Intermediate Species Research Articles

Integrated CO2 capture and dynamic catalysis for CO2 recycling in a microbrewery

In this study, we used fermentation off-gases from a brewery for integrated CO2 capture and utilisation in order to produce CH4 with a dual-function material (DFM) containing NiRu as catalyst and dispersed CaO as adsorbent. CH4 was produced from captured CO2 via 2 pathways (fast and slow), proceeding through formyl intermediates according to the operando DRIFTS-MS results. The NiRuCa DFM showed a stable CH4 capacity over 8 cycles (105 μmol/gDFM) with fermentation off-gases being used as a CO2 capture feed. H2O and O2, which were present in small amounts in the emissions feed, resulted in the passivation of Ni in the form of a NiO layer and hence, the DFM did not undergo excessive oxidation and deactivation. This work constitutes a first in terms of validating the use of DFMs with real industrial emissions, and it directly correlates the DFM activity performance with its reaction mechanism and intermediate species.

Metal-support interaction in supported Pt single-atom catalyst promotes lattice oxygen activation to achieve complete oxidation of acetone at low concentrations

A precious metal catalyst with loaded Pt single atoms was prepared and used for the complete oxidation of C3H6O. Detailed results show that the T100 of the 1.5Pt SA/γ-Al2O3 catalyst in the oxidation process of acetone is 250 °C, the TOF of Pt is 1.09 × 10−2 s−1, and the catalyst exhibits good stability. Characterization reveals that the high dispersion of Pt single atoms and strong interaction with the carrier improve the redox properties of the catalyst, enhancing the adsorption and dissociation capability of gaseous oxygen. DFT calculations show that after the introduction of Pt, the oxygen vacancy formation energy on the catalyst surface is reduced to 1.2 eV, and PDOS calculations prove that electrons on Pt atoms can be quickly transferred to O atoms, increasing the number of electrons on the σp * bond and promoting the escape of lattice oxygen. In addition, in situ DRIFTS and adsorption experiments indicate that the C3H6O oxidation process follows the Mars-van Krevelen reaction mechanism, and CH2 =C(CH3)=O(ads), O* (O2-), formate, acetate, and carbonate are considered as the main intermediate species and/or transients in the reaction process. Particularly, the activation rate of O2 and the cleavage of the -C-C- bond are the main rate-determining steps in the oxidation of C3H6O. This work will further enhance the study of the oxidation mechanism of oxygenated volatile organic pollutants over loaded noble metal catalysts.

Research on the microstructure and mechanical properties of functional gradient materials of TC4/TC11 titanium alloys for wire arc additive manufacturing with different transitional forms

Functional gradient materials (FGMs) have garnered increasing interest for their potential in material and structural design. Additive manufacturing, as a kind of free manufacturing and near-net shaping technology with in-situ controllability of materials, is the dominant technology for fabricating FGMs. While numerous studies have been conducted on titanium alloy FGMs, there is still a lack of research on the structure and properties of the material with the number of transitional layers. This study employs double-wire arc additive manufacturing to fabricate FGMs composed of TC4 and TC11 alloys. The study examines the utilization of direct and continuous transition forms in conjunction with stress relieving and solution aging heat treatment processes. The composition, grain morphology, microstructure, and mechanical properties of FGMs are analyzed. Results indicate that in samples employing direct transition, higher heat treatment temperatures and durations lead to a more uniform composition and microstructure. Additionally, the interface morphology becomes increasingly indistinct, and transversal elongation at the interface is enhanced by the strain compensation of the two materials. In continuous transitional samples, an increase in the number of transitional layers results in a more uniform microstructure near the interface, leading to a reduction in interface morphology and an enhancement of mechanical properties. The fracture position tends to shift closer to the TC4 side, with both process forms exhibiting ductile fractures. The plasticity of the TC4 part is superior, and the ductile fracture morphology is more pronounced. This study offers a valuable experimental foundation for investigating the direct and continuous transition of titanium alloy FGMs.

Cocatalyst Embedded Ce-BDC-CeO2 S-Scheme Heterojunction Hollowed-Out Octahedrons With Rich Defects for Efficient CO2 Photoreduction.

