and chloride ion in the zero-valent copper/air process. Hydroxyl radical and reactive chlorine species were identified as the dominant reactive oxygen species, and the contribution rates of hydroxyl radical and reactive chlorine species to eliminating paracetamol were respectively 68.2% and 28.9%. In the proposed system, zero-valent copper and cuprous ion expedited the ferric/ferrous circulation, conducing to the production of reactive oxygen species. Moreover, chloride ion coupled with cuprous ion producing the cuprous chloride complexes, and chloride ion contributed to the comproportionation between zero-valent copper with cupric ion to form cuprous chloride, receding the dismutation of cuprous ion and contributing to the formation of hydrogen peroxide and reactive oxygen species. When zero-valent copper reused for three times in the proposed system, the degradation of paracetamol reached 62%. After we increased the end pH to > 7.0 and leaching, the total copper of reaction solution was under 0.85 mg/L and the acute toxicity had no insignificant increase for discharge water. The study provided a new idea to enhance zero-valent copper/air system for the purification of pollutants.

Selectivity Control of Oxygen Reduction Reaction over Mesoporous Transition Metal Oxide Catalysts for Electrified Purification Technologies

Direct electrification of oxygen-associated reactions contributes to large-scale electrical storage and the launch of the green hydrogen economy. The design of the involved catalysts can mitigate the electrical energy losses and improve the control of the reaction products. We evaluate the effect of the interface composition of electrocatalysts on the efficiency and productivity of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), both mechanistically and at device levels. The ORR and OER were benchmarked on mesoporous nickel(II) oxide and nickel cobaltite (NiO and NiCo2O4, respectively) obtained by a facile template-free hydrothermal synthesis. Physicochemical characterization showed that both NiO and NiCo2O4 are mesoporous and have a cubic crystal structure with abundant surface hydroxyl species. NiCo2O4 showed higher electrocatalytic activity in OER and selectivity to water as the terminal product of ORR. On the contrary, ORR over NiO yielded hydroxyl radicals as products of a Fenton-like reaction of H2O2. The product selectivity in ORR was used to construct two electrolyzers for electrified purification of oxygen and generation of hydroxyl radicals.

Understanding reactivity of self-assembled monolayer-coated electrodes: SAM-induced surface reconstruction

Thiolate self-assembled monolayers (SAMs) are often used to modify surface properties, including catalytic activity. These SAMs can also induce reconstruction of some metallic surfaces. Here we show, through formation and subsequent removal of thiolate SAMs from Au polycrystalline electrocatalysts, that irreversible changes to the underlying metal surface can lead to significant changes in catalytic properties, irrespective of specific interactions that might occur between thiolate molecules and various reactants. Using underpotential deposition of Pb as a surface probe, we find that across a range of different thiolates, SAMs tend to increase the proportion of (111)-facets on Au, but they simultaneously increase the defect density upon these and other facets. These changes generally lead to delayed onset but higher maximum activity toward formic acid oxidation, which is hypothesized to relate to changes in both the density of appropriate active site ensembles and interactions of intermediates and site-blocking hydroxyl species with newly generated defects. The impacts of reconstruction are further illustrated through measured shifts in selectivity for electroreduction of crotonaldehyde, with reconstructed catalysts changing the favored product from butanal to crotyl alcohol. Thus, complex surface reorganization may play a significant role in the catalytic behaviors of SAM-modified surfaces.

Designing of graphene oxide-induced p-NiO/n-MoO3 heterostructures for improved photocatalytic activity through plasmon-enhanced S-scheme mechanism and its biological and electrochemical performance.

