Electron Donor Research Articles

Metagenomes from microbial populations beneath a chromium waste tip give insight into the mechanism of Cr (VI) reduction

Dumped Chromium Ore Processing Residue (COPR) at legacy sites poses a threat to health through leaching of toxic Cr(VI) into groundwater. Previous work implicates microbial activity in reducing Cr(VI) to less mobile and toxic Cr(III), but the mechanism has not been explored. To address this question a combined metagenomic and geochemical study was undertaken. Soil samples from below the COPR waste were used to establish anaerobic microcosms which were challenged with Cr(VI), with or without acetate as an electron donor, and incubated for 70 days. Cr was rapidly reduced in both systems, which also reduced nitrate, nitrite then sulfate, but this sequence was accelerated in the acetate amended microcosms. 16S rRNA gene sequencing revealed that the original soil sample was diverse but both microcosm systems became less diverse by the end of the experiment. A high proportion of 16S rRNA gene reads and metagenome-assembled genomes (MAGs) with high completeness could not be taxonomically classified, highlighting the distinctiveness of these alkaline Cr impacted systems. Examination of the coding capacity revealed widespread capability for metal tolerance and Fe uptake and storage, and both populations possessed metabolic capability to degrade a wide range of organic molecules. The relative abundance of genes for fatty acid degradation was 4× higher in the unamended compared to the acetate amended system, whereas the capacity for dissimilatory sulfate metabolism was 3× higher in the acetate amended system. We demonstrate that naturally occurring in situ bacterial populations have the metabolic capability to couple acetate oxidation to sequential reduction of electron acceptors which can reduce Cr(VI) to less mobile and toxic Cr(III), and that microbially produced sulfide may be important in reductive precipitation of chromate. This capability could be harnessed to create a Cr(VI) trap-zone beneath COPR tips without the need to disturb the waste.

Eosin Y derivatives for visible light-mediated free-radical polymerization: Applications in 3D-photoprinting and bacterial photodynamic inactivation

This study reports the design and the subsequent use of mono-allylated (EY-MA) and di-allylated (EY-DA) derivatives of eosin Y (EY) as highly efficient visible light-sensitive photosensitizers (PS) of bio-based H-donor molecules (cysteamine (Cys) or N-acetyl-L-cysteine (NAC)) and an electron donor (N-methyldiethanolamine, MDEA) for free-radical and thiol-acrylate polymerizations of a biobased monomer derived from soybean oil (SOA) upon exposure to visible light. High final acrylate conversions for SOA polymerization (up to 80 %) evidence the efficient photoinitiating properties of the eosin derivatives systems under irradiation with light emitting diodes (LEDs) centred at 405, 455 and 505 nm, and outperform those obtained with EY and other common photosensitizers such as camphorquinone or benzophenone. As described by fluorescence and phosphorescence analyses, laser flash photolysis (LFP) and electron paramagnetic resonance spin-trapping (EPR-ST) experiments, EY-MA and EY-DA can react via a proton/proton-coupled electron transfer reaction with Cys (or NAC) and MDEA respectively. The efficient singlet oxygen generation of the EY-MA-based materials upon exposure to visible light leads to excellent antibacterial properties, against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). A 3-log decrease of E. coli adhesion on the surface of the materials is observed and 100 % adhesion inhibition of S. aureus is also demonstrated. The co-polymerization of the eosin-derived PS with the polymer matrix ensures sustainable antibacterial properties against both bacteria strains upon visible light exposure as it prevents their leakage out of the polymer network. Finally, finely complex 3D structures are successfully obtained by a 3D-photoprinting technology with the investigated EY-MA-based formulation using LED@405 nm.

Using rice straw-augmented ecological floating beds to enhance nitrogen removal in carbon-limited wastewater

Agricultural biomass used as solid carbon substrates in ecological floating beds (EFBs) has been proven to be applicable in nitrogen removal for carbon-limited wastewater treatment. However, the subtle interactions among plants, rhizosphere microorganisms, and supplementary carbon sources have not been thoroughly studied. This study combined rice straw mats with different aquatic macrophytes in EFBs to investigate denitrification efficiency in carbon-limited eutrophic waters. Results showed that rice straw significantly enhanced the nitrogen removal efficiency of EFBs, while enriching nitrogen-fixing and denitrifying bacteria (such as Rhizobium, Rubrivivax, and Rhodobacter, etc.). Additionally, during the denitrification process in EFBs, rice straw can release humic acid-like fraction as electron donors to support the metabolic activities of microorganisms, while aquatic macrophytes provide a more diverse range of dissolved organic matters, facilitating a sustainable denitrification process. These findings help to understand the synergistic effect of denitrification processes within wetland ecosystems using agricultural biomass.