Constructing heterojunction photocatalysts with optimized architecture and components is an effective strategy for enhancing CO2 photoreduction by promoting photogenerated carrier separation, visible light absorption, and CO2 adsorption. Herein, defect-rich photocatalysts (Ni2P@Ce-BDC-CeO2 HOOs) with S-scheme heterojunction and hollowed-out octahedral architecture are prepared by decomposing Ce-BDC octahedrons embedded with Ni2P nanoparticles and subsequent lactic acid etching for CO2 photoreduction. The hollowed-out octahedral architecture with multistage pores (micropores, mesopores, and macropores) and oxygen vacancy defects are simultaneously produced during the preparation process. The S-scheme heterojunction boosts the quick transfer and separation of photoinduced charges. The formed hollowed-out multi-stage pore structure is favorable for the adsorption and diffusion of CO2 molecules and gaseous products. As expected, the optimized photocatalyst exhibits excellent performance, producing CO with a yield of 61.6µmolh-1g-1, which is four times higher than that of the original Ce-BDC octahedrons. The X-ray photoelectron spectroscopy, scanning Kelvin probe, and electron spin resonance spectroscopy characterizations confirm the S-schematic charge-transfer route. The key intermediate species during the CO2 photoreduction process are detected by in situ Fourier transform infrared spectroscopy to support the proposed mechanism for CO2 photoreduction. This work presents a synthetic strategy for excellent catalysts with potential prospects in photocatalytic applications.

Highly efficient removal of ozone on amorphous manganese oxides modified by alkali metals

Low stability deriving from the accumulation of moisture and intermediates represents the major challenge for practical applications of manganese oxides (MnOx) for ozone elimination. Here, Li+, Na+ and K+ were successfully introduced into the channel framework of amorphous MnOx to improve its stability through a simple post-treatment method. Alkali metal modification can promote the removal of ozone by amorphous MnOx, and Na-MnOx exhibited superior catalytic activity and remarkable stability in water-resistance, cycling and long-term tests. The Na introduction facilitated the formation of oxygen vacancies, and improved low-temperature reducibility and lattice oxygen mobility. The mechanism of ozone decomposition on amorphous MnOx and Na-MnOx catalysts was deeply investigated by in situ diffuse reflectance infrared Fourier transform spectra (in-situ DRIFTS). The Na addition strengthened the hydrophobicity of oxygen vacancies, but also greatly boosted the desorption of intermediate oxygen species and the ozone decomposition cycle.

A second-order kinetic model for global analysis of vibrational polariton dynamics.

The interaction between cavity photons and molecular vibrations leads to the formation of vibrational polaritons, which have demonstrated the ability to influence chemical reactivity and change material characteristics. Although ultrafast spectroscopy has been extensively applied to study vibrational polaritons, the nonlinear relationship between signal and quantum state population complicates the analysis of their kinetics. Here, we employ a second-order kinetic model and transform matrix method (TMM) to develop an effective model to capture the nonlinear relationship between the two-dimensional IR (or pump-probe) signal and excited state populations. We test this method on two types of kinetics: a sequential relaxation from the second to the first excited states of dark modes, and a Raman state relaxing into the first excited state. By globally fitting the simulated data, we demonstrate accurate extraction of relaxation rates and the ability to identify intermediate species by comparing the species spectra with theoretical ground truth, validating our method. This study demonstrates the efficacy of a second-order TMM approximation in capturing essential spectral features with up to 10% excited state population, simplifying global analysis and enabling straightforward extraction of kinetic parameters, thus empowering our methodology in understanding excited-state dynamics in polariton systems.

