Hairong Xue

One-step fabrication of tri-metallic PdCuAu nanothorn assemblies as an efficient catalyst for oxygen reduction reaction

The design of highly branched Pd-based nanostructures is very important for various electrocatalytic applications. Herein, we report a very simple one-step method for direct fabrication of tri-metallic PdCuAu nanothorn assemblies (PdCuAu NAs) in aqueous solution. The obtained unique PdCuAu NAs with a well-defined shape are highly branched and self-supported nanostructures assembled from staggered nanothorns as building blocks, and exhibit superior catalytic activity, durability and methanol-tolerant ability for the oxygen reduction reaction, benefiting from their branched structure and tri-metallic compositions. In comparison with traditional routes, the newly developed one-step fabrication method without the need for any seed, multi-step procedure and organic solvent is very feasible for the fabrication of branched multi-metallic Pd-based catalysts with designed compositions.

Low-ruthenium-content NiRu nanoalloys encapsulated in nitrogen-doped carbon as highly efficient and pH-universal electrocatalysts for the hydrogen evolution reaction

Rational design and synthesis of low-cost and robust electrocatalysts for the hydrogen evolution reaction (HER) is critical for the development of water electrolysis technology. In this work, low-ruthenium-content NiRu alloy nanoparticles encapsulated in nitrogen-doped carbon (NiRu@N–C) have been prepared through doping ruthenium species into nickel-based metal–organic frameworks followed by pyrolysis treatment. Benefiting from their unique structural advantages and synergic effect of the components, the as-obtained NiRu@N–C nanohybrids exhibited excellent electrocatalytic activity and good stability towards the HER in acidic, neutral, and alkaline solutions.

Direct fabrication of tri-metallic PtPdCu tripods with branched exteriors for the oxygen reduction reaction

Design of multi-metallic nanocrystals with branched structures is very important for catalytic applications. Herein, a one-step synthesis of unique tri-metallic PtPdCu tripods with branched exteriors (PtPdCu TPs) in an aqueous solution is presented. Benefiting from their spatially and locally separated branches and tri-metallic compositions, the PtPdCu TPs exhibit superior activity and durability for the oxygen reduction reaction. The newly designed PtPdCu TPs are quite different from previous tripods in their branched exteriors. The developed one-step method is very feasible for the preparation of Pt-based multi-metallic tripods with designed compositions and desired performances.

Direct synthesis of bimetallic PtCo mesoporous nanospheres as efficient bifunctional electrocatalysts for both oxygen reduction reaction and methanol oxidation reaction

The engineering of electrocatalysts with high performance for cathodic and/or anodic catalytic reactions is of great urgency for the development of direct methanol fuel cells. Pt-based bimetallic alloys have recently received considerable attention in the field of fuel cells because of their superior catalytic performance towards both fuel molecule electro-oxidation and oxygen reduction. In this work, bimetallic PtCo mesoporous nanospheres (PtCo MNs) with uniform size and morphology have been prepared by a one-step method with a high yield. The as-made PtCo MNs show superior catalytic activities for both oxygen reduction reaction and methanol oxidation reaction relative to Pt MNs and commercial Pt/C catalyst, attributed to their mesoporous structure and bimetallic composition.

Tri-metallic PtPdAu mesoporous nanoelectrocatalysts

The design of mesoporous materials with multi-metallic compositions is highly important for various electrocatalytic applications. In this paper, we demonstrate an efficient method to directly fabricate tri-metallic PtPdAu mesoporous nanoparticles (PtPdAu MNs) in a high yield, which is simply performed by heating treatment of the reaction mixture aqueous solution at 40 °C for 4 h. Profiting from its mesoporous structure and multi-metallic components, the as-prepared PtPdAu MNs exhibit enhanced electrocatalytic activities toward both methanol oxidation reaction and oxygen reduction reaction in comparison with bi-metallic PtPd MNs and commercial Pt/C catalyst.

In situ coating of a continuous mesoporous bimetallic PtRu film on Ni foam: a nanoarchitectured self-standing all-metal mesoporous electrode

The fabrication of continuous mesoporous Pt-based alloy films is very important for electrochemical energy conversion. Herein, we propose an extremely simple soaking method for achieving in situ fabrication of a continuous mesoporous PtRu film on macroporous Ni foam (mPtRu–NF). Owing to its continuous mesoporous structure and bi-metallic compositions, the mPtRu–NF exhibits high activity and durability for both the oxygen reduction reaction and oxygen evolution reaction. Furthermore, when the mPtRu–NF was used as a binder-free air electrode for rechargeable Zn–air batteries (ZABs), it shows superior electrochemical performance. Being very different from previous complex de-alloying or template-based approaches, this method provides a truly simple way for achieving direct fabrication of mesoporous metallic films on metallic substrates. The proposed one-step method is readily available for scale-up fabrication of continuous mesoporous Pt-based films on metallic substrates with designed compositions and desired performances.

