Bio-directed one-pot synthesis of Pt-Pd alloyed nanoflowers supported on reduced graphene oxide with enhanced catalytic activity for ethylene glycol oxidation

Bionic Magnetic Sensor Based on the MagR/Cry4 Complex-Configured Graphene Transistor with an Integrated On-Chip Gate

Magnetic-sensitive proteins are regarded as key factors in animals' precise perception of the geomagnetic field. Accurate feedback on the response of these tiny proteins to magnetic fields remains a challenge. Here, we first propose a real-time accurate magnetic sensor based on the MagR/Cry4 complex-configured graphene transistor with an integrated on-chip gate. A nanometer-thick denatured bovine serum albumin film was used as the bio-interface of graphene electrolyte-gated transistors (EGTs) to immobilize the MagR/Cry4 complex. With the optimization and characterization of this bionic graphene EGT, it could detect magnetic fields in real time with a sensitivity of 1 mT, which is far lower than in earlier research. It was concluded that our MagR/Cry4 complex-configured graphene EGTs with a side-gate held great promise in terms of geomagnetic field detection. Furthermore, the constructed approach in this paper could also be utilized as a general solution for recording the response of magnetically sensitive biomolecules to magnetic fields in real time.

Effect of Pd on the Electrocatalytic Activity of Pt towards Oxidation of Ethanol in Alkaline Solutions

The understanding of electrocatalytic activity and poisoning resistance properties of Pt and Pd nanoparticles, recognized as the best electrocatalysts for the ethanol oxidation reaction, is an essential step for the commercialization of direct ethanol fuel cells (DEFCs). In this paper, mono and bimetallic Pt and Pd nanoparticles with different atomic ratios have been synthesized to study their electrocatalytic properties for an ethanol oxidation reaction in alkaline solutions. The different nanoparticles were physiochemically characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrochemical characterization was performed by cyclic voltammetry and chronoamperometry measurements. The electrochemical measurements indicate that Pt nanoparticles have much higher electrocatalytic activity for ethanol oxidation than Pd nanoparticles. The studies with bimetallic PtPd nanoparticles showed a significant impact of their composition on the ethanol oxidation. Thus, the highest electrocatalytic activity and poisoning resistance properties were obtained for Pt3Pd2 nanoparticles. Moreover, this study demonstrates that the poisoning of the catalyst surface through ethanol oxidation is related to the prevalence of the acetaldehyde–acetate route and the polymerization of acetaldehyde through aldol condensation in the alkaline media.

Polyol assisted formaldehyde reduction of bi-metallic Pt-Pd supported agro-waste derived carbon spheres as an efficient electrocatalyst for formic acid and ethylene glycol oxidation

This report explains, (i) the preparation of carbon spheres (CS) from agro-waste through hydrothermal carbonization (HTC) followed by high temperature carbonization, (ii) the decoration of bi-metallic Pt-Pd nanoparticles (Pt-Pd NPs) with different compositions (Pt/C, Pt_0.5Pd₁/C, Pt₁Pd₁/C and Pt₁Pd_0.5/C, Pd/C) on the carbon by ethylene glycol solvated polyol assisted formaldehyde reduction method and (iii) subsequently used as the electrocatalyst for formic acid (FA) and ethylene glycol (EG) electro-oxidation. The structural and morphological properties of the electrocatalysts were studied using advanced physicochemical characterization techniques. The obtained results well evidence the homogeneous dispersion of Pt-Pd NPs on the surface of the carbon. Especially, Pt_0.5Pd₁/C exhibited excellent electrocatalytic property towards formic acid electro-oxidation reaction (FAOR) with a higher current density (256 mA cm^-2) and stability due to "third body effect". On the other hand, Pt₁Pd_0.5/C expressed superior electrochemical performance towards ethylene glycol electro-oxidation reaction (EGOR) due to the strong interaction between high Pt content and Pd. Hence, this work reveals the improved electrocatalytic performance of bi-metallic Pt-Pd NPs supported biomass-derived carbon as a promising anodic electrocatalyst towards FAOR and EGOR.

