As a potential substitute technique for conventional nitrate production, electrocatalytic nitrogen oxidation reaction (NOR) is gaining more and more attention. But, the pathway of this reaction is ...still unknown owing to the lack of understanding on key reaction intermediates. Herein, electrochemical in situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) and isotope‐labeled online differential electrochemical mass spectrometry (DEMS) are employed to study the NOR mechanism over a Rh catalyst. Based on the detected asymmetric NO2− bending, NO3− vibration, N=O stretching, and N−N stretching as well as isotope‐labeled mass signals of N2O and NO, it can be deduced that the NOR undergoes an associative mechanism (distal approach) and the strong N≡N bond in N2 prefers to break concurrently with the hydroxyl addition in distal N.
The powerful electrochemical in situ attenuated total reflection surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) and online differential electrochemical mass spectrometry (DEMS) techniques are employed to detect reaction intermediates. Based on the detected intermediates, the associative mechanism with the addition of hydroxyl at distal N (distal mechanism) is deduced for nitrogen oxidation reaction (NOR).
Shape-controlled catalysis: High-quality Pt-Cu nanocubes with an average size of about 8 nm (see picture, scale bar=20 nm) were synthesized from a high-temperature organic solution system in the ...presence of various capping ligands. These cubic Pt-Cu nanocrystals terminated with {100} facets demonstrated a superior catalytic activity towards methanol oxidation compared to similar sized Pt-Cu and Pt nanospheres.
•The triple-layered heterostructure provides abundant active sites for urea electrooxidation.•The synergistic effect between MnCo2O4.5 and Ni(OH)2 promotes the electrooxidation of urea.•The ...as-prepared MnCo2O4.5@Ni(OH)2/NF exhibits much better stability and activity towards urea electrooxidation.
Urea oxidation reaction (UOR) is considered as a prospective technology for hydrogen generation and degradation of urea-rich wastewater concurrently. In theory, nickel-based catalysts exhibit superior activity in this regard. However, the intrinsically low conductivity and limited active sites on usual nickel-based catalysts impede their applications in UOR. Hence, a hierarchical triple-layered heterostructure, which consists of MnCo2O4.5 nanosheets seamlessly sandwiched between a bottom layer of Ni foam substrate and a top layer of Ni(OH)2 nanosheets, are directly synthesized via a successive hydrothermal-calcination-hydrothermal process (MnCo2O4.5@Ni(OH)2/NF). Taking advantages of the distinctive sandwich structure and the synergistic effect between MnCo2O4.5 and Ni(OH)2, the resulting MnCo2O4.5@Ni(OH)2/NF electrode presents superior electrocatalytic activity with a small onset potential of 0.19 V versus Ag/AgCl as well as a current density of 650 mA cm−2 in 5 M KOH and 0.33 M urea electrolyte. This work provides a promising platform for designing an effective hybrid material toward a wide range of electrochemical applications.
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•Electro-oxidation realizes high selective leaching of Li+ from spent NCM batteries.•The selective leaching rate of Li+ reach more than 99%.•The leached lithium can be converted into ...high-purity Li2CO3 in one step.•Delithiation materials can achieve efficient degradation of sulfamethoxazole.•The removal efficiency of sulfamethoxazole reached 100% within 30 min.
This study aimed to further expand the scope of use of spent lithium-ion batteries (LIBs) and improve their value. We proposed a dual-function electro-oxidation strategy that can realize the highly selective recovery of Li+ from spent NCM batteries and the in situ modification of delithiation materials. Under the optimum conditions, the selective recovery rate of Li+ exceeded 99%. After electro-oxidation, the electrolyte can be directly heated and concentrated to obtain Li2CO3. Moreover, the large number of oxygen vacancies and metal vacancies produced by electro-oxidation, as well as the changes in structure and morphology, enabled the delithiation material to exhibit excellent catalytic performance. Within 30 min, the degradation rate of sulfamethoxazole reached 100%. This strategy can be used to recycle and reuse spent LIBs and thus achieve the goal of “turning waste into treasure”.