Constructing Ordered Three-Dimensional TiO2 Channels for Enhanced Visible-Light Photocatalytic Performance in CO2 Conversion Induced by Au Nanoparticles

As a typical photocatalyst for CO2 reduction, practical applications of TiO2 still suffer from low photocatalytic efficiency and limited visible-light absorption. Herein, a novel Au-nanoparticle (NP)-decorated ordered mesoporous TiO2 (OMT) composite (OMT-Au) was successfully fabricated, in which Au NPs were uniformly dispersed on the OMT. Due to the surface plasmon resonance (SPR) effect derived from the excited Au NPs, the TiO2 shows high photocatalytic performance for CO2 reduction under visible light. The ordered mesoporous TiO2 exhibits superior material and structure, with a high surface area that offers more catalytically active sites. More importantly, the three-dimensional transport channels ensure the smooth flow of gas molecules, highly efficient CO2 adsorption, and the fast and steady transmission of hot electrons excited from the Au NPs, which lead to a further improvement in the photocatalytic performance. These results highlight the possibility of improving the photocatalysis for CO2 reduction under visible light by constructing OMT-based Au-SPR-induced photocatalysts.

Ambient Electrochemical Synthesis of Ammonia from Nitrogen and Water Catalyzed by Flower-Like Gold Microstructures

Electrochemical nitrogen reduction to ammonia is proposed as a promising alternative to the Haber-Bosch process because it can be driven by renewable electricity at ambient conditions. Currently, the development of such a process is hampered by the lack of efficient electrocatalysts for the nitrogen reduction reaction (NRR). Herein, we report a super-rapid approach for the synthesis of flower-like Au microstructures (Au flowers) within 5u2005s. The obtained Au structures are assembled by staggered nanoplates as building blocks, which provide abundant electrocatalytically active sites for the NRR. The Au flowers achieve a high performance (NH3 yield: 25.57u2005μgu2009h-1 u2009mgcat. -1 ; faradaic efficiency: 6.05u2009%), 100u2009% selectivity (no N2 H4 production), and long-term durability toward the electrochemical ammonia production. The work is highly valuable for the rapid synthesis of active catalysts for the NRR.

Enhanced Dual Fuel Cell Electrocatalysis with Trimetallic PtPdCo Mesoporous Nanoparticles

The facile preparation of platinum-based catalysts with designed compositions and structures is of great importance for fuel cells. In this work, a one-pot method is developed to synthesize monodispersed trimetallic PtPdCo mesoporous nanoparticles (PtPdCo MNs) with uniform morphology and size. The proposed synthetic method does not require any hard template or organic solvent, which greatly simplifies the preparation procedure. PtPdCo MNs, with a highly porous structure, exhibit enhanced electrocatalytic activities and excellent stabilities for both the formic acid oxidation reaction and the oxygen reduction reaction, relative to bimetallic PtPd MNs and commercial Pt/C catalyst. The proposed synthetic method is highly valuable for the design of mesoporous multimetallic catalysts for fuel cells.

Ultrathin nitrogen-doped graphitized carbon shell encapsulating CoRu bimetallic nanoparticles for enhanced electrocatalytic hydrogen evolution

Design of highly active and cost-effective electrocatalysts is very important for the generation of hydrogen by electrochemical water-splitting. Herein, we report the fabrication of ultrathin nitrogen-doped graphitized carbon shell encapsulating CoRu bimetallic nanoparticles (CoRu@NCs) and demonstrate their promising feasibility for efficiently catalyzing the hydrogen evolution reaction (HER) over a wide pH range. The resultant CoRu@NC nanohybrids possess an alloy-carbon core-shell structure with encapsulated low-ruthenium-content CoRu bimetallic alloy nanoparticles (10-30 nm) as the core and ultrathin nitrogen-doped graphitized carbon layers (2-6 layers) as the shell. Remarkably, the optimized catalyst (CoRu@NC-2 sample) with a Ru content as low as 2.04 wt% shows superior catalytic activity and excellent durability for HER in acidic, neutral, and alkaline conditions. This work offers a new method for the design and synthesis of non-platium-based electrocatalysts for HER in all-pH.