Highly efficient ethylene glycol electrocatalytic oxidation based on bimetallic PtNi on 2D molybdenum disulfide/reduced graphene oxide nanosheets

In this paper, a two-dimensional (2D) hybrid material of molybdenum disulfide (MoS₂)/reduced graphene oxide (RGO) is facilely synthesized and used as an ideal support for the deposition of Pt nanoparticles. The as-prepared Pt/MoS₂/RGO composites are further worked as electrocatalysts towards ethylene glycol oxidation reaction (EGOR). In addition, when alloying with Ni, the composite shows obvious enhancement in electrocatalytic performance for EGOR. Specifically, the optimized molar ratio of Pt to Ni is 3:1, namely Pt₃Ni/MoS₂/RGO performs the strongest current density of 2062 mA mg^-1_Pt, which is 11.1, 5.80 and 2.40 times higher than those of Pt, Pt₃Ni and Pt/MoS₂/RGO electrodes, respectively. The systematically electrochemical measurements indicate that the largely promoted electrocatalytic performances of Pt₃Ni/MoS₂/RGO are mainly attributed to the synergistic effect of Ni and Pt, and 2D sheets of MoS₂/RGO. This excellent performance indicates that the reported electrocatalytic material could be an efficient catalyst for the application in direct ethylene glycol fuel cell and beyond.

Sophisticated Construction of Binary PdPb Alloy Nanocubes as Robust Electrocatalysts toward Ethylene Glycol and Glycerol Oxidation

The design of nanocatalysts by controlling pore size and particle characteristics is crucial to enhance the selectivity and activity of the catalysts. Thus, we have successfully demonstrated the synthesis of binary PdPb alloy nanocubes (PdPb NCs) by controlling pore size and particle characteristics. In addition, the as-obtained binary PdPb NCs exhibited superior electrocatalytic activity of 4.06 A mg^-1 and 16.8 mA cm^-2 toward ethylene glycol oxidation reaction and 2.22 A mg^-1 and 9.2 mA cm^-2 toward glycerol oxidation reaction when compared to the commercial Pd/C. These astonishing characteristics are attributed to the attractive nanocube structures as well as the large number of exposed active areas. Furthermore, the bifunctional effects originated from Pd and Pb interactions help to display high endurance with less activity decay after 500 cycles, showing a great potential in fuel cell applications.

One-pot synthesis of a PtPd dendritic nanocube cage superstructure on graphenes as advanced catalysts for oxygen reduction

How to use Pt economically and efficiently in the oxygen reduction reaction (ORR) is of theoretical and practical significance for the industrialization of the proton-exchange membrane fuel cells. In order to minimize Pt consumption and optimize the ORR performance, the ORR catalysts are recommended to be designed as a porous nanostructure. Herein, we report a one-pot solvothermal strategy to prepare PtPd dendritic nanocube cages via a galvanic replacement mechanism triggered by an I^- ion. These PtPd alloy crystals are nanoporous, and uniformly dispersed on reduced graphene oxides (RGOs). The size of the PtPd dendritic nanocube cages can be easily tuned from 20-80 nm by controlling their composition. Their composition is optimized to be 1:5 Pt/Pd atomic ratio for these RGO-supported PtPd dendritic nanocages. This catalyst shows superior ORR performance with a specific activity of 2.01 mA  cm^-2 and a mass activity of 4.45 A  mg^-1 Pt, far above those for Pt/C catalysts (0.288 mA  cm^-2 for specific activity, and 0.21 A  mg^-1 Pt for mass activity). In addition to ORR activity, it also exhibits robust durability with almost negligible decay in ORR mass activity after 10 000 voltammetric cycling.

Green synthesis of Pt–Pd bimetallic nanoparticle decorated reduced graphene oxide and its robust catalytic activity for efficient ethylene glycol electrooxidation

A simple one-pot green synthesis technique is developed to prepare the Pt–Pd bimetallic nanoparticles decorated reduced graphene oxide nanocomposite and its robust catalytic activity for efficient and durable ethylene glycol oxidation is realized.

Enhancement of interaction of L-929 cells with functionalized graphene via COOH+ ion implantation vs. chemical method

Low hydrophilicity of graphene is one of the major obstacles for biomaterials application. To create some hydrophilic groups on graphene is addressed this issue. Herein, COOH+ ion implantation modified graphene (COOH+/graphene) and COOH functionalized graphene were designed by physical ion implantation and chemical methods, respectively. The structure and surface properties of COOH+/graphene and COOH functionalized graphene were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and contact angle measurement. Compared with graphene, COOH+/graphene and COOH functionalized graphene revealed improvement of cytocompatibility, including in vitro cell viability and morphology. More importantly, COOH+/graphene exhibited better improvement effects than functionalized graphene. For instance, COOH+/graphene with 1 × 1018 ions/cm2 showed the best cell-viability, proliferation and stretching. This study demonstrated that ion implantation can better improve the cytocompatibility of the graphene.