Carrier-phase direct numerical simulation and flamelet modeling of NOx formation in a pulverized coal/ammonia co-firing flame

A carrier-phase direct numerical simulation (CP-DNS) of a coal/ammonia co-firing flame in a turbulent mixing layer is performed with a detailed chemical reaction mechanism including NOx formation. The combustion characteristics and NOx formation mechanism of the coal/ammonia co-firing flame are investigated in detail through a conditional reaction pathway analysis. A new four-fuel-stream flamelet model is proposed to adapt to the piloted pulverized coal/ammonia co-combustion system, in which the complex mixing among the volatiles, char off-gases, ammonia, and the pilot stream is characterized with four mixture fractions. The flamelet solutions in the fourfold mixture fraction space are transformed into a uniform space to facilitate the access to the flamelet table. The performance of the flamelet model is evaluated through an a priori analysis, a combustion mode analysis, and a chemical timescale analysis. For the turbulent coal/ammonia co-firing flame studied, two distinct flame fronts within the shear layer are observed with the upper part being dominated by ammonia combustion and the lower part being governed by coal combustion. The conditional analyses show that NO species is mainly generated by the lower layer governed by pulverized coal combustion where the nitrogen-containing species from volatile combustion are highly involved in the NO formation. The NO concentration first increases with decreasing the fraction of ammonia in the local computational cell, and then decreases towards pure pulverized coal combustion, which is characterized with a newly introduced manifold coordinate. While the temperature and the major and intermediate species mass fractions in the coal/ammonia co-firing flame can be reasonably predicted by the proposed flamelet model, the NOx species mass fractions are not well predicted in the region where pulverized coal combustion dominates. It is clarified that the inaccurate prediction of the NOx species is not caused by interpolation errors, multiple combustion modes or the kinetics of NOx formation, but mainly attributed to the definition of the progress variable.Novelty and significance statementThe novelty of this research is the first DNS of a coal/ammonia co-firing flame in a turbulent mixing layer, and the proposal of a new flamelet tabulation method for predicting NOx formation in the coal/ammonia co-firing flame. It is significant because• Coal/ammonia co-firing promises to provide continuous, secure power supply at a much reduced carbon footprint compared to pure coal combustion;• The underlying physics governing the coal/ammonia co-firing are analyzed using carrier-phase DNS;• The performance of the newly proposed flamelet model in predicting the NOx species is evaluated based on the DNS dataset.

Acid-catalyzed Transformation of Nitrite to Nitric Oxide on Copper(II)-Cobalt(II) Centers in a Bimetallic Complex.

Nitrite (NO2 -) serves as a pool of nitric oxide (NO) in biological systems under hypoxic conditions, and it is transformed to NO by nitrite reductase (NiR) enzyme in the presence of acid (H+ ions). However, NO synthases (NOSs) generate NO via L-arginine oxidation in normoxic conditions. Previously, acid-induced NO2 - reduction chemistry was modeled on mono-metallic 3d-metals, generating metal-nitrosyls or NO(g) with H2O or H2O2 products. Herein, to understand the relative potency of a bimetallic system, we report the acid-induced reductive conversion of η2-bound NO2 - to NO on CuII-CoII centers of a hetero-bimetallic CuII-nitrito-CoII complex, [(LN8H)CuII-NO2 --CoII]3+ (CuII-NO2 --CoII, 2) bearing an octadentate N8-cryptand ligand (LN8H). The CuII-NO2 --CoII generates [CuII(LN8H)CoII]4+ (1) upon reaction with one equiv. acid (HClO4, H+ ions source) with NO(g) via a presumed transient nitrousacid (ONOH) intermediate species. Likewise, this NO2 - reduction was found to form H2O, which is believed to be from the decomposition of H2O2, an intermediate species. In addition, complex 2, in the presence of more than one equiv. H+ ions also showed the formation of NO(g) with H2O. Mechanistic investigations, using 15N-labeled-15NO2 -, 18O-labeled-18O14N16O- and 2H-labeled-DClO4 (D+ source), revealed that the N-atom and O-atom in the 14/15NO and 14N18O gases are derived from NO2 - ligand and H-atom in H2O derived from H+-source, respectively.