Treatment of Wastewaters with Different Ammonium Concentrations in a Sequencing Batch Reactor by Nitritation and Denitritation Processes

In the treatment of industrial and municipal wastewaters, biological nitrification and denitrification processes have been widely applied methods. However, in recent years, experimental studies have been carried out on nitritation and denitritation processes in order to reduce the cost of wastewater treatment. In this study, the removal of synthetic wastewaters containing ammonium at various concentrations through nitritation and denitritation processes was investigated in a sequence batch reactor (SBR). The SBR was operated at a low dissolved oxygen concentration of 0.7±0.2 mg/L, while the initial pH level and temperature were kept constant at 7.5 and 25 ℃, respectively, which were below the defined optimal level for nitritation. For the initial concentrations of 100, 150, and 200 mg NH4-N/L, 91, 142, and 180 mg NOx-N were produced, respectively with the specific nitritation rates of 0.69, 0.95, and 0.81 mg NH4-N/mg MLVSS.hour. Considering the operating conditions of nitritation, approximately NO2-N/NOx-N ratio of 80% could be considered as successful with the combined effect of DO limitation and NH3 inhibition on the nitrite oxidizing bacteria. During the first days of nitritation and denitritation processes, change of nitrogen concentrations was negligible because the adaptation of organisms to the oxic and anoxic conditions. After completing nitritation stage, denitritation was carried out by using methanol as an electron donor for the initial concentrations of 91, 142, and 180 mg/L of NOx-N in 96, 120 and 264 hours of reaction times, respectively.

Visible-Light-Driven Photocatalytic H2 Production Using Composites of Co-Al Layered Double Hydroxides and Graphene Derivatives.

The direct conversion of solar energy into chemical energy represents an enormous challenge for current science. One of the commonly proposed photocatalytic systems is composed of a photosensitizer (PS) and a catalyst, together with a sacrificial electron donor (ED) when only the reduction of protons to H2 is addressed. Layered double hydroxides (LDH) have emerged as effective catalysts. Herein, two Co-Al LDH and their composites with graphene oxide (GO) or graphene quantum dots (GQD) have been prepared by coprecipitation and urea hydrolysis, which determined their structure and so their catalytic performance, giving H2 productions between 1409 and 8643 μmol g-1 using a ruthenium complex as PS and triethanolamine as ED at 450 nm. The influence of different factors, including the integration of both components, on their catalytic behavior, has been studied. The proper arrangement between the particles of both components seems to be the determining factor for achieving a synergistic interaction between LDH and GO or GQD. The novel Co-Al LDH composite with intercalated GQD achieved an outstanding catalytic efficiency (8643 μmol H2 g-1) and exhibited excellent reusability after 3 reaction cycles, thus representing an optimal integration between graphene materials and Co-Al LDH for visible light driven H2 photocatalytic production.

Standard operating procedure for the analysis of major ions in hydrothermal fluids by ion chromatography

This standard operating procedure (SOP) describes an ion chromatography (IC) procedure for the major cations and anions in hydrothermal fluids. Hydrothermal fluids are aqueous solutions with a wide range of temperature, salinity, pH and ion species that can be used by microbial metabolism as electron donors and electron acceptors. Due to the high variability of the environmental physical-chemical parameters in these samples, we have developed this protocol taking into account the special features of the matrices analyzed. An Eco IC Metrohm system equipped with a conductivity detector was used. Calibration curves are linear in the 0.1 to 10 mg/L concentration range for cations Ca2+, Na+, K+, Mg2+, NH4 + and anions Cl-, Br-, NO3 -, NO2 -, SO4 2- , HPO4 2-.

