Ai-Jun Wang

Controlled fabrication of well-dispersed AgPd nanoclusters supported on reduced graphene oxide with highly enhanced catalytic properties towards 4-nitrophenol reduction

To realize the efficient and complete removal of organic pollutants in waste water, it is highly urgent for scalable synthesis of either self-supported bimetallic nanocatalysts or anchored on carbon-based materials. In this study, a simple one-pot coreduction method was developed for preparing well-dispersed AgPd alloyed nanoclusters uniformly dispersed on reduced graphene oxide (AgPd NCs/rGO) at room temperature by utilizing 5-azacytosine as the capping agent. The nanocomposites were characterized by a set of physical characterizations. The formation mechanism and catalytic mechanism were discussed in some details. Moreover, the prepared AgPd NCs/rGO exhibited dramatically increased catalytic properties towards the reduction of 4-nitrophenol (4-NP) in the presence of NaBH4 when compared to commercial Pd/C (20 wt.%).

One-pot aqueous fabrication of reduced graphene oxide supported porous PtAg alloy nanoflowers to greatly boost catalytic performances for oxygen reduction and hydrogen evolution

Herein, reduced graphene oxide supported porous PtAg alloy nanoflowers (PtAg NFs/rGO) were synthesized by a simple one-pot aqueous method using pyridinium-based dicationic ionic liquid (1,4-bis(pyridinium)butane dibromide, Bpb-2Br) as the new structure-director and stabilizing agent. The products were characterized by a series of techniques. The obtained nanocomposite had more positive onset potential (1.03 V) for oxygen reduction reaction (ORR) in alkaline electrolyte than those of commercial Pt/C (50 wt%, 0.96 V) and home-made Pt nanoparticles (NPs)/rGO (Pt NPs/rGO, 0.97 V), showing the enhanced catalytic performance for hydrogen evolution reaction (HER) with the positive onset potential (-26 mV) and a small Tafel slope (31 mV dec-1) relative to Pt/C (-18 mV, 31 mV dec-1) and Pt NPs/rGO (-42 mV, 36 mV dec-1) in 0.5 M H2SO4.

Dentritic platinum-palladium/palladium core-shell nanocrystals/reduced graphene oxide: One-pot synthesis and excellent electrocatalytic performances

Herein, we developed a facile one-pot co-reduction method to fabricate highly dentritic platinum-palladium/palladium core-shell nanocrystals on reduced graphene oxide (PtPd@Pd NCs/rGO), where poly-l-lysine (PLL) worked as the eco-friendly structure director and stabilizer. The nanocomposite was mainly characterized by microscopic analysis, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), along with the discussion of the formation mechanism. The synthesized PtPd@Pd NCs/rGO have the enlarged electrochemically active surface area (ECSA) of 51.65 m2 g-1, showing 1.3 folds enhancement in the peak current density relative to commercial Pt/C (50 wt%) for glycerol oxidation reaction (GOR), coupled with the small Tafel slope of 28 mV dec-1 for hydrogen evolution reaction (HER).

One-pot synthesis of single-crystal Pt nanoplates uniformly deposited on reduced graphene oxide, and their high activity and stability on the electrocalalytic oxidation of methanol.

We demonstrate a one-pot thermoreduction approach towards the preparation of single-crystal Pt nanoplates, which were uniformly deposited on the reduced graphene oxide (RGO) using polyvinylpyrrolidone (PVP) as a stabilizer. The size of Pt nanoplates can be tuned from 6.8 to 10.1 nm by controlling Pt loading. The as-prepared Pt/PVP/RGO catalysts show high stability and activity towards the methanol oxidation reaction (MOR). Their MOR current can reach up to 401 mA mg(-1) Pt and MOR current can maintain 89.4% of its initial value after 10 000 potential cycles.

Facile solvothermal fabrication of Pt 47 Ni 53 nanopolyhedrons for greatly boosting electrocatalytic performances for oxygen reduction and hydrogen evolution

Pt-based bimetallic nanostructures with low content of Pt were considered as one of the attractive nanocatalysts for their high Pt utilization efficiency, remarkable catalytic characters and cost-effectiveness in facilitating the sluggish cathodic reactions in fuel cells. Herein, three-dimensional Pt47Ni53 nanopolyhedrons (NPHs) with abundant active sites were constructed by a facile one-pot solvothermal strategy, in which cytosine and cetyltrimethylammonium chloride (CTAC) worked as the co-structure directing agents. The Pt47Ni53 NPHs were mainly characterized by a series of techniques, showing the high catalytic activity and stability towards oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) in comparison to Pt13Ni87 nanocrystals (NCs), Pt63Ni37 NCs, commercial Pt black and/or Pt/C catalysts. Impressively, the mass activity of Pt47Ni53 NPHs was about 215.80 mA mgPt-1 for ORR, approximately 4-time increase relative to Pt black (49.60 mA mgPt-1). These results demonstrate the promising applications of the synthesized nanocatalysts in energy storage and transformation.