Snowflake-like Cu2S as visible-light-carrier for boosting Pd electrocatalytic ethylene glycol oxidation under visible light irradiation

LED illumination-assisted activation of peroxydisulfate by heterogeneous Cu2S under alkaline condition for efficient organic pollutants removal

The copper-based materials were considered as promising catalysts for the activation of peroxydisulfate (PDS), but the study on the Cu2S-activated PDS under LED illumination and alkaline condition was little reported. In this work, Cu2S, a simple and readily available heterogeneous catalyst, was employed to enhance the activation of PDS under alkaline condition through LED illumination. The results indicated that under LED illumination, the degradation rate of tetracycline (TC) during the first 15 min was 3.55 times higher than that of the darkness. A series of important influencing factors were optimized, including anions, humic acid and complex water matrices. The results showed that the Cu2S/PDS/LED system exhibited excellent adaptability. Besides, the Cu2S maintained a good stability. The quenching experiments and electron spin resonance analysis demonstrated that the electron transfer and singlet oxygen were two primary pathways for the degradation of TC, and also other species such as sulfate and hydroxyl radicals played important roles. Furthermore, X-ray photoelectron spectroscopy characterization and a series of experiments confirmed that the Cu+ was the primary catalytic active sites, while the reductive sulfur species could directly activate PDS and accelerate the circulation of Cu2+/Cu+. The toxicity test proved that the toxicity of TC was decreased after the degradation. This study not only highlighted the potential of the Cu2S/PDS/LED system for efficient TC degradation under alkaline condition but also provided new insight for the development of Cu-based catalytic technology.

Combining Bismuth Telluride and Palladium for High Efficiency Glycerol Electrooxidation

Designing high-performance anodic catalysts to drive glycerol oxidation reaction (GOR) is essential for advancing direct alcohol fuel cells. Coupling Pd with oxophilic materials is an effective strategy to enhance its intrinsic catalytic activity. In this study, we successfully synthesized Pd/Bi2Te3 catalysts with tunable compositions, using Bi2Te3 as a novel promoter, and applied them to the GOR for the first time. Electrocatalytic tests revealed that the activity of the Pd/Bi2Te3 catalysts was closely linked to their compositions. Among these catalysts, the optimized Pd/Bi2Te3-20 % showed potential to replace the commercial Pd/C catalyst, exhibiting a peak current density 5.2 times higher than that of the benchmark Pd/C catalyst. Furthermore, improved catalytic stability and faster catalytic kinetics were observed for Pd/Bi2Te3-20 %. The synergistic effect between Pd and Bi2Te3 is responsible for the high performance of the Pd/Bi2Te3-20 % catalyst.

Tandem effect at snowflake-like cuprous sulphide interfaces for highly selective conversion of carbon dioxide to formate by electrochemical reduction

Electrochemical carbon dioxide reduction (ECR) is a commercially promising technology to resolve the energy dilemma and accomplish carbon recycling. Herein, a novel electrocatalyst has been investigated to produce formate (HCOOH) highly selectively during ECR by loading SnO2@C onto cuprous sulphide (Cu2S) to form a triplet effect at the interface. Snowflake-like Cu2S significantly enhances the local concentration of carbon dioxide (CO2) and promotes the binding of CO2 with SnO2, and the addition of carbon spheres enhances the electron transport, which is beneficial to the conversion of CO2 to HCOOH products. The snowflake-like Cu2S loaded with 1 wt% SnO2@C had an HCOOH Faraday Efficiency of 88% at -1.0 V (vs. Reversible Hydrogen Electrode, RHE), and the current density for CO2 reduction was stabilized at 15.6 mA cm-2, which was much higher than the HCOOH Faraday efficiency (FE) of 31.0% for pure Cu2S accompanied by a CO2 reduction current density of 3.9 mA cm-2. Combined investigations using in-situ Fourier transform infrared spectroscopy (FT-IR) with in-situ Raman spectra reveal that the active species is Cu+. Cu2S/1%SnO2@C can effectively promote the adsorption and activation of carbonate and inhibit the production of CO intermediates. The corresponding density functional theory (DFT) demonstrates that Cu2S/1%SnO2@C can well stabilize the HCOO* intermediate during the ECR process. The interaction between Cu2S and SnO2@C adjusts the surface electronic distribution and accelerates electron transfer, which efficiently improves CO2-to-HCOOH conversion. The result obtained from this work provides a simple and efficient electrocatalyst to enhance the HCOOH selectivity of ECR.