Production of redox-active-reactive filter material from charcoal

The surficial and textural features of a pyrogenic carbonaceous material (charcoal) was modulated with acidic Piranha solution (i.e., 1:3 30% H2O2 to H2SO4) to produce a redox-active adsorbent for the simultaneous adsorption and reduction of Cr(VI) in groundwater sample. The optimal modification time of 60 s is required to transform the raw charcoal to an efficacious redox-active adsorbent (MCh). The MCh surface was imbued with electron donor moieties that is required for the direct conversion of the adsorbed Cr(VI) to Cr(III). The rate parameters for Cr(VI) adsorption by the MCh were initial concentration dependent. The GW system variables had minimal influence on the performance of the MCh, which showed that the MCh is capable of effective performance within broad process variables. The direct conversion of Cr(VI) to Cr(III) on the MCh surface was affirmed. The treatment of Cr(VI) contaminated GW in a microcosm real-life system was highly effective over the period of study (40 hours). The residual Cr(VI) concentration in the hourly sample collection ranged between undetectable (i.e.,<0.01), at the inception, to 1.77 mg/L at the 40th hour. The pH values of the treated water were not vitiated, and the EC (μs cm− 1) values continually reduced over time.

Sustainable Napier Grass (Pennisetum purpureum) Biochar for the Sorptive Removal of Acid Orange 7 (AO7) from Water

The unregulated discharge of synthetic dyes from various anthropogenic and industrial activities has resulted in the contamination of different environmental compartments. These dyes can contaminate water bodies, soil, and even the air, resulting in many environmental and health issues. True colors may persist for long periods, thereby affecting the aesthetics and ecology of dye-contaminated areas. Furthermore, they pose potential risks to aquatic life and human health through the ingestion or absorption of dye-contaminated water or food. Acid orange 7 (AO7) is a synthetic azo dye used in the textile, tanning, food, pharmaceutical, paint, electronics, cosmetics, and paper and pulp industries. AO7 can have various human health implications, such as dermatitis, nausea, severe headache, respiratory tract irritation, and bone marrow depletion, due to its high toxicity, mutagenicity, and carcinogenicity. Efforts to regulate and mitigate dye pollution (AO7) are crucial for environmental sustainability and public health. Therefore, this study aimed to remove AO7 from water using sustainable biochar. This objective was accomplished by pyrolyzing dried Napier grass at 700 °C to develop affordable and sustainable Napier grass biochar (NGBC700). The developed biochar was characterized for its surface morphology, surface functional groups, surface area, and elemental composition. The yield, moisture content, and ash content of the NGBC700 were approximately 31%, 6%, and 21%, respectively. The NGBC700’s BET (Brunauer–Emmett–Teller) surface area was 108 . Batch sorption studies were carried out at different pH levels (2–10), biochar dosages (1, 2, 3, and 4 ), and AO7 concentrations (10, 20, and 30 . The kinetic data were better fitted to the pseudo-second-order (PSO) equation (R2 = 0.964–0.997) than the pseudo-first-order (PFO) equation (R2 = 0.789–0.988). The Freundlich isotherm equation (R2 = 0.965–0.994) fitted the sorption equilibrium data better than the Langmuir equation (R2 = 0.788–0.987), suggesting AO7 sorption on heterogenous NGBC700. The maximum monolayer AO7 adsorption capacities of the NGBC700 were 14.3, 12.7, and 8.4 at 10, 25, and 40 °C, respectively. The column AO7 sorption capacity was 4.4. Fixed-bed AO7 sorption data were fitted to the Thomas and Yoon–Nelson column models. The NGBC700 efficiently removed AO7 from locally available dye-laden wastewater. NGBC700 was regenerated using different NaOH concentrations. Possible interactions contributing to AO7 sorption on NGBC700 include hydrogen bonding, electrostatic interactions, and π–π electron donor–acceptor attractions. The estimated total preparation cost of NGBC700 was US$ 6.02 kg−1. The developed sustainable NGBC700 is potentially cost-effective and environmentally friendly, and it utilizes waste (Napier grass) to eliminate fatal AO7 dye from aqueous media.

BiVO4 Photoanode with NiV2O6 Back Contact Interfacial Layer for Improved Hole-Diffusion Length and Photoelectrochemical Water Oxidation Activity.