Improved light-cone harmonic oscillator model for the ϕ -meson longitudinal leading-twist light-cone distribution amplitude and its effects to Ds+→ϕℓ+νℓ

In the present paper, we study the properties of ϕ-meson longitudinal leading-twist light-cone distribution amplitude ϕ2;ϕ∥(x,μ) by starting from a light-cone harmonic oscillator model for its wave function. To fix the input parameters, we derive the first ten order ξ moments of ϕ2;ϕ∥(x,μ) by using the QCD sum rules approach under the background field theory. The curves of ϕ2;ϕ∥(x,μ=2 GeV) tend to be a single-peak behavior, which is consistent with the latest lattice QCD result. To show how the twist-3 light-cone distribution amplitudes (LCDAs) affect the results, we consider two scenarios for the ϕ-meson chiral twist-3 LCDAs ϕ3;ϕ⊥(x) and ψ3;ϕ⊥(x), i.e., the ones using the Wandzura-Wilczek approximation with ϕ2;ϕ∥(x,μ) (S1) and the ones using self-consistent conformal expansion with second-order Gegenbauer moments a2;ϕ2 in this work (S2). As an application, we derive the Ds+→ϕ transition form factors (TFFs) by using the QCD light-cone sum rules. The TFFs at large recoil point for those two scenarios are given separately. As for the two TFF ratios γV and γ2, we obtain γV(S1)=1.755−0.005+0.008, γ2(S1)=0.852−0.133+0.135, γV(S2)=1.723−0.021+0.023, and γ2(S2)=0.785−0.104+0.100. After extrapolating those TFFs to the physically allowable region, we then obtain the transverse, longitudinal, and total decay widths for semileptonic decay Ds+→ϕℓ+νℓ. Then the branching fractions are B(S1)(Ds+→ϕe+νe)=(2.347−0.191+0.342)×10−3, B(S1)(Ds+→ϕμ+νμ)=(2.330−0.190+0.341)×10−3, B(S2)(Ds+→ϕe+νe)=(2.367−0.132+0.256)×10−3, and B(S2)(Ds+→ϕμ+νμ)=(2.349−0.132+0.255)×10−3, which show good agreement with the data issued by the BESIII, CLEO, and Collaborations. We finally calculate Ds+→ϕℓ+νℓ polarization and asymmetry parameters, which can be measured and tested in future experiments. Published by the American Physical Society 2024

Synergistic removal of nitrogen oxides and toluene and their interaction mechanism on Cu-MnO2 catalyst

Volatile organic compounds (VOCs) and nitrogen oxides (NOx) contribute significantly to the formation of haze and photochemical smog, posing substantial threats to both the environment and human health. Toluene, a typical VOCs, often coexists with NOx in various mobile or stationary flue gases. However, the current understanding of the mutual influence of their synergistic removal remains limited. In this work, the Cu-MnO2 catalyst was prepared using the precipitation method, which demonstrated synergistic removal activity for both NOx and toluene, as well as selectivity towards N2 and CO2. The interaction mechanism was investigated, particularly focusing on the effect of NOx on the adsorption and oxidation performance of toluene. The degree to which NOx inhibits toluene increases with NOx concentration. Furthermore, multiple inhibition ways of NOx on toluene oxidation were discovered, including competitive adsorption of NOx and toluene on the catalyst surface, as evidenced by the breakthrough experiments. TPD and XPS characterization indicated that the addition of NOx reduces oxygen vacancies, thereby weakening toluene oxidation performance. In addition, in-situ DRIFT characterization was conducted, and it was found that the addition of NOx affected the oxidation process of toluene. Apart from benzyl alcohol, benzaldehyde, and benzoic acid, intermediate nitrite species also appeared, and their deposition was also the reason for the decrease in toluene oxidation ability. This work provides new insights into the interaction mechanisms between various components in the collaborative removal of NOx and VOCs.