Pt nanoclusters embedded Fe-based metal-organic framework as a dual-functional electrocatalyst for hydrogen evolution and alcohols oxidation

Design and construction of high-efficiency and durable dual-functional electrocatalyst for clean energy electrocatalytic reaction is urgently desirable for mitigating the energy shortage and environmental deterioration issues. Herein, we prepared Pt nanoclusters with exposed (111) face plane embedded Fe-based metal-organic frameworks (Fe-MOF, MIL-100(Fe)) catalyst for electrocatalytic hydrogen evolution reaction (HER) and ethylene glycol oxidation reaction (EGOR). It is noted that the available oxygen sites on the surface of MIL-100(Fe) would form Pt-O interaction with Pt nanoclusters to acquire strong interfacial interaction, which endows Pt/MIL-100(Fe) electrocatalyst effective electron transfer, increasing catalytic active sites, accelerating proton-electron coupling, and improving conductivity. Benefitting from the desirable metal-supports interaction and derive merits for catalysis, the high electrocatalytic activity and durability for HER and EGOR were achieved as expected. Impressively, superior HER performance with higher current density, lower overpotential (46/29 mV in acidic/alkaline electrolyte) and smaller Tafel slope (19.7/37.8 mV dec^-1 in acidic/alkaline electrolyte) were acquired compared to commercial Pt/C. Moreover, Pt/MIL-100(Fe) electrode exhibits a rather high mass activity of 11826 mA mg^-1_Pt and long-term stability for EGOR. The present investigation demonstrates the promise of active metal/MOF combination for the interfacial strategy and rational design of dual-functional electrocatalyst, which has potential applications for future electrocatalysis field.

A Label-Free Electrochemical Immunosensor for CEA Detection on a Novel Signal Amplification Platform of Cu2S/Pd/CuO Nanocomposites

Carcinoembryonic antigen (CEA) is regarded as one of the crucial tumor markers for colorectal cancer. In this study, we developed the snowflake Cu₂S/Pd/CuO nanocomposite to construct an original label-free electrochemical immunosensor for the ultrasensitive detection of CEA levels. The nanocomposite of cuprous sulfide (Cu₂S) with Pd nanoparticles (Pd NPs) was synthesized through an in situ formation of Pd NPs on the Cu₂S. Cuprous sulfide (Cu₂S) and CuO can not only be used as a carrier to increase the reaction area but also catalyze the substrate to generate current signal. Palladium nanoparticles (Pd NPs) have excellent catalytic properties and good biocompatibility, as well as the ability of excellent electron transfer. The immunosensor was designed using 5 mmol/L H₂O₂ as the active substrate by optimizing the conditions with a detection range from 100 fg/ml to 100 ng/ml and a minimum detection limit of 33.11 fg/ml. The human serum was detected by electrochemical immunoassay, and the results were consistent with those of the commercial electrochemical immunosensor. Therefore, the electrochemical immunosensor can be used for the detection of human serum samples and have potential value for clinical application.