The short hole diffusion length (HDL) and high interfacial recombination are among the main drawbacks of semiconductor-based solar energy systems. Surface passivation and introducing an interfacial layer are recognized for enhancing HDL and charge carrier separation. Herein, we introduced a facile recipe to design a pinholes-free BiVO4 photoanode with a NiV2O6 back contact interfacial (BCI) layer, marking a significant advancement in the HDL and photoelectrochemical activity. The fabricated BiVO4 photoanode with NiV2O6 BCI layer exhibits a 2-fold increase in the HDL compared to pristine BiVO4. Despite this improvement, we found that the front surface recombination still hinders the water oxidation process, as revealed by photoelectrochemical (PEC) studies employing Na2SO3 electron donors and by intensity-modulated photocurrent spectroscopy measurements. To address this limitation, the surface of the NiV2O6/BiVO4 photoanode was passivated with a cobalt phosphate electrocatalyst, resulting in a dramatic enhancement in the PEC performance. The optimized photoanode achieved a stable photocurrent density of 4.8 mA cm-2 at 1.23 VRHE, which is 12-fold higher than that of the pristine BiVO4 photoanode. Density Functional Theory (DFT) simulations revealed an abrupt electrostatic potential transition at the NiV2O6/BiVO4 interface with BiVO4 being more negative than NiV2O6. A strong built-in electric field is thus generated at the interface and drifts photogenerated electrons toward the NiV2O6 BCI layer and photogenerated holes toward the BiVO4 top layer. As a result, the back-surface recombination is minimized, and ultimately, the HDL is extended in agreement with the experimental findings.

A high-efficiency photocatalytic hydrogen evolution system based on nickel-quinoxaline dithiolate complexes and water-soluble CdSe quantum dots

Photocatalytic water splitting of water for hydrogen evolution is one of the effective methods to obtain clean hydrogen energy. In the present work, the following materials were synthesized: two nickel quinoxaline thiolate complexes [NBu4]2 [Ni(qdt)2] (1, Bu = n-butyl, qdt = quinoxaline-dithiol), [NBu4]2 [Ni(qdt)2(NO2)2] (2) and water-soluble MPA-CdSe quantum dots (MPA-CdSe QDs, MPA = 3-mercaptopropionic acid). Subsequently, an efficient three-component photocatalytic hybrid system for hydrogen evolution was developed and tested under visible light irradiation, in which one of the target complex 1 or 2 was used as the catalyst, triethylamine (TEA) was used as the sacrificial electron donor, and MPA-CdSe QDs were used as the light harvesting reagent. The turnover numbers (TON) for H2 evolution of 8974 (vs. complex 1) and 6532 (vs. complex 2) were obtained under the optimal conditions with TEA concentration of 5 %, pH = 12, and concentration of complex 1 or 2 of 1 × 10−5 mol L−1 after 13 h of irradiation (λ > 420 nm) in pure water. The mechanism investigation indicated that critical steps of hydrogen production was formation of hydride intermediates Ni(II)-H and Ni(I)-H spices, followed by the reaction of two Ni(II)-H or Ni(I)-H species with protons generating H2 molecules and regenerating the catalyst Ni(II).

High‐Energy Nitrogen Rings Stabilized by Superatomic Properties

AbstractHow to stabilize nitrogen‐rich high‐energy‐density molecules under conventional conditions is particularly important for the energy storage and conversion of such systems and has attracted extensive attention. In this work, the theoretical study shows for the first time that the stabilization mechanism of the nitrogen ring conforms to the superatomic properties at the atomic level. This result occurs because the stabilized anionic nitrogen rings generally exhibit planar high symmetry and the injected electrons occupy the superatomic molecular orbitals (SAMOs) of the nitrogen rings. According to these results, the typical stabilized anionic nitrogen ring structures N64−, N5−, and N42− are identified, which possess delocalized molecular orbitals with the same symmetry as the atomic orbitals and electron arrangement consistent with the electron shell arrangement of the atom. On this basis, a pathway is further designed to stabilize nitrogen rings by introducing metal atoms as electron donors to form neutral ThN6, LiN5, and MgN4 structures, thereby replacing the anionization of systems. This study highlights the importance of developing nitrogen‐rich energetic materials from the perspective of superatoms.