Exploring the synergistically enhanced activity of novel α-MnSe/ppy composite for superior OER catalyst in alkaline medium

The extremely slow kinetics of the water-splitting process stymies the synthesis of hydrogen (H2) from water. To comprehend the main obstacle to the oxygen evolution reaction (OER), it is also necessary to enhance the development of efficient OER electrocatalysts. In this work, manganese selenide with polypyrrole heterostructure is synthesized, described, and electrochemically assessed as an effectiveelectrocatalystfor OER. The novel synthesized materialis characterizedusing a variety of techniques, including scanning electron microscopy (SEM), powder x-ray diffraction (PXRD), transmission electron microscopy (TEM) etc. The unique α-MnSe/ppy composite catalyst is shown to be exceedingly efficient, starting the OER at an astoundingly low voltage of 168 mV (vs. reversible hydrogen electrode [RHE]) at 10 mA cm−2, with a tafel slope of 67 mV dec-1. Also, operando UV–Vis spectro-electrochemical studies give an insight towards the intermediate species formed during the OER catalysis. Under similar electrochemical conditions, the α-MnSe/ppy electrocatalyst outperforms its α-MnSe and ppy counterparts for OER in an aqueous KOH (1.0 M) solution. These results surpass benchmark electrocatalysts made of Mn and rare earth metals. With this invention, a desired non-noble metal is made available that works excellently as an OER electrocatalyst.

Reaction mechanism of 1,2-dichlorobenzene oxidation over MnOX-CeO2 and the effect of simultaneous NO selective reduction

MnOX-CeO2 formulation has been studied for the catalytic oxidation of 1,2-dichlorobenzene. Among the samples with different Mn and Ce content, the most active was 85%mol Mn and 15%mol Ce, due to its better morphological properties and the synergy achieved between the two phases composing it (mixed oxide phase and segregated Mn oxide). Deactivation was monitored at low temperature and a transient change in the oxidative capability at high temperature because of active sites with different oxidative capability. Based on in-situ FTIR results, oxidation reaction pathway is proposed. Active sites with different oxidative capability causes some reaction steps to occur faster than others as a function of temperature, which modifies the distribution of intermediate species. In the reduction of NO, its adsorption leads to nitrate species contributing to a faster re-oxidation of active sites and the presence of NH3 promotes the removal of adsorbed Cl.

Where should I perch? The effects of body size, height, and leaf surface on the vertical perching position of dung beetles (Scarabaeidae: Scarabaeinae) in an Amazonian area

AbstractAmong dung beetles, ‘sit and wait’ comprise a common strategy, in which individuals perch on leaves. The goal of this study was to assess the spatial dynamics of dung beetle perching in a region of the Amazon. We analysed the intra‐ and interspecific relationships between individual body size, leaf area, leaf shape, and the height at which beetles perched. When analysing intraspecifically, the larger individuals of Canthidium bicolor perched higher than the small ones. When considering the three most abundant species, the smallest species (C. bicolor) perches lower, the intermediate species (Canthidium deyrollei) perches higher, and the largest species (Canthon triangularis) perches at an intermediate height. The leaf area also explained the vertical distribution, both when considering all individuals and intraspecific for C. bicolor, where there is a positive relationship between leaf area and perch height. Our results suggest that intra‐ and interspecific perching dynamics also depend on species life history, which could be further analysed under functional group approaches.

A "signal-off" anodic photoelectrochemical sensor based on ZnIn2S4/TiO2 heterojunction for dopamine detection

Dopamine (DA) is an important neurotransmitter. Abnormal levels of it in human body can increase the risk of many neurological diseases. Thus, developing a simple, sensitive detection method of DA is crucial. In this paper, we reported a "signal-off" anodic PEC sensor based on fluorine-doped tin oxide (FTO) glass modified ZnIn2S4/TiO2 heterojunction (ZnIn2S4/TiO2/FTO) for DA detection. The experimental results show that the ZnIn2S4/TiO2/FTO electrode prepared by two-step hydrothermal method has a good photocurrent response performance under visible light. After incubation with DA, the photocurrent response decreases significantly because DA can rapidly oxidizes to polydopamine (PDA) through the action of superoxide radical (·O2−) and hydroxyl radical (·OH) intermediate species, which are intermediates produced by the ZnIn2S4/TiO2/FTO electrode under visible light irradiation. The constructed PEC sensor has a good linear relationship in the concentration range from 0.5 to 1000.0 μM, and its detection limit is 0.253 μM. In addition, the results of the proposed PEC sensor in real serum samples are satisfactory. The PEC sensor provides a promising platform for DA detection, laying the foundation for future advances in disease diagnosis and prevention.