An environmentally benign, economically advantageous microwave hydrothermal approach is used in synthesis of desirably tailored graphene oxide-induced p-NiO/n-MoO3 (GNM) heterostructures. Various analytical techniques such XPS, XRD, UPS, EIS, and Mott-Schottky were conducted to comprehend complete morphology and functioning of the novel ternary heterostructure photocatalysts. Also, SEM and HR-TEM images were presented for better interpretation. The strategic plasmonic step scheme (S-scheme) charge migration approach was used to describe the effective charge recombination process. Hydroxyl and oxide active species were corollaries of the reactive radical-scavenging experiments and electron spin resonance. The work function has been confirmed using ultraviolet photoelectron spectroscopy (UPS), which assessed an electron transfer between NiO and MoO3, yielding work function values of 6.32eV and 5.26eV, respectively. The cell apoptosis of the HeLa cell line approves the material's biocompatibility. Cyclic voltammetry and electrochemical impedance spectroscopy reveal electrochemical performance of GNM heterostructures. We anticipate our results would pave the way for current and future applications. In order to ensure eco-restoration such photocatalyst which are eco and cost friendly are synthesized. Assessment of pollutant risks presents the impact of them on human and terrestrial and aquatic animals. Sustainability of material is acknowledge as they use solar light for photocatalysis and dye degradation, and hence can be green material. One such material for the treatment of wastewater, dye-infused waters, and industrial water has been tailored, which is capable of dye degradation, heavy metal, and other pollutant removal. Very importantly, the synthesized material is a biocompatible one.

Synthesis and Characterization of New Tetradentate N2O2-Based Schiff’s Base Cu (II) Complexes for Dye Photodegradation

We have reported tetradentate ligands (salophen) coordinated with N and O atoms that led to the Cu (II) complexes. These Cu (II) complexes (C-1 and C-2) were firstly established by using elemental analysis and confirmed by mass spectra. At the same time, the characterization of C-1 and C-2 complexes is performed by using several spectroscopic methods and morphological analysis. The bandgap values of the C-1 and C-2 complexes are evaluated with UV-vis DRS spectra. The PL spectral data and photocurrent curves clearly indicated the small recombination rate of the hole–electron pair. The synthesized C-1 and C-2 complexes’ photocatalytic properties were examined for the degradation of cationic dyes such as methylene blue (MB λmax.= 654 nm) and methyl violet (MV λmax.= 590 nm) below visible-light action. The C-2 complex is more active than the C-1 complex because of its high photostability, small band-gap energy, and low recombination rate for hole–electron pair separation, and improved visible-light character, which encourages the generation of hydroxyl radical species throughout the photodegradation process. Scavenger probes were used to identify the dynamic species for the photodegradation of dyes, and a mechanism investigation was established.

In Situ Construction of Ni/Ni0.2Mo0.8N Heterostructure to Enhance the Alkaline Hydrogen Oxidation Reaction by Balancing the Binding of Intermediates

AbstractThe inferior activity of hydrogen oxidation reaction (HOR) in alkali severely hampers the deployment of Ni catalysts in the promising anion exchange membrane fuel cells (AEMFCs), due to the unbalanced binding energies of hydrogen (HBE) and hydroxyl (OHBE) species. Ni‐Mo alloy and nickel nitride have been proven to improve the Ni‐based activities of HOR but they still can be further enhanced. Because it sacrifices the HBE for enlarging OHBE. Herein, it is reported that the activity can be further improved by constructing heterostructure between Ni nanoparticles (NPs) and nitride of Ni‐Mo alloy (Ni0.2Mo0.8N) by an in situ synthetic strategy. The in situ prepared reduced graphene oxide (rGO) supported heterostructure (Ni/Ni0.2Mo0.8N/rGO) possesses the state‐of‐the‐art activity (overpotential of 100 mV to achieve 2.9 mA cm−2), faster kinetics (kinetics current density of 11.20 mA cm−2 and exchange current density of 2.74 mA cm−2), and ultrahigh durability (maintaining the current densities for over 40 h or 10000 cycles). Detailed characterizations together with density functional theory simulations reveal that the tuned d‐band electronic structures optimize and balance the HBE and OHBE, facilitating the HOR process on the as‐fabricated heterostructured catalyst.

In Situ Fabrication of Silver Peroxide Hybrid Ultrathin Co-Based Metal-Organic Frameworks for Enhanced Chemodynamic Antibacterial Therapy.