Efficient Intra‐Supramolecular Electron Transfer in Zinc Porphyrin‐Coumarin Dyads

AbstractWe report herein the electron transfer process of a novel supramolecular dyads composed of zinc tetraphenylporphyrin (ZnTPP) and zinc 5,15‐dinonyl‐10,20‐diphenylporphyrin (ZnDPP), as electron donors, and ethyl(4‐pyridyl) coumarin‐3‐carboxylate (EPCC), as an electron acceptor, through metal‐ligand coordination bond in dichloromethane. The optical absorption studies revealed the formation of the moderate stable supramolecular donor‐acceptor dyads. The fluorescence measurements showed a significant fluorescence quenching of the singlet‐excited state of the singlet‐excited states of ZnTPP and ZnDPP upon addition of different amounts of EPCC. Such quenching behavior could be attributed to the electron transfer from the singlet‐excited state of porphyrin to EPCC. The bimolecular quenching rates were determined to be 1.98×1012 and 7.59×1012 L mol−1 s−1 for ZnTPP‐EPCC and ZnDPP‐EPCC, respectively, respectively. The fluorescence lifetime measurements suggest fast and efficient intra‐supramolecular electron transfer from the singlet states of porphyrin derivatives to EPCC. Furthermore, the formation of the supramolecular dyads was confirmed by the Raman technique and computational studies. The finding that the examined zinc porphyrin ‐ coumarin supramolecular dyads absorb light in a wide range of UV‐visible spectrum, fast and efficient electron transfer render the examined supramolecular dyad as simple models for the reaction centers of the artificial photosynthetic systems.

Dicyanomethylenated Diaryldihydropentalenediones that Vary Excited State Decay Rates without Changing Emission Wavelengths

2‐(3,6‐Bis(4‐methoxyphenyl)‐2,2,5,5‐tetramethyl‐4‐oxo‐4,5‐dihydropentalen‐1(2H)‐ylidene)malononitrile (DPM‐An) and 2,2'‐(3,6‐bis(4‐methoxyphenyl)‐2,2,5,5‐tetramethyl‐2,5‐dihydropentalene‐1,4‐diylidene)dimalononitrile (DPD‐An), both bearing the 2,5‐dihydropentalene core and intramolecular electron donor–acceptor moieties, were prepared and subjected to photophysical studies. The absorption spectra of DPM‐An and DPD‐An in CH2Cl2 at room temperature contain maxima at similar wavelengths of 406 and 409 nm, respectively. These substances do not luminesce in CH2Cl2 solution at room temperature, but they do emit light when present in poly(methyl methacrylate) films. Interestingly, DPM‐An and DPD‐An in the film forms display nearly identical emission (EM) spectra with respective maxima at 592 and 594 nm. In contrast, DPD‐An has a longer EM lifetime than does DPM‐An. Therefore, the dihydropentalene derivatives, exemplified by DPM‐An and DPD‐An, may be a family of substances in which excited state decay rate can be varied without changing EM wavelengths.

Direct observation of electron transfer in solids through X-ray crystallography

Nanoscale electron transfer (ET) in solids is fundamental to the design of multifunctional nanomaterials, yet its process is not fully understood. Herein, through X-ray crystallography, we directly observe solid-state ET via a crystal-to-crystal process. We first demonstrate the creation of a robust and flexible electron acceptor/acceptor (A/A) double-wall nanotube crystal ([(Zn2+)4(LA)4(LA=O)4]n) with a large window (0.90 nm × 0.92 nm) through the one-dimensional porous crystallization of heteroleptic Zn4 metallocycles ((Zn2+)4(LA)4(LA=O)4) with two different acceptor ligands (2,7-bis((1-ethyl-1H-imidazol-2-yl)ethynyl)acridine (LA) and 2,7-bis((1-ethyl-1H-imidazol-2-yl)ethynyl)acridin-9(10H)-one (LA=O)) in a slow-oxidation-associated crystallization procedure. We then achieve the bottom-up construction of the electron donor incorporated-A/A nanotube crystal ([(D)2⊂(Zn2+)4(LA)4(LA=O)4]n) through the subsequent absorption of electron donor guests (D = tetrathiafulvalene (TTF) and ferrocene (Fc)). Finally, we remove electrons from the electron donor guests inside the nanotube crystal through facile ET in the solid state to accumulate holes inside the nanotube crystal ([(D•+)2⊂(Zn2+)4(LA)4(LA=O)4]n), where the solid-state ET process (D – e– → D•+) is thus observed directly by X-ray crystallography.