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•·Mo2C-FeCu catalyst was designed by thermal reduction and carburization of precursor.•·cinnamaldehyde/benzalacetone were synthesized at high yields and ...selectivities.•·α,β-unsaturated aldehyde/ketone were electrosynthesized in gentle and green manner.•·CC coulping reaction was fulfilled by combined electrochemical-chemical pathway.
Oxygen evolution reaction (OER) is the efficiency limiting half-reaction in water electrolysis for green hydrogen production due to the 4-electron multistep process with sluggish kinetics. The electrooxidation of thermodynamically more favorable organics accompanied by CC coupling is a promising way to synthesize value-added chemicals instead of OER. Efficient catalyst is of paramount importance to fulfill such a goal. Herein, a molybdenum iron carbide-copper hybrid (Mo2C-FeCu) was designed as anodic catalyst, which demonstrated decent OER catalytic capability with low overpotential of 238 mV at response current density of 10 mA cm−2 and fine stability. More importantly, the Mo2C-FeCu enabled electrooxidation assisted aldol condensation of phenylcarbinol with α-H containing alcohol/ketone in weak alkali electrolyte to selective synthesize cinnamaldehyde/benzalacetone at reduced potential. The hydroxyl and superoxide intermediate radicals generated at high potential are deemed to be responsible for the electrooxidation of phenylcarbinol and aldol condensation reactions to afford cinnamaldehyde/benzalacetone. The current work showcases an electrochemical-chemical combined CC coupling reaction to prepare organic chemicals, we believe more widespread organics can be synthesized by tailored electrochemical reactions.
Carbon quantum dots (CQDs) synthesized from biological sources play a significant role in biomedical and environmental applications, including bioimaging, biosensing, metal ions detection and ...electrocatalytic oxidations. Herein, we synthesized blue-emitting carbon quantum dots using maple tree leaves via a one-step hydrothermal process to detect Cesium ions selectively. The synthesized CQDs' functional group composition, morphology, and pH stability was analytical and morphologically investigated. The maple leaves derived carbon quantum dots (M-CQDs) exhibited blue fluorescence, and their sizes ranged from 1 to 10 nm. They exhibited emission at 445 nm upon excitation at 360 nm. M-CQDs PL intensity was highly stable for about 100 d without any changes and confirmed that the as-prepared CQDs could be used as a probe for Cesium ion sensing. M-CQDs were effectively used as Cesium sensing probes based on the electron transfer process and simultaneously used as a catalyst for glycerol electrooxidation. The PL intensity of M-CQDs was quenched while adding the varies concentration of Cesium ions in the linear range from 100 μM to 100 nM with the detection limit of (LOD) 160 nM, simultaneously electrocatalytic oxidation of glycerol showed an onset potential of 1.32 V at a current density of 10 mA/cm2.
•One-pot hydrothermal synthesis of carbon quantum dots (M-CQDs) derived from maple leaves using a greener approach.•M-CQDs exhibit blue fluorescence and also displays PL stability of 100 days.•Morphological affirmation of M-CQDs via TEM and AFM visualizes around 1–10 nm.•PL quenching upon the interaction of cesium ions with M-CQDs holding a detection limit of 24 nM and 40 nM in the real sample.•Electrocatalytic oxidation of glycerol in alkaline medium displays significant behavior and long-term durability.
Electrocatalytic conversion of methane (CH4) into high-valued liquid products have been studied extensively, yet still limited by their low product yields. Herein, we report the electrocatalytic ...conversion of CH4 into CH3COOH in HCO3--contained electrolyte. By optimizing the surface-active sites via defects engineering, a high CH3COOH yield of 347.31 mmol gcat−1 h−1, accompanied with a CH3COOH selectivity of 85.4 %, was obtained at 1.3 V vs RHE over the optimal catalyst. This CH3COOH yield is 2–5 orders of magnitude to previous reports so far as we know. Combinations of DFT theoretical simulation, defect sites characterization and control experiments of CH4 electrochemical conversion confirmed the important roles of ample surface Zn/O defects. Our work provides a new insight into the design of highly active and selective catalysts toward CH4 electrocatalytic conversion into CH3COOH.