Passive turbulent jet ignition of jet fuel in a rapid compression machine

Turbulent jet ignition is a promising alternative to conventional spark ignition systems to achieve rapid combustion of difficult-to-ignite mixtures. Jet ignition can facilitate combustion of lean mixtures at low pressure and temperature by ejecting hot reacting jets of unburned gases, intermediate species, and combustion products into the main chamber to accelerate overall ignition. These jets ignite the main chamber at multiple locations, reducing the time required for the main chamber charge to be consumed. The focus of this research is to gain an improved fundamental understanding of the turbulent jet ignition process of F-24 and air at low pressure and temperature conditions with lean (φ = 0.5) and stoichiometric (φ = 1.0) mixtures using 3D RANS simulations. A Rapid Compression Machine with pressure transducers in the pre-chamber and main chamber was modeled, and distinct events during the jet ignition process were determined from pressure measurements and their time derivatives of a single compression stroke. By understanding events during the jet ignition process with jet fuel, these results give insight into achieving stable combustion of heavy fuels at low pressure and temperature conditions with high levels of dilution.

Unraveling the Structure and Dynamics of Ac-PHF6-NH2 Tau Segment Oligomers.

The aggregation of the proteins tau and amyloid-β is a salient feature of Alzheimer's disease, the most common form of neurodegenerative disorders. Upon aggregation, proteins transition from their soluble, monomeric, and functional state into insoluble, fibrillar deposits through a complex process involving a variety of intermediate species of different morphologies, including monomers, toxic oligomers, and insoluble fibrils. To control and direct peptide aggregation, a complete characterization of all species present and an understanding of the molecular processes along the aggregation pathway are essential. However, this is extremely challenging due to the transient nature of oligomers and the complexity of the reaction networks. Therefore, we have employed a combined approach that allows us to probe the structure and kinetics of oligomeric species, following them over time as they form fibrillar structures. Targeting the tau protein peptide segment Ac-PHF6-NH2, which is crucial for the aggregation of the full protein, soft nano-electrospray ionization combined with ion mobility mass spectrometry has been employed to study the kinetics of heparin-induced intact oligomer formation. The oligomers are identified and characterized using high-resolution ion mobility mass spectrometry, demonstrating that the addition of heparin does not alter the structure of the oligomeric species. The kinetics of fibril formation is monitored through a Thioflavin T fluorescence assay. Global fitting of the kinetic data indicates that secondary nucleation plays a key role in the aggregation of the Ac-PHF6-NH2 tau segment, while the primary nucleation rate is greatly accelerated by heparin.

Experimental and numerical study of laminar burning velocity for Diisobutylene+ PRF/TRF mixtures

DIB (Diisobutylene, JC8H16) strongly correlates with real gasoline and significantly impacts the combustion behavior of alternative fuels designed as gasoline substitutes. However, accuracy concerns persist in laminar burning velocity data reported in literature. In this paper, the laminar burning velocities of DIB + air, DIB + PRF + air, and DIB + TRF + air mixtures were measured by the heat flux method at 1 atm. (PRF, Primary Reference Fuel; TRF, Toluene Reference Fuel) The equivalence ratio was controlled within 0.6–1.3, and the initial temperatures were set at 298K, 318K, and 338K. Additionally, by employing the mechanism proposed by Ren et al., the simulated values align with the experimental data, thus prompting the conduction of a reaction kinetic analysis. The analysis of chemical reaction kinetics reveals the reaction pathways of DIB, with a notable observation that an increase in temperature or a decrease in equivalence ratio can both lead to an elevation in the degree of unsaturation in the bonds of intermediate species. During laminar flame combustion, PRF and TRF compete with DIB for oxygen, with PRF appearing to have a stronger ability to capture oxygen. In addition, the laminar burning velocity temperature dependence coefficient α decreases first and then increases with the increase of the equivalence ratio, where the minimum α is obtained at equivalence ratio = 1.1. Additionally, the laminar burning velocity at higher initial temperatures is estimated by the extrapolation method and compared with the experimental data reported in literature.