Sulfide oxidation by members of the Sulfolobales

Abstract The oxidation of sulfur compounds drives the acidification of geothermal waters. At high temperatures (&amp;gt;80°C) and in acidic conditions (pH &amp;lt;6.0), oxidation of sulfide has historically been considered an abiotic process that generates elemental sulfur (S0) that, in turn, is oxidized by thermoacidophiles of the model archaeal order Sulfolobales to generate sulfuric acid (i.e., sulfate and protons). Here, we describe five new aerobic and autotrophic strains of Sulfolobales comprising two species that were isolated from acidic hot springs in Yellowstone National Park (YNP) and that can use sulfide as an electron donor. These strains significantly accelerated the rate and extent of sulfide oxidation to sulfate relative to abiotic controls, concomitant with production of cells. Yields of sulfide-grown cultures were ∼2-fold greater than those of S0-grown cultures, consistent with thermodynamic calculations indicating more available energy in the former condition than the latter. Homologs of sulfide:quinone oxidoreductase (Sqr) were identified in nearly all Sulfolobales genomes from YNP metagenomes as well as those from other reference Sulfolobales, suggesting a widespread ability to accelerate sulfide oxidation. These observations expand the role of Sulfolobales in the oxidative sulfur cycle, the geobiological feedbacks that drive the formation of acidic hot springs, and landscape evolution.

Time-Resolved Mechanistic Depiction of Photoinduced CO2 Reduction Catalysis on a Urea-Modified Iron Porphyrin.

The development of functional artificial photosynthetic devices relies on the understanding of mechanistic aspects involved in specialized photocatalysts. Modified iron porphyrins have long been explored as efficient catalysts for the light-induced reduction of carbon dioxide (CO2) towards solar fuels. In spite of the advancements in homogeneous catalysis, the development of the next generation of catalysts requires a complete understanding of the fundamental photoinduced processes taking place prior to and after activation of the substrate by the catalyst. In this work, we employ a state-of-the-art nanosecond optical transient absorption spectroscopic setup with a double excitation capability to induce charge accumulation and trigger the reduction of CO2 to carbon monoxide (CO). Our biomimetic system is composed of a urea-modified iron(III) tetraphenylporphyrin (UrFeIII) catalyst, the prototypical [Ru(bpy)3]2+ (bpy = 2,2'-bipyridine) used as a photosensitizer, and sodium ascorbate as an electron donor. Under inert atmosphere, we show that two electrons can be successively accumulated on the catalyst as the fates of the photogenerated UrFeII and UrFeI reduced species are tracked. In the presence of CO2, the catalytic cycle is kick-started providing further evidence on CO2 activation by the UrFe catalyst in its formal FeI oxidation state.

Time‐Resolved Mechanistic Depiction of Photoinduced CO2 Reduction Catalysis on a Urea‐Modified Iron Porphyrin

The development of functional artificial photosynthetic devices relies on the understanding of mechanistic aspects involved in specialized photocatalysts. Modified iron porphyrins have long been explored as efficient catalysts for the light‐induced reduction of carbon dioxide (CO2) towards solar fuels. In spite of the advancements in homogeneous catalysis, the development of the next generation of catalysts requires a complete understanding of the fundamental photoinduced processes taking place prior to and after activation of the substrate by the catalyst. In this work, we employ a state‐of‐the‐art nanosecond optical transient absorption spectroscopic setup with a double excitation capability to induce charge accumulation and trigger the reduction of CO2 to carbon monoxide (CO). Our biomimetic system is composed of a urea‐modified iron(III) tetraphenylporphyrin (UrFeIII) catalyst, the prototypical [Ru(bpy)3]2+ (bpy = 2,2’‐bipyridine) used as a photosensitizer, and sodium ascorbate as an electron donor. Under inert atmosphere, we show that two electrons can be successively accumulated on the catalyst as the fates of the photogenerated UrFeII and UrFeI reduced species are tracked. In the presence of CO2, the catalytic cycle is kick‐started providing further evidence on CO2 activation by the UrFe catalyst in its formal FeI oxidation state.

Directional Formation of Reactive Oxygen Species Via a Non-Redox Catalysis Strategy That Bypasses Electron Transfer Process.