•ZnO nanosheets with plenty of atomic defects were synthesized.•They were used for highly efficient CH4 conversion to acetic acid.•High yield rate and selectivity of 3473115 μmol (gcat h)−1 and 85.4 % are achieved.•The electrocatalytic performance outperforms the previous reports as we know.•Roles of Zn/O atom defects were studied in detail.
A novel electrocatalytic system was developed to realize one-pot conversion of organic pollutants into liquid fuels such as methanol (CH3OH) and ethanol (C2H5OH). The process combines the catalytic ...oxidation of organic pollutants with electrocatalytic reduction of CO2. We first coupled the electrocatalytic process with SO4•−-based advanced oxidation processes (AOPs) for the degradation of 4-nitrophenol (4-NP) using a 3D-hexagonal Co3O4 anode. In this step, 4-NP was mineralized to CO2, and then the CO2 was converted to CH3OH and C2H5OH by electrocatalytic reduction using a flower-like CuO cathode. The experimental results show the destruction of 4-NP (60 mL, 10 mg/L) can be as high as 99%. In addition, the yields of CH3OH and C2H5OH were 98.29 μmol/L and 40.95 μmol/L, respectively, which represents a conversion of 41.8% of 4-NP into liquid fuels; the electron efficiency was 73.1%. In addition, we found that 3D-hexagonal arrays of Co3O4 with different morphologies can be obtained by adding different amounts of urea. We also investigated the formation mechanism of novel 3D-hexagonal Co3O4 arrays for the first time. A mechanism was proposed to explain the electrocatalytic steps involved in the conversion of 4-NP to CH3OH and C2H5OH and the synergetic effects between AOPs and electrocatalysis.
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•Organic pollutants to hydrocarbons was fulfilled in one electrocatalytic system.•SO4.•− for high-efficient degradation of organic pollutants was proposed.•3D-hexagonal Co3O4 array was prepared and formation mechanism was proposed.•A mechanism was proposed to explain the electrocatalytic steps.
The present study aims to evaluate the efficacy of the electro-oxidation (EO) process using graphite and stainless steel electrode for the primary treatment of leachate generated from the industrial ...waste landfill site. Response surface methodology (RSM) was used to optimise process variables, viz., initial pH, current density, and electrolysis time to obtain maximum COD removal. The optimum 30 mA/cm2 current density, initial pH 7 and 35 min electrolysis time with graphite cathode showed 89.53 % COD removal. While stainless steel cathode showed 75.30 % COD removal with 19.70 mA/cm2 current density, initial pH 5.5, and 174-min electrolysis time as suggested optimum conditions. The results indicated that the graphite cathode improved EO performance compared to stainless steel.
•For glycerol electrooxidation the anodic limit of Pd-electrodes is superior to their ECSA.•The adsorption of glycerol appears to be not a dominant factor in its total electrooxidation route.•Role of ...molecular oxygen in electrooxidation of glycerol on Pd-modified electrodes was revealed.•The larger Pd-particles better catalyze glycerol oxidation.
Herein, a study dealing with a progress on palladium (Pd) electrocatalysts for an efficient glycerol electrooxidation in model aqueous and real fermentation solutions with special focus on some physicochemical parameters (e.g., the impact of adsorption stage of multiple species, presence of oxygen, influence of anodic limits and Pd-size) was conducted. During the course of investigations by tandem of an optical oxygen minisensor and cyclic voltammetry a significant impact of oxygen on the efficiency of glycerol electrooxidation on Pd electrocatalysts at alkaline pH in model aqueous and yeast fermentation media was revealed.
The obtained knowledge was used for the optimization of an assay utilizing Pd-sensing layers for glycerol determination and quantification in yeast fermentation medium. Received results showed a satisfactory agreement with a control measurement carried out by gas chromatography mass-spectrometry.
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