Ethylene Glycol Electrochemical Reforming Using Ruthenium Nanoparticle-Decorated Nickel Phosphide Ultrathin Nanosheets

In this work, ruthenium nanoparticle-decorated ultrathin nickel phosphide nanosheets on nickel foam substrate (Ru/Ni₂P/NF) nanocomposites are synthesized conveniently by a cyanogel-NaBH₄ method and a subsequent phosphating process, which displays excellent electroactivity for both the hydrogen evolution reaction (HER) and ethylene glycol electro-oxidation reaction (EGEOR) in an alkaline solution. Concretely, at Ru/Ni₂P/NF nanocomposites, only 1.37 and -0.13 V potentials are required to obtain a current density of 100 mA cm^-2 for EGEOR and HER, respectively. Meanwhile, Ru/Ni₂P/NF nanocomposites also exhibit pre-eminent electrocatalytic performance of the long-running process for both EGEOR and HER. Density functional theory calculations demonstrate that the introduction of Ru nanoparticles results in an optimization of the surface adsorption energy and construction of a synergistic catalysis interface, which improve the electrocatalytic performance of nickel phosphide nanosheets. Notably, a symmetric Ru/Ni₂P/NF||Ru/Ni₂P/NF ethylene glycol electrolyzer needs only 1.14 V electrolysis voltage to obtain 10 mA cm^-2 for hydrogen production, which effectively eliminates the H₂/O₂ explosion risk and highlights an energy-saving mode for electrochemical hydrogen production.

Photocatalytic Activity of Cu2S/WO3 and Cu2S/SnO2 Heterostructures for Indoor Air Treatment

Volatile organic compounds (VOCs) are commonly found in indoor spaces (e.g., homes or offices) and are often related to various illnesses, some of them with carcinogenic potential. The origins of VOC release in the indoor environment are in office products, building materials, electronics, cleaning products, furniture, and maintenance products. VOC removal can be done based on two types of technologies: adsorption in specific materials and decomposition via oxidative processes. The present article reports the development and photocatalytic activity of two heterostructures (Cu2S/WO3 and Cu2S/SnO2) used for indoor air decontamination. The acetaldehyde removal rate is discussed in correlation with the S-scheme mechanisms established between the heterostructure components but also comparatively with the bare catalysts' activity. Acetaldehyde was considered as a VOC reference because it was found by the International Agency for Research on Cancer to be one of the most frequent air toxins with potential carcinogenic effects. The samples contained monoclinic WO3, tetragonal SnO2, and orthorhombic Cu2S crystalline structures. The Cu2S crystallite size in the heterostructure varied from 75.9 to 82.4 Å, depending on the metal oxide substrate. The highest photocatalytic efficiency (75.7%) corresponded to Cu2S/SnO2, with a constant rate of 0.106 s-1 (which was three times faster than WO3 or SnO2 and seven and a half times faster than Cu2S).

Synergistic influence of mesoporous spinel nickel ferrite on the electrocatalytic activity of nano-structured palladium

Structure and surface area are critical factors for catalysts in fuel cells. Hence, a spinel nickel ferrite mesoporous (SNFM) is prepared via the solution combustion technique, an efficient and one-step synthesis. Dynamic X-ray analysis has clarified the structural properties of SNFM. The grain size of SNFM is determined to be ∼11.6 nm. The specific surface area (87.69 m2. g-1) of SNFM is obtained via the Brunauer-Emmett-Teller method. The Barrett-Joyner-Halenda pore size distributions revealed that the size of the mesopores in as-synthesized SNFM mainly falls in the size range of 2-16 nm. Scanning electron microscopy studies showed the regularities involved during porous-structure formation. SNFM is employed as the support for nano-structured palladium (PdNS). Field emission scanning electron microscope studies of PdNS-SNFM showed the deposition of PdNS in cavities and on/in the pores of SNFM. The electrochemical surface area obtained for PdNS-SNFM is about 27 times larger than that of PdNS via cyclic voltammetry. The electrochemical studies are utilized to study the features and catalytic performance of PdNS-SNFM in the electro-oxidation of diverse small organic fuels, whereas the electrooxidation of diethylene glycol is reported for first-time.