A broad range of chemical transformations driven by catalytic processes necessitates the electron transfer between catalyst and substrate. The redox cycle limitation arising from the inequivalent electron donation and acceptance of the involved catalysts, however, generally leads to their deactivation, causing substantial economic losses and environmental risks. Here, a "non-redox catalysis" strategy is provided, wherein the catalytic units are constructed by atomic Fe and B as dual active sites to create tensile force and electric field, which allows directional self-decomposition of peroxymonosulfate (PMS) molecules through internal electron transfer to form singlet oxygen, bypassing the need of electron transfer between catalyst and PMS. The proposed catalytic approach with non-redox cycling of catalyst contributes to excellent stability of the active centers while the generated reactive oxygen species find high efficiency in long-term catalytic pollutant degradation and selective organic oxidation synthesis in aqueous phase. This work offers a new avenue for directional substrate conversion, which holds promise to advance the design of alternative catalytic pathways for sustainable energy conversion and valuable chemical production.

Enhanced Efficiency and Stability of Wide‐Bandgap Perovskite Solar Cells Via Molecular Modification with Piperazinium Salt

AbstractWide‐bandgap (WBG) perovskite solar cell (PSC) plays a pivotal role as the top subcell in all‐perovskite tandem solar cells (TSCs), facilitating the absorption of high‐energy photons and affording a large open‐circuit voltage (VOC). Nonetheless, the stability and efficiency of WBG PSCs are constrained by light‐induced halide segregation and non‐radiative recombination losses. In this study, this work presents an approach of utilizing 2‐methylpiperazinium bromide (2‐MePBr) via interfacial engineering to realize high‐efficiency WBG (1.77 eV) PSCs. The C─NH─C functional group in 2‐MePBr, serving as an electron donor, can interact with under‐coordinated lead defects at the perovskite surface. Consequently, the treatment with 2‐MePBr mitigates interfacial non‐radiative recombination, enhances charge transport, inhibits ion migration, and thus delivers an improved power conversion efficiency (PCE) of 19.30% with a VOC of 1.29 V, and a fill factor of 83.08%. Notably, the WBG PSCs manifest enhanced stability, preserving 80% of the initial PCE after 337 h of continuous operation under 1 sun illumination at the maximum power point. Furthermore, the all‐perovskite TSCs based on this WBG subcell achieve a PCE of 27.47%, showing its promising application in perovskite‐based tandem solar cells.

Effect of chalcogen atoms on the electronic band gaps of the quinoxaline containing donor-acceptor-donor type semiconducting polymers: a systematic DFT investigation.

Due to the widely known positive contributions of the quinoxaline group in organic semiconductors, we conducted a fully computational study using quantum mechanical methods to investigate the effect of quinoxaline in the electron acceptor unit with the combination of different chalcogen atoms on the band gap of a series of donor-acceptor-donor type conjugated polymers. Using density functional theory, we mainly calculated the electronic band gap values of the structures containing four different chalcogen atoms (O, S, Se, and Te) in the electron donor and acceptor units. While chalcogendiazoloquinoxaline groups were used as the electron acceptor units, furan, thiophene, selenophene, and tellurophene were used as the donor units. Our theoretical results showed that the use of heavy chalcogen atoms in both donor and acceptor units resulted in a low band gap. Besides this, the effect of heavy chalcogen atoms used in the electron donor units is much more pronounced compared to the ones used in the acceptor units. More importantly, our findings proved that the inclusion of the chalcogendiazoloquinoxaline group instead of benzochalcogenadiazole as the acceptor unit significantly decreases the electronic band gap of the conjugated polymer. The lowest band gap was found to be 0.10eV for the 4,9-di(tellurophen-2-yl)-[1,2,5]telluradiazolo[3,4-g]quinoxaline polymer. Conformational analysis of the monomers and their corresponding oligomers was performed at the B3LYP/LANL2DZ level of theory. Then, long-range corrected hybrid functional LC-BLYP in a combination with the LANL2DZ basis set was utilized for the calculation of electronic properties and HOMO and LUMO energy gaps of monomers and oligomers through the reoptimization of the lowest energy conformers obtained from the B3LYP/LANL2DZ calculations in the previous step. All energy minimum structures were confirmed through vibrational frequency analysis at both calculation levels. The Gaussian 09 rev. D.01 software was used for all calculations, and GaussView 5.0.9 for visualizations.