Highly efficient blackberry-like trimetallic PdAuCu nanoparticles with optimized Pd content for ethanol electrooxidation

Combining surface chemical functionalization with introducing reactive oxygen species boosts ethanol electrooxidation

The introduction of functional groups or oxygen vacancies into Pd-based electrocatalysts is a powerful strategy for enhancing the electrocatalytic performances for many electrocatalytic reactions. Herein, an amorphous ceria-modified Pd nanocomposite anchored on D-4-amino-phenylalanine (DAP)-functionalized graphene nanosheets (Pd-CeO_2-x/FGS) was prepared by a facile and effective one-pot synthetic strategy and further used as an electrocatalyst for the ethanol oxidation reaction (EOR) in alkaline electrolytes. The obtained Pd-CeO_2-x/FGS exhibits relatively high electrocatalytic activity, fast kinetics and excellent antipoisoning ability as well as robust durability for EOR, outperforming the comparable electrocatalysts as well as commercial Pd/C. The experimental results show that the enhanced EOR properties of Pd-CeO_2-x/FGS can be attributed to the DAP-functionalization and CeO_2-x-modification. Adequate functional groups (amino and carboxyl groups) and abundant oxygen vacancies were introduced in Pd-CeO_2-x/FGS by DAP-functionalization and CeO_2-x-modification. The functional groups facilitate the anchoring of small nanoparticles onto the substrate as well as modulate the electron density of Pd. The oxygen vacancies boost the adsorption ability of the reactive oxygen species (OH_ads) and accelerate the kinetics of the potential-limiting step for EOR. This study proposes a new strategy for the rational design of highly efficient catalysts for the electro-oxidation reaction.

Electroreduction of Nitrate to Ammonia on Palladium-Cobalt-Oxygen Nanowire Arrays

Developing high-efficiency electrocatalysts for the selective reduction of nitrate to valuable ammonia is of great significance. Herein, Pd-PdO-modified Co₃O₄ nanowire arrays on nickel foam (PdCoO/NF) are fabricated by a facile cation-exchange reaction. Pd and PdO can facilitate the generation of adsorbed hydrogen, and abundant oxygen vacancies can promote nitrate activation. Therefore, the PdCoO/NF exhibits a superior nitrate conversion rate (89.3%), Faradaic efficiency (88.6%), and ammonium selectivity (95.3%) at -1.3 V versus a saturated calomel electrode. The source of the produced ammonia is confirmed by ¹⁵N isotope labeling experiments and ¹H magnetic resonance. This presented synthetic method provides a powerful strategy for the preparation of nanowire arrays with controllable compositions for selective nitrate electroreduction to ammonia.

Evolution of PtCu tripod nanocrystals to dendritic triangular nanocrystals and study of the electrochemical performance to alcohol electrooxidation

In the field of catalysis, the design and construction of nanomaterials is an efficient way to optimize the catalytic activity of catalysts. This study presents the synthesis of PtCu tripod nanocrystals with branching structures and high purity prepared using a simple hydrothermal method. The dendritic PtCu triangular nanocrystals were successfully synthesized by regulating the amount of I^- ions to achieve different degrees of branching on PtCu nanocrystals, and the process was systematically studied and analyzed. Meanwhile, dumbbell nanocrystals of PtCu were successfully synthesized through slight adjustments to synthesis conditions. In electrochemical tests, the obtained dendritic PtCu triangular nanocrystals exhibited prominent electrocatalytic activity and long-term stability for ethylene glycol, methanol, and ethanol oxidation reactions due to the unique nanostructures as well as alloyed virtue, and were much better than commercial Pt/C. In addition, this study provides a general strategy for designing novel branched Pt-based nanomaterials with high electrocatalytic performance.

New Ultrasensitive Sandwich-Type Immunoassay of Dendritic Tri-Fan Blade-like PdAuCu Nanoparticles/Amine-Functionalized Graphene Oxide for Label-Free Detection of Carcinoembryonic Antigen

The early detection of tumor markers has an effective role in the treatment of cancer. Here, a new sandwich-type electrochemical immunosensor for early label-free detection of the cancer biomarker carcinoembryonic antigen (CEA) was developed. Dendritic tri-fan blade-like PdAuCu nanoparticles (PdAuCu NPs)/amine functionalized graphene oxide (NH₂-GO) were the label of secondary antibodies (Ab₂), and Au nanoparticle-decorated polydopamines (Au/PDA) were immobilized on a screen-printed carbon electrode (SPCE) as the substrate materials. Dendritic tri-fan blade-like PdAuCu NPs/NH₂-GO was synthesized according to a simple hydrothermal procedure and used to immobilize antibodies (Ab₂) with large surfaces areas, increased catalytic properties and good adsorption to amplify the current signals. Subsequently, Ab₂/PdAuCu NPs/NH₂-GO catalyzed the reduction of H₂O₂ in the sandwich-type immunoreactions. Under optimal conditions, the immunosensor exhibited a satisfactory response to CEA with a limit detection of 0.07 pg mL⁻¹ and a linear detection range from 0.1 pg mL⁻¹ to 200 ng mL⁻¹. The proposed immunosensor could be suitable enough for a real sample analysis of CEA, and has clinical value in the early diagnosis of cancer.