Bacterial-induced infectious diseases have always caused an unavoidable problem and lead to an increasing threat to human health. Hence, there is an urgent need for effective antibacterial strategies to treat infectious diseases. Current methods are often ineffective and require large amounts of hydrogen peroxide (H2O2), with harmful effects on normal healthy tissue. Chemodynamic therapy (CDT) provides an ideal infection microenvironment (IME)-activated paradigm to tackle bacterial-related diseases. To take full advantage of the specificity of IME and enhanced CDT for wounds with bacterial infection, we have designed an intelligent antibacterial system that exploits nanocatalytic ZIF-67@Ag2O2 nanosheets. In this system, silver peroxide nanoparticles (Ag2O2 NPs) were grown on ultrathin zeolitic imidazolate framework-67 (ZIF-67) nanosheets by in situ oxidation, and then, ZIF-67@Ag2O2 nanosheets with the ability to self-generate H2O2 were triggered by the mildly acidic environment of IME. Lamellar ZIF-67 nanosheets were shown to rapidly degrade and release Co2+, allowing the conversion of less reactive H2O2 into the highly toxic reactive oxygen species hydroxyl radicals (•OH) for enhanced CDT antibacterial properties. In vivo results revealed that the ZIF-67@Ag2O2 nanosheet system exhibits excellent antibacterial performance against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The proposed hybrid strategy demonstrates a promising therapeutic strategy to enable antibacterial agents with IME-responsive nanocatalytic activity to circumvent antibiotic resistance against bacterial infections.

Synthesis of Bimetallic Metal-Organic Frameworks (MOFs) La-Y-PTC for Enhanced Dyes Photocatalytic Degradation

Metal-Organic Frameworks (MOFs) is widely utilized as photocatalysts in dye photocatalytic degradation. This study successfully synthesized bimetallic MOFs La-Y-PTC by the solvothermal method. The synthesized La-Y-PTC has a diffractogram pattern with a value of 2θ = 5.69°; 9.57°; 16.8°; 20.05°; 24.8°; 26.15°; 29.77° and 41.93° with a crystal size of 21.45 nm. The La-Y-PTC has symmetric and asymmetric (COO−) at 1591 and 1433 cm−1, La−O and Y−O groups at 596 and 659 cm−1 and a band gap energy of 2.16 eV. Scanning Electron Microscope analysis showed that the morphology of La-Y-PTC is spherical with a particle size of 354.307 nm. La-Y-PTC degrades methylene blue and methyl orange at pH 2 with a degradation efficiency of 69.57% and 93.63%, respectively, under 250 watts of mercury lamp irradiation for 180 min with hydroxyl radical species as a dominant species that play a role in methylene blue and methyl orange degradations. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Self-reduction synthesis of supported ultrafine Pd nanoparticles with high activity and stability in hydrogenation

Supported ultrafine metal nanoparticles display outstanding catalytic performance in heterogeneous catalysis. Nevertheless, there are limited convenient and practical approaches for synthesizing supported ultrafine metal nanoparticle catalysts, despite the development of advanced fabrication methods. High-temperature reduction is often required for the preparation of metal catalysts for catalytic hydrogenation. However, the use of reductants, such as H2, easily leads to the aggregation of nanoparticles during catalyst preparation. In this work, we developed an effective self-reduction strategy using Pd precursors with organic ligands to prepare supported ultrafine Pd catalysts. Simple calcination under an inert atmosphere leads to the formation of uniform and ultrafine Pd nanoparticles (∼1 nm). These Pd precursors were reduced following the reaction between the −CHx groups on ligands and surface hydroxyl species on oxide supports. CO and oxygen vacancies generated in situ both contributed to the stabilization of ultrafine Pd nanoparticles. The as-prepared ultrafine Pd nanoparticles were highly stable even after the high-temperature treatment at 600°C. The catalysts displayed a turnover frequency as high as 26,910 h−1 for styrene hydrogenation and maintained the catalytic activity for at least 5 test cycles.