Multicomponent Interface and Electronic Structure Engineering in Ir-Doped CoMO4-Co(OH)2 (M = W and Mo) Enable Promoted Oxygen Evolution Reaction.

The core principles of multicomponent interface and electronic structure engineering are essential in designing high-performance catalysts for the oxygen evolution reaction (OER). However, combining these aspects within a catalyst is a significant challenge. In this investigation, a novel approach involving the development of hybrid Ir-doped CoMO4-Co(OH)2 (M = W and Mo) hollow nanoboxes was introduced, enabling remarkably efficient water oxidation electrocatalysis. Constructed from ultrathin nanosheet-assembled hollow nanoboxes, these structures boast a wealth of active centers for intermediate species, which in turn enhance both charge transfer and mass transport capabilities. Moreover, the compelling electronic and synergistic effects arising from the interaction between CoMO4 and Co(OH)2 significantly bolster OER electrocatalysis by facilitating efficient electron transfer. The introduction of Ir atoms serves to strategically adjust the electronic structure, fine-tune its electronic state, and operate as active centers to enhance OER electrocatalysis, thus diminishing the overpotential. This configuration results in Ir-CoWO4-Co(OH)2 and Ir-CoMoO4-Co(OH)2 exhibiting impressively low overpotentials of 252 and 261 mV, respectively, to 10 mA cm-2. Utilized in conjunction with the Pt/C catalyst in a two-electrode system for overall water splitting, a mere 1.53 V cell potential is needed to achieve the desired 10 mA cm-2 current density.

Sunlight-promoted CO2 electroreduction with staggered p-n heterojunction by indium-doped bismuth 3D nanoflower structure on oxidized copper foam as self-standing photoelectric cathode over a wide potential window

Exploiting suitable photocathodes to achieve high photocurrent and long-term endurance is still a great challenge in photoelectrocatalytic CO2 reduction (PEC CO2) reactions. Herein, an In-doped Bi2O3 decorated oxidized copper foam (CBIO/CF) self-standing photoelectric cathode is well designed by the self-assembly process without an externally added binder. Via sunlight-promoted strategy, CBIO/CF with a unique 3D hierarchical nanoflower structure displays a superior faradaic efficiency of 90.0 % towards HCOOH over a wide potential window from −0.87 ∼ −1.17 VRHE and reaches 97.8 % at −0.87 VRHE with a partial current density of 14.41 mA cm−2. The in-situ Fourier transform infrared spectroscopy (FTIR) analysis demonstrates the abundant oxygen defects induced by In doping boost CBIO/CF absorbing substantive intermediate species related with formate generations, and porous structure accelerating mass transportation. Moreover, the well-designed staggered p-n heterojunctions of Cu2O and In-doped Bi2O3 on the surface of catalysts favor the generation and separation of electron/hole pairs and contribute to the photocatalytic reduction of CO2 under a bias voltage. This work paves the way for rational regulation of self-supporting photoelectrode for PEC CO2 to HCOOH with suitable conduction band valence bands and high performance and stability.

Enhanced water and urea electrolysis at industrial scale current density using self-supported VxNi1-xO trifunctional catalysts

An advance of highly efficient nanostructured electrocatalysts based on non-noble metals for water electrolysis and urea oxidation reaction (UOR) are of great significance for urea-enriched wastewater remediation and producing hydrogen. Herein, we report VxNi1-xO catalysts supported on three-dimensional Ni-foam scaffold for catalytic water and urea electrolysis. VxNi1-xO catalysts show rapid water and urea electrolysis due to enhanced electrochemical surface area (ECSA). Most important of all, the urea oxidation reaction has a lower potential of 1.418V vs RHE as compared to oxygen evolution reaction (1.684 V vs RHE) system to generate 100 mA/cm2. Additionally, a two-electrode cell for bi-functional water electrolysis generates 100 mA/cm2 at a potential of 2.10 V at 20 °C and just 1.86 V at 60 °C temperature due to regulated the adsorption/desorption of intermediates species, enhanced charge and mass transport, and easier desorption of oxygen molecules from the anode. The stability of VxNi1-xO catalyst was measured at 1000 mA/cm2 current density for up